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Journal Articles: River Deltas and Climate Change

Articles  :   Geology  |   Ecosystems  |   Climate Change  |   Sea Level Rise  |   Fauna  |   Birds  |   Fish

Amadi, A. A. (1990). "A Comparative Ecology of Estuaries in Nigeria." Hydrobiologia 208(1-2): 27-38.

A bar-built estuary, a drowned river valley and two river delta estuaries were compared and contrasted to elucidate the impact of some abiotic factors, notably climate, salinity, and oxygen on the distribution of the aquatic fauna and flora. Salinity was recognizable as the key factor responsible for the population dynamics in these habitats. The mangrove community is characteristically zoned, but development and distribution of the trees is restricted in view of coastal geomorphic and hydrological processes to the western banks of the estuaries. The preponderance of marine fish species in estuaries was confirmed, although the wide salinity tolerance of some prolific-breeding Cichlidae from freshwater was noted. Forty-eight species of bony fishes were recorded in Lagos Lagoon, the Escravos, and Qua Ibo estuaries and classified by salinity tolerance into stenohaline and euryhaline marine species (66%), and freshwater species (34%). The same estuarine ichthyofauna were split into trophic groups: piscivores (46%), zooplankton feeders (10%), meiobenthos feeders (27%), and macrobenthos feeders (17%).

Andreev, A., P. Tarasov, et al. (2004). "Holocene paleoenvironmental records from Nikolay Lake, Lena River Delta, Arctic Russia." Palaeogeography Palaeoclimatology Palaeoecology 209(1-4): 197-217.

Radiocarbon-dated pollen, rhizopod, chironomid and total organic carbon (TOC) records from Nikolay Lake (73degrees20'N, 124degrees 12' E) and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the Holocene in the Lena Delta area. Shrubby Alnus fruticosa and Betula exilis tundra existed during 10,300-4800 cal. yr BP and gradually disappeared after that time. Climate reconstructions based on the pollen and chironomid records suggest that the climate during ca. 10,300-9200 cal. yr BP was up to 2-3 degreesC warmer than the present day. Pollen-based reconstructions show that the climate was relatively warm during 9200-6000 cal. yr BP and rather unstable between ca. 5800-3700 cal. yr BP. Both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modem-day conditions after ca. 3600 cal. yr BP. The chironomid-based temperature reconstruction suggests a relatively warm period between ca. 2300 and 1400 cal. yr BP, which corresponds to the slightly warmer climate conditions reconstructed from the pollen. Modem chironomid and rhizopod assemblages were established after ca. 1400 cal. yr BP. (C) 2004 Elsevier B.V. All rights reserved.

Asch, F. and M. C. S. Wopereis (2001). "Responses of field-grown irrigated rice cultivars to varying levels of floodwater salinity in a semi-arid environment." Field Crops Research 70(2): 127-137.

Shallow saline water tables, naturally saline soils and variations in climatic conditions over the two growing seasons, create a harsh environment for irrigated rice production in the Senegal River Delta. At the onset of the growing season, salts accumulated by capillary rise in the topsoil are released into the soil solution and floodwater. Rice fields often lack drainage facilities, or drain from one field to the other, thus building up salt levels during the season. Salt stress may, therefore, occur throughout the growing season and may coincide with susceptible growth stages of the rice crop. The objectives of the present study were to (i) determine varietal responses to seasonal salinity in both the hot dry season (HDS) and the wet season (WS) and (ii) derive guidelines for surface water drainage at critical growth stages. We evaluated responses of three rice cultivars grown in the region to floodwater salinity (0-2, 3, 6, 8 mS cm(-1)), applied either at germination, during 2 weeks at crop establishment, during 2 weeks around panicle initiation (PI), or during 2 weeks around flowering. Floodwater electrical conductivity (EC) reduced germination rate for the most susceptible cultivar by as much as 50% and yield by 80% for the highest salinity level imposed. Salinity strongly reduced spikelet number per panicle, 1000 grain weight and increased sterility, regardless of season and development stage. The strongest salinity effects on yield were observed around PI, whereas plants recovered best from stress at seedling stage. Floodwater EC <2 mS cm(-1) hardly affected rice yield. For floodwater EC levels >2 mS cm(-1), a yield loss of up to 1 t ha(-1) per unit EC (mS cm(-1)) was observed for salinity stress around PI (at fresh water yields of about 8 t ha(-1). Use of a salinity tolerant cultivar reduced maximum yield losses to about 0.6 t ha(-1) per unit EC. It is concluded that use of salinity tolerant cultivars, drainage if floodwater EC >2 mS cm(-1) at critical growth stages, and early sowing in the WS to avoid periods of low air humidity during the crop cycle, are ways to increase rice productivity in the Senegal River Delta. (C) 2001 Elsevier Science B.V. All rights reserved.

Asuma, Y., S. Iwata, et al. (1998). "Precipitation features observed by Doppler radar at Tuktoyaktuk, Northwest Territories, Canada, during the Beaufort and Arctic storms experiment." Monthly Weather Review 126(9): 2384-2405.

In the fall of 1994, the Beaufort and Arctic Storms Experiment (BASE) was held to collect information on the structure and evolution of mesoscale weather systems over the southern Beaufort Sea and the Mackenzie River delta of the western Canadian Arctic. As part of the experiment, X-band Doppler radar observations were carried out at Tuktoyaktuk, a village on the shore of the Beaufort Sea. In this paper, the precipitation features, structure, and moisture transport associated with two distinctly different weather systems that were observed during BASE are described with a variety of datasets. Climatologies of storm activity in the area suggest these two types of different weather systems, the so-called Pacific origin and storm track disturbances, are the most frequently observed in this region during the fall months. The characteristic feature of a Pacific origin weather system is a pronounced layering of the air masses. In the upper layer, the air mass is of Pacific origin and is associated with a deep low in the Gulf of Alaska. As a result it is moist and is capable of producing precipitation. In contrast, the lower Layer is initially of continental origin and is associated with a secondary lee cyclogenesis event in the Mackenzie River basin. As the secondary disturbance moves to the east, there is a shift in the wind direction that advects air from the Beaufort Sea into the lower laver, This results in a moistening of the lower layer that allows precipitation from the upper layer that had previously evaporated in the lower layer to be enhanced and reach the surface. The detailed structure of this type of storm is strongly affected by the topography of the region and the presence of open water in the southern Beaufort Sea. The storm track weather system is markedly different and is associated with the passage of a mesoscale low over the southern Beaufort Sea. In this sort of system, there is a well-defined frontal structure of a type previously identified in the midlatitudes. Two different precipitation regimes are identified that are associated with the passage of the warm and cold front. Tn this sort of system, the sources of moisture are the Bering Sea and the open water in the southern Beaufort Sea.

Autin, W. J. (1993). "Influences of Relative Sea-Level Rise and Mississippi River Delta Plain Evolution on the Holocene Middle Amite River, Southeastern Louisiana." Quaternary Research 39(1): 68-74.

Baron, J. S., N. L. Poff, et al. (2002). "Meeting ecological and societal needs for freshwater." Ecological Applications 12(5): 1247-1260.

Human society has used freshwater from rivers, lakes, groundwater,, and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilization for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life-and these are costly, if, not impossible, to replace. Long-term benefits include the sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations, such as climate change. Thus, maintenance of the processes and properties that support freshwater ecosystem integrity should be included in debates over sustainable water resource allocation. The purpose of this report is to explain how the integrity of freshwater ecosystems depends upon adequate quantity, quality, timing, and temporal variability of water flow. Defining these requirements in a comprehensive but general manner provides a better foundation for their inclusion in current and future debates about allocation of water resources. In this way the needs of freshwater ecosystems can be legitimately recognized and addressed. We also recommend ways in which freshwater ecosystems can be protected, maintained, and restored. Freshwater ecosystem structure and function are tightly linked to the watershed or catchment of which they are a part. Because riverine networks, lakes, wetlands, and their connecting groundwaters, are literally the "sinks" into 'Which landscapes drain, they are greatly influenced by terrestrial processes, including many human uses or modifications of land and water. Freshwater ecosystems, whether lakes, wetlands, or rivers, have specific requirements in terms of quantity, quality, and seasonality of their water supplies. Sustainability normally requires these systems to fluctuate within a natural range of variation. Flow regime, sediment and organic matter inputs, thermal and light characteristics, chemical and nutrient characteristics, and biotic assemblages are fundamental defining attributes of freshwater ecosystems. These attributes impart relatively unique characteristics of productivity and biodiversity to each ecosystem. The natural range of variation in each of these attributes is critical to maintaining the integrity and dynamic potential of aquatic ecosystems; therefore, management should allow for dynamic change. Piecemeal approaches cannot solve the problems confronting freshwater ecosystems. Scientific definitions of the requirements to protect and maintain aquatic ecosystems are necessary but insufficient for establishing the appropriate distribution between societal and ecosystem water needs. For scientific knowledge to be implemented science must be connected to a political agenda for sustainable development. We offer these recommendations as. a beginning to redress how water is viewed and managed in the United States: (1) Frame national and regional water management policies to explicitly incorporate freshwater ecosystem needs, particularly those related to naturally variable flow regimes and to the linking of water quality with water quantity; (2) Define water resources to include watersheds, so that freshwaters are viewed within a landscape, or systems context; (3) Increase communication and education across disciplines, especially among engineers, hydrologists, economists, and ecologists to facilitate an integrated view of freshwater resources; (4) Increase restoration efforts, using well-grounded ecological principles as guidelines; (5) Maintain and protect the remaining freshwater ecosystems that have high integrity; and (6) Recognize the dependence of human society on naturally functioning ecosystems.

Barras, S. C. and J. A. Kadlec (2000). "Abiotic predictors of avian botulism outbreaks in Utah." Wildlife Society Bulletin 28(3): 724-729.

Avian botulism is a toxicosis responsible for large outbreaks in wild waterfowl and wading birds. The toxin is produced by the bacterium Clostridium botulinum type C. We gathered existing climatological and streamflow data for the Bear River Delta of northeastern Utah to determine effects of environmental factors on probability of occurrence of an avian botulism outbreak. We built a logistic regression model using weather variables and streamflow amounts for 28 years, with a response variable if an outbreak occurred during each year. Winter-summer precipitation amounts and summer streamflow were predictors of outbreak probability (P<0.001). Outbreaks were more likely to occur during years of high winter-summer precipitation and high Bear River flows during summer. We concluded that these outbreak predictors may contribute to water-level fluctuations in managed wetland units, associated previously with outbreaks in this and other systems.

Bauch, H. A. and Y. I. Polyakova (2000). "Late Holocene variations in Arctic shelf hydrology and sea-ice regime: evidence from north of the Lena Delta." International Journal of Earth Sciences 89(3): 569-577.

Diatom assemblage studies are used to interpret past changes in river runoff (salinity) and sea-ice regime in the vicinity of the vast Lena River delta, southern Laptev Sea shelf. On the basis of their distribution in sur face sediments, the shelf region outside the strong influence of riverine waters is characterized by a dominance in sea-ice diatoms and other marine species. Their numbers increase steeply (>20%) within the area of drifting pack ice. In contrast, the marginal zone of the delta, where exceedingly low salinities prevail, is marked by freshwater diatoms showing values higher than 70%. Using the environmental information from the surface sediments, the downcore distribution patterns of the main ecological groups of diatoms were investigated on a sediment core that covers the past 2800 cal. years BP. Although the freshwater group indicates some temporal variations in salinities, the study site north of the Lena River delta remained under a dominantly riverine influence for most of the three recognized phases. In contrast, the relative abundance of sea-ice species gives evidence that pack-ice conditions were more severe during the oldest phase (older than similar to 2700 cal. years BP). The most significant changes are observed in the uppermost core section (younger than similar to 300 cal. years BP) when the relative abundance of freshwater diatoms decreases from 80% down to below 20%. This dramatic decrease is interpreted as a major shift from a more northward-directed to the modern, dominantly eastern outflow pattern. Because the dispersal and fate of riverine waters and its role on the ice regime as well as on water mass properties is a central issue in understanding short- and longer-term climatic changes in the Arctic and beyond, it needs to be tested using more cores if this most recent change in outflow pattern from the delta is connected to climate change or simply a result of channel migration within the delta.

Bellotti, P., C. Caputo, et al. (2004). "Morpho-sedimentary characteristics and Holocene evolution of the emergent part of the Ombrone River delta (southern Tuscany)." Geomorphology 61(1-2): 71-90.

The Holocene evolution of the Ombrone River delta has been investigated using morphological and sedimentological evidence. The delta had a lagoon-like prehistoric evolution, while seawards the growth occurred mainly in historical times. The data obtained, together with the available historical and archeological documentation, enable a quantitative evaluation of the volume of the emerged part of the delta to be made. Moreover, for the apical area, it has been possible to calculate the annual average increase in the volume of deposition during Etruscan and Roman times, as well as during the Middle Ages and since the Renaissance up to now. It has been possible to estimate the periods during which wind exerted a more important role in shaping the delta morphology. The volume of sediments deposited during the last 6000 years has been estimated at 1766(.)10(6) m(3). A combination of climatic conditions, littoral dynamics and human action appears to have driven the dynamics of the delta growth, which, however, was not continuous, but active especially during the last 3000 years. During this period, about the 80% of the whole delta volume seems to have deposited. High rates of sedimentation occurred between the 16th and the 19th centuries (a cold and moist period coinciding with the Little Ice Age), when the delta took the typical shape of microtidal wave-dominated deltas. (C) 2004 Elsevier B.V. All rights reserved.

Boeskorov, G. G. (2004). "The north of Eastern Siberia: Refuge of Mammoth fauna in the Holocene." Gondwana Research 7(2): 451-455.

The global climate changings at the end of Pleistocene led to extinction of the typical representatives of Mammoth fauna-mammoth, woolly rhinoceros, wild horse, bison, muskox, cave lion, etc-on the huge territories of Northern Eurasia. Undoubtedly the Mammoth fauna underwent pressure from the Upper Paleolithic Man, whose hunting activity also could play the role in decreasing the number of mammoths and other representatives of megafauna (large mammals). Archaeological data testify that the typical representatives of Mammoth fauna were the Man's hunting objects only till the end of the Pleistocene. Their bone remains are not usually found on the settlements of Mesolithic Man. Formerly it was supposed that the megafauna of 'Mammoth complex' was extinct by the beginning of Holocene. Nevertheless the latest data testify that the global extinction of the Mammoth fauna was sufficiently delayed in the north of Eastern Siberia. In the 1990s some radiocarbon data testified that the mammoths on the Wrangel Island existed for a long time during the Holocene from 8000 till 3700 y. BR The present radiocarbon data show that wild horses inhabited the north of Eastern Siberia (the lower stream of the Enissey river, the Novosibirskie Islands, the East Siberian sea-shore) 3000-2000 y. BR Musk-oxen lived on the Taimyr Peninsula and the Lena River delta about 3000 y. BR Some bison remains from Eastern Siberia belong to the Holocene. The following circumstances could promote the process of preservation of the Mammoth fauna representatives. The cool and dry climate of this region promotes the maintenance of steppe associations - habitats of those mammals. The Late Paleolithic and Mesolithic settlements are not found in the Arctic zone of Eastern Siberia from the Taimyr Peninsula to a lower stream of the Yana River; they are very rare in the basins of the Indigirka and Kolyma Rivers. So, the small number of the Stone Age hunting tribes on the North of Eastern Siberia was another factor in the long-term preservation of some Mammoth fauna representatives.

Cattaneo, A., A. Correggiari, et al. (2003). "The late-Holocene Gargano subaqueous delta, Adriatic shelf: Sediment pathways and supply fluctuations." Marine Geology 193(1-2): 61-91.

The Gargano subaqueous delta formed on the eastern and southeastern sides of the Gargano promontory, in the western Adriatic. This subaqueous deposit represents the southernmost portion of the late-Holocene highstand systems tract (HST) growing along the western side of the Adriatic as an extensive wedge of deltaic and shallow-marine mud. The late-Holocene HST rests above a regional downlap surface that marks the time of maximum landward shift of the shoreline attained around 5.5 cal. kyr BP, at the end of the late-Pleistocene-Holocene sea-level rise. High-resolution seismic-stratigraphic and tephra correlation indicate the presence of a thin basal unit recording condensed deposition between 5.5 and 3.7 cal. kyr BP over much of the basin. Above this unit, sediment accumulation rates increased to high values (as much as 1.5 cm yr(-1)) reflecting the stabilisation of relative sea level and the forcing from high frequency climatic or anthropogenic changes affecting river dynamics. The late-Holocene mud wedge, of which the Gargano subaqueous delta is a significant component, reaches up to 35 in in thickness and has a volume of ca 180 km(3). The shore-parallel thickness distribution of the mud wedge reflects the dominant oceanographic regime of the basin and the asymmetric location of the mostly western sediment sources (with a combined modern delivery of 51.7x10(6) t yr(-1) of mean suspended load). In sections perpendicular to the coast the late-Holocene mud wedge appears composed of forestepping clinoforms with gently dipping foresets (typically 0.5degrees). The Gargano subaqueous delta is characterised by a submarine topset in water depths shallower than 25-28 m, and accounts for about 1/7th of the total volume of the late-Holocene mud wedge, despite the absence of direct river supply to the Gargano area. In the area of maximum interaction between shore-parallel currents and basin morphology, progradation occurs onto a flat and barren bedrock outcrop in about 50-80 m water depth. The rapid transition from a thickness of 30 m of late-Holocene mud to nil is a good indication of the role of southward-flowing bottom-hugging shelf currents in causing the redistribution of sediment along the Adriatic inner shelf. Additional evidence of this regime comes from: (1) the most recent sigmoid (defined at seismic-stratigraphic scale) deposited since the onset of the Little Ice Age, showing a shore-parallel thickness distribution and a main depocentre to the southeast of the Gargano promontory; (2) the maximum values of sediment accumulation rates over the last century (documented by Pb-210 measurements) defining a narrow shore-parallel belt immediately seaward of the depocentre of the most recent sigmoid. The Gargano subaqueous delta grows from the outbuilding of progressively younger progradational sigmoids that tend to parallel the previous ones. The Gargano subaqueous delta differs from other, documented late-Holocene subaqueous deltas because its growth reflects: (1) sediment transport dominated by bottom currents sub-parallel to the strike of the composing clinoforms; (2) a complex supply regime including the Po delta (350 km to the north) and several coalescing Apennine rivers acting as 'line source', (3) several alternating intervals of enhanced outbuilding and condensed depositions and (4) an in-phase growth of the most recent sigmoid with the major progradation of the Po delta during the Little Ice Age. (C) 2002 Elsevier Science B.V. All rights reserved.

ChagueGoff, C. and W. S. Fyfe (1996). "Geochemical and petrographical characteristics of a domed bog, Nova Scotia: A modern analogue for temperate coal deposits." Organic Geochemistry 24(2): 141-158.

A freshwater domed bog in Nova Scotia, Canada, was investigated for its petrographic, mineralogical and geochemical characteristics. Three cores were taken from the lagg zone, margin and centre, to examine different stages of evolution in a fen to domed bog sequence. Based on this study, a model was developed, which shows the relationship between factors controlling peat geochemistry and petrography, all of them being dependent on trophic conditions. The bog may represent a modern analogue for temperate coal deposits, and thus can be used to help understand spatial variability within coal beds. Rheotrophic conditions in the early stages of mire development result in the formation of high-ash, highly humified Caret-dominated peat, while the evolution toward ombrotrophic conditions is reflected in a progressive replacement by low-ash and well-preserved Sphagnum-dominated peat. The associated decrease in pH reflects a decrease of groundwater influence, which is also supported by the mineralogical assemblage and petrographic data (decrease in reflectance and change in maceral composition). Except for Cl, Br, I and Se, which are associated with the organic fraction, variations in elemental composition can be explained in terms of mineral matter abundance, i.e. decrease upward and with increasing distance from the margin. Sea spray is the most probable origin for halogen enrichment in the pear. Copyright (C) 1996 Elsevier Science Ltd

Chan, C. Y. and L. Y. Chan (2000). "Effect of meteorology and air pollutant transport on ozone episodes at a subtropical coastal Asian city, Hong Kong." Journal of Geophysical Research-Atmospheres 105(D16): 20707-20724.

Hong Kong is a subtropical coastal city situated at the rapid urbanizing and industrializing region of South China. High frequencies of elevated ozone are found in various remote, rural, and metropolitan districts of Hong Kong. Meteorological conditions related to synoptic-scale flow pattern, mesoscale weather phenomenon, and local micrometeorology have strong effects on the pollutant transport to South China and the occurrence of ozone episodes in Hong Kong. The transport processes and the source regions of ozone are analyzed with the combined use of surface pressure patterns, streamline charts and prevalent winds, and with representative episodes. The synoptic meteorological conditions can be classified into nine patterns. The patterns associated with winter monsoon and traveling cyclones are found to be most conducive to the occurrence of ozone episodes. Long-range transport of ozone with enhanced CO level from the aged continental air accompanying northeast monsoon contributes to substantial cases of episodes, which are especially noticeable in the upwind remote areas. These episodes feature consistently high ozone at night in the remote station and early morning peaks in the metropolitan stations. The possible source regions of this ozone may include Asian continent, the coastal areas of Mainland China, southern Japan, and Taiwan. This high inflow of background ozone together with elevated ozone enhanced by the channeling effect, and local transport causes the highest frequencies of ozone episodes in the downwind western side of the territory. The short-range transport of ozone and pollutants from the industrial and urban centers in the Pearl River Delta region and Guangdong Province in southern China is another source of ozone. When transported ozone is being superimposed on ozone formed from local sources, territory-wide and extremely high concentration episodes are found. Our meteorological and ozone episode diagnosis have also demonstrated that the 'background' outflow of Asian pollutants can be significantly modified on its way to the Pacific Ocean when passing through the fast growing Pearl River Delta cities such as Hong Kong.

Chang, W. Y. B. (1997). "ENSO: Extreme climate events and their impacts on Asian deltas." Journal of the American Water Resources Association 33(3): 605-614.

Proxy climate data for the last 500 years collected from the archives of counties in the Yangtze River Delta, China, were analyzed to identify the occurrence of extreme climate events, the pattern of such occurrences and their relationships to El Nino Southern Oscillation (ENSO). This study identified the cycle periods of 3.5, 5.5 and 8.6 years for floods and 18.5 years for droughts in the Yangtze River Delta during the last 500 year period and noted 16 regional (delta wide) extreme events during this period. All regional (delta wide) extreme climate events during the last 500 years (since 1500 A.D.) occurred either during or immediately after ENSO (5-6 year) activities. Hydrological impacts of extreme climate events, such as major floods and droughts, on human systems have long been among the foremost concerns of the Pacific Rim countries. Management of systems increasingly dominated by humans, such as Asian delta regions, should, therefore, include consideration of major climate variability, ENSO events and the extent of climate changes, as well as consideration of the trends associated with human growth and institutional changes.

Chauvelon, P., M. G. Tournoud, et al. (2003). "Integrated hydrological modelling of a managed coastal Mediterranean wetland (Rhone delta, France): initial calibration." Hydrology and Earth System Sciences 7(1): 123-131.

This paper presents a model of a heavily managed coastal Mediterranean wetland. The hydrosystent studied, called "Ile de Camargue", is the central part of the Rhone river delta. It comprises flat agricultural drainage basins, marshes, and shallow brackish lagoons whose connection to the sea is managed. This hydrosystem is subject to strong natural hydrological variability due to the combination of a Mediterranean climate and the artificial hydrological regime imposed by flooded rice cultivation. To quantify the hydrological balance at different spatial and temporal scales, a simplified model is developed - including the basin and the lagoons - using a time step that enables the temporal dynamic to be reproduced that is adapted to data availability. This modelling task takes into account the functioning of the natural and anthropogenic components of the hydrosystem. A conceptual approach is used for modelling drainage from the catchment, using a GIS to estimate water input for rice irrigation. The lagoon system is modelled using a two-dimensional finite element hydrodynamic model. Simulated results from the hydrodynamic model run under various hydro-climatic forcing conditions (water level, wind speed and direction, sea connection) are used to calculate hydraulic exchanges between lagoon sub units considered as boxes. Finally, the HIC ("Hydrologie de I'lle de Camargue") conceptual model is applied to simulate the water inputs and exchanges between the different units, together with the salt balance in the hydrosystem during a calibration period.

Cohen, A. D. and E. M. Stack (1996). "Some observations regarding the potential effects of doming of tropical peat deposits on the composition of coal beds." International Journal of Coal Geology 29(1-3): 39-65.

Several important concepts relative to the origin of coal beds can be gleaned from studies of modern domed and planar peat deposits in tropical-subtropical settings. These are: (1) laterally, some portions of a single continuous peat deposit may be domed and some portions may be planar; (2) domed deposits are most often found to have begun as planar deposits; (3) domed-formed peat facies may be overridden by planar-formed peat facies, due to such factors as sea level rise and/or increased rate of local and basinal subsidence; (4) domed peat facies tend to have less mineral matter and contain fewer inorganic splits than planar facies; (5) sulfur intrusion from marine waters can be retarded by doming, allowing low-sulfur peats to form relatively near to the coastline; (6) marine transgression can cause high-sulfur, marine-influenced, planar, peat facies to override freshwater domed or planar facies, resulting in enrichment of the upper parts of these underlying facies in sulfur and ash; (7) dome-formed peat facies tend to be thicker and more uniform in composition than planar-formed facies, with dome-formed peat facies having the potential to produce the more uniform bright coal types (clarains and vitrains) and planar-formed pear facies often producing duller coal types and/or alternating, durainic (inertinite-rich) and vitrainic (wood-derived) bands; (8) actively developing peat domes in wet settings often exhibit no appreciable increase in inertinitic material toward their tops; although the tops of either domed or planar peat deposits can be enriched in inertinitic material if the water table is lowered by either local or regional changes in hydrology or climate.

Correggiari, A., F. Trincardi, et al. (2001). "Styles of failure in late Holocene highstand prodelta wedges on the Adriatic shelf." Journal of Sedimentary Research 71(2): 218-236.

On the continental shelves of the northern Mediterranean basin, the late Holocene highstand systems tract (HST) prograded under the influence of major rivers, after the attainment of the present sea-level highstand (about 5.5 cal kyr BP), On the Adriatic shelf, the thickness distribution of the late Holocene HST reflects the location of major deltas on the western side of the basin and the geostrophic circulation, which prevents a more uniform sediment dispersal toward the center of the basin. Very high sediment accumulation rates (1 to 10 cm/year) resulted in the construction of a HST depocenter up to 35 m thick. This shore-parallel depocenter is affected by failure of limited displacement over as much as 40% of its extent, Gas impregnation is common in the topset region and occurs at very shallow levels (a few meters) below the sea floor, Five areas are characterized by a variety of sea-floor and subsurface crenulations. Although locally some of these crenulations have an intriguingly regular geometry, sediment failure is the most plausible mechanism for their formation. Sediment failure better explains the large variety of geometries that characterizes the coastal mud prism of the late Holocene HST. Furthermore, we observe that these crenulations occur only where the downlap surface at the base of the HST is disrupted and affected by geometries that are consistent with fluid escape processes, This relationship suggests that the basal surface acts as a weak layer for sediment failure. Failure occurred in variable water depths from the northern slope of the modern Po prodelta (10-20 m water depth) to the narrow shelf offshore Bari (40-110 m water depth). In all these areas the proximal part of the HST prodelta wedge is intensely gas-charged. The thickness and age of the sediment sections affected by failure are slightly different from place to place but appear everywhere younger than 5.5 cal kyr BP, Where failure affects the entire HST the detachment occurs on the downlap surface at its base, Failure geometries characterize the head region whereas compressional features, such as pressure ridges and mud diapirs, dominate in the toe region, ranging in depth between 70 and 110 m, Where failure is limited to the upper few meters of the HST, there is a clear lithologic change (decrease in carbonate fraction and grain size) across the basal surface. This lithological change reflects a switch in sediment supply from local Apennine rivers (below) to Po-derived mud; this change occurred at the onset of the Little Ice Age, documenting the indirect control of short-term climate change and human impact on sediment architecture. The deformations affecting the late Holocene HST in the various areas show differences in internal geometry, but appear everywhere to be characterized by limited downward displacement and can be attributed to shear-dominated retrogressive failure. It is suggested that some degree of consolidation occurred immediately after mobilization, possibly induced by the escape of fluids, Nowhere has failure evolved into disintegration and flow, likely because the type of cyclic loading that triggered it was not prolonged over a long enough interval. Short-lived radionuclides in the uppermost stratigraphic layers, which postdate the failure in the area offshore Ortona, allowed us to quantify systematic changes in sediment accumulation rates as a function of the underlying deformed sea floor. In areas of wavy sea floor, troughs show sediment accumulation rates of greater than 16 mm/yr, a figure that is fourfold the rate measured on the flanks of the troughs. These values document a complex feedback between sea-floor roughness initially caused by failure and subsequent sedimentation.

Dheeradilok, P. (1995). "Quaternary Coastal Morphology and Deposition in Thailand." Quaternary International 26: 49-54.

Thailand is part of the Asian continent that is generally considered to be tectonically stable compared to adjacent regions in southeastern Asia. However, studies of Quaternary stratigraphic sequences, depositional processes and coastal morphology of the Thailand coast, have provided evidence of continuing Cenozoic epeirogenic movement influencing coastal evolution. These movements have affected coastal and river depositional responses to climate and eustatic sea level change. The Quaternary marine formations are extensive along the coastal zone for a distance of about 1850 km in the Gulf of Thailand and occur sporadically along the 865 km west coast of the Thai Peninsula. On the Thai Peninsula, the emergence of the west coast has resulted in the formation of numerous islands, drowned valleys, short and narrow beaches and truncated headlands, in the high energy coastal erosion regime of the Andaman Sea. Steep-gradient, short rivers form floodplains of comparatively thin deposits of Quaternary sediments, and narrow bays backed by crescent shape sand ridges. This contrasts with the east coast where thick sequences of Quaternary fluvial and deltaic aggradational deposits, and Holocene progradational beaches, sand spits, tidal flats and lagoons, are indicative of tectonic subsidence with a coastal current transporting sediment into the region. Along the coastal Central Plain, the Chao Phraya delta is underlain by a thick Plio-Pleistocene deltaic and coastal marine sedimentary sequence. This has accumulated in a basin where the Quaternary tectonic environment is affected by epeirogenic uplift of the western highlands and tilting of the Central Plain. At the western Central Plains margin, rivers have formed distinct alluvial fans while the rest of the coastal plain has landscape features formed in the river delta-prograding coast environment that preceded the postglacial marine transgression.

Duvail, S. and O. Hamerlynck (2003). "Mitigation of negative ecological and socio-economic impacts of the Diama dam on the Senegal River Delta wetland (Mauritania), using a model based decision support system." Hydrology and Earth System Sciences 7(1): 133-146.

The delta of the River Senegal was modified substantially by the construction of the Diama dam in 1986 and the floodplain and estuarine areas on the Mauritanian bank were affected severely by the absence of floods. In 1994, managed flood releases were initiated in the Bell basin (4000 ha) of the Diawling National Park, as part of a rehabilitation effort. The basin was designated as a joint management area between traditional users and the Park authority and a revised management plan was developed through a participatory approach based on a t opographical. hydro-climatic, ecological and socio-economic data. Hydraulic modelling was developed as a tool to support stakeholder negotiations on the desired characteristics of the managed flood releases. Initially, a water balance model was developed. The data were then integrated into a one-dimensional hydraulic model, MIKE 11 (DHI, 2000). When associated with a Digital Elevation Model and a Geographic Information System, (Arc View), the model provided a dynamic description of floods. Flood extent, water depth and flood duration data were combined with ecological and socio-economic data. The water requirements of the different stakeholders were converted to flood scenarios and the benefits and constraints analysed. A consensus scenario was reached through a participatory process. The volume of flood release required to restore the delta does not affect hydro-power generation, navigation or intensive irrigation, for which the dams in the basin were constructed. Hydraulic modelling provided useful inputs to stakeholder discussions and allows investigation of untested flood scenarios.

Feder, H. M., D. W. Norton, et al. (2003). "A review of apparent 20th century changes in the presence of mussels (Mytilus trossulus) and macroalgae in Arctic Alaska, and of historical and paleontological evidence used to relate mollusc distributions to climate change." Arctic 56(4): 391-407.

Live mussels attached to fresh laminarioid brown algae, all fastened to clusters of pebbles and small cobbles, were repeatedly cast ashore by autumn storms at Barrow, Alaska, in the 1990s. Specimens of Laminaria saccharina and L. solidungula shorten by 100 km a 500 km gap (Peard Bay to Stefansson Sound) between previously known concentrations of these kelp species. For the genus Mytilus, a 1600 km gap in fully documented locations existed between Kivalina in the southern Chukchi Sea and the Mackenzie River delta. Barrow specimens were identified using a mitochondrial DNA marker as M. trossulus, an identity consistent with dispersal: from the Pacific-Bering side of the Arctic. Live mussels and macroalgae were neither washed up by storms nor collected by active biological sampling during extensive benthic surveys at Barrow in 1948-50. We cannot interpret the current presence of these bivalves and. macrophytes as Arctic range extensions due to warming, similar to those manifested by the tree line in terrestrial systems and by Pacific salmon in marine environments. Supplemental information and critical evaluation of survey strategies and rationales indicate that changes in sea temperatures are an unlikely cause. Alternative explanations focus on past seafloor disturbances, dispersal from marine or estuarine refugia, and effects of predators on colonists. This review suggests refining some interpretations of environmental change that are based on the extensive resource of Cenozoic fossils of Arctic molluscs.

Fedorov, K. N., N. V. Stasyuk, et al. (1996). "Specific features of modern soil formation in the Caspian lowland." Eurasian Soil Science 29(4): 452-458.

Two problems are considered: (a) syngenesis and genetically bound evolution of soils and relief of water-accumulative plains in the western part of the Caspian Lowland and (b) spatial and temporal dynamics and its forecast of salinization of the Terek river delta. Three separate, though genetically linked, evolution cycles are shown to occur in conditions of relatively stable climate, ground water level, and topography of water-accumulative plains in arid regions. The major features and parameters of spatial and temporal dynamics of salinization of the Terek delta are established. The forecast of this process for the period up to 2029 is worked out.

Feng, G. L., W. J. Dong, et al. (2004). "On temporal evolution of precipitation probability of the Yangtze River delta in the last 50 years." Chinese Physics 13(9): 1582-1587.

The monthly precipitation observational data of the Yangtze River delta are transformed into the temporal evolution of precipitation probability (PP), and its hierarchically distributive characters have been revealed in this paper. Research results show that precipitation of the Yangtze River delta displays the interannual and interdecadal characters and the periods are all significant at a confidence level of more than 0.05. The interdecadal is an important time scale, because it is on the one hand a disturbance of long period changes, and on the other hand it is also the background for interannual change. The interdecadal and 3-7y oscillations have different motion laws in the data-based mechanism self-memory model (DAMSM). Meanwhile, this paper also provides a new train of thought for dynamic modelling. Because this method only involves a certain length of data series, it can be used in many fields, such as meteorology, hydrology, seismology, and economy etc, and thus has a bright perspective in practical applications.

Fontes, J. C., J. N. Andrews, et al. (1991). "Paleorecharge by the Niger River (Mali) Deduced from Groundwater Geochemistry." Water Resources Research 27(2): 199-214.

Stable isotopes, major elements, trace elements, and noble gases in groundwater from northern Mali permit a reconstruction of the paleohydrology of the Sahelian and sub-Saharan regions of west Africa. Major floods of the Niger River during the more humid episodes of the Holocene, probably associated with northward migration of the interior river delta (flood zone), were responsible for groundwater recharge. A marine aerosol imput, somewhat modified by rock-water interaction, dominates the groundwater chemistry. Stable isotope compositions distinguish the Saharan zone groundwater from waters recharged in the Sahelian zone south of the Azaouad ridge. Carbon 14 dating shows that whereas the latter are modern, the Saharan zone was recharged in the Early to Middle Holocene. Noble gas contents suggest that recharge north of Azaouad occurred under cooler climatic conditions than presently prevail.

Gambolati, G., P. Teatini, et al. (1999). "Coastline regression of the Romagna region, Italy, due to natural and anthropogenic land subsidence and sea level rise." Water Resources Research 35(1): 163-184.

The Romagna coastal area in the Northern Adriatic Sea has experienced in recent times continuous changes because of its precarious environment and low ground elevation above mean sea level (msl). Major processes that may influence the stability of the coast profile include land subsidence of both natural and anthropogenic origin and the msl rise caused by global climate change. According to the most accredited modeling predictions msl is expected to rise by almost 0.5 m over the next century because of the greenhouse effect. Natural land subsidence is the result of deep downward tectonic movement and consolidation of geologically recent deposits. It may be estimated in the range of 2-2.5 mm/yr in the Ravenna area and twice as much in the Po River delta. Anthropogenic land subsidence is primarily related to groundwater pumping from the upper fresh water aquifer system and gas production from Plio-Pleistocene reservoirs. Geodetic surveys from 1953 to 1990 provide documentary evidence of cumulative land settlement exceeding 0.8 m and 1.2 m at Marina di Ravenna and Cesenatico, respectively. In this study we estimate both natural and anthropogenic land subsidence for the years 2015, 2050, and 2100 with the aid of ad hoc finite element simulation models. The use of these predictions together with the expected msl rise shows that many present lowlands may be permanently submerged at the end of the next century. The extent of the flooded area of the Romagna coastal region can be as much as 690 and 910 km(2), using optimistic and pessimistic land subsidence scenarios, respectively. A local detailed analysis indicates that the areas around the cities of Ravenna and Cesenatico may be seriously affected by sea water ingression while the city of Rimini is well protected because of its relatively high elevation above msl.

Gambolati, G., P. Teatini, et al. (2002). "GIS simulations of the inundation risk in the coastal lowlands of the Northern Adriatic Sea." Mathematical and Computer Modelling 35(9-10): 963-972.

The Northern Adriatic Coastland, between the cities of Monfalcone and Cattolica, is characterized by locations of great tourist interest, such as the Venice Lagoon and the Romagna Riviera, and areas with a very precarious environmental setting, such as the Valli di Comacchio, and the Po River Delta. Therefore, the coastal management and the design of new defence works of the littoral have to be made with the utmost care, possibly with the aid of numerical predictions of the coastal morphodynamics and the flood risk analysis of the lowland involved. In the study area, land may subside due to sediment natural compaction and subsurface fluid (water and gas) withdrawal. At the same time, littoral transport of solid material can contribute appreciably to change the shore morphology. Mean sea level may rise permanently due to global climate change (eustatism) and occasionally due to tides and intensive storm events. The predictions of each individual process is obtained using various ad hoc mathematical models and the outcome of the numerical simulations are managed with a GIS (geographical information system). Coastline evolution until the year 2100 is investigated and risk factor maps of the low-lying coastal areas are generated which account for the hazard of the expected event, and the land economic value and vulnerability. (C) 2002 Elsevier Science Ltd. All rights reserved.

Giordani, P., W. Helder, et al. (2002). "Gradients of benthic-pelagic coupling and carbon budgets in the Adriatic and Northern Ionian Sea." Journal of Marine Systems 33: 365-387.

The Adriatic sea is generally viewed as a long bay in the Central Mediterranean, stretching SE to NW for 800 km, from the Strait of Otranto to the Gulf of Venice, with an extremely long, geometrically complex coastline, creating a high diversity of hydrodynamic and sedimentary environments. The seafloor slopes down from the North shallow shelf (mean depth 35 in) through the middle Adriatic depression (250 in depth in the Pomo Pit) to the bathyal reached in the Southern Adriatic pit (1260 in). Typical physiographic and climatic features strongly influence biological productivity. The productivity of the Northern Adriatic is among the highest in the Mediterranean, while it becomes lower in the offshore waters of the Central and Southern subbasins, defining clear oligotrophic and benthic-pelagic coupling gradients from the Northern to the Southern edge of the basin. Assessing the benthic response to particulate fluxes of organic matter from the photic layer was a target of the EU-MATER Project. The applied methodological strategy involved measurements of primary production by C-14 in situ incubation technique, of particulate fluxes through the water column by moored sediment traps, of sediment community oxygen consumption (SCOC) by in situ and on-deck incubations, and of carbon burial fluxes at three sites in the Southern Adriatic (Al), the Otranto Strait (02) and the Ionian sea (11), along the main pathway of outflowing water masses. In this paper, yearly budget calculations of carbon are presented for stations, selected as being representative of wider areas in the three subbasins, to give a picture of the Adriatic basin as a whole. Data from the Northern basin, obtained by the same methodology, come from previous research programmes carried out in the framework of EU Marine projects (STEP/Adria and MTP 1/Euromarge AS). The carbon fraction reaching the seafloor was quantified as the sum of SCOC and burial fluxes and was compared to 14C primary production measurements in the photic zone. Both primary production estimates and carbon respired in the sediment (SCOC) show a clear depth dependence, with the former ranging between 588 g C m(-2) year(-1) in the Northern shelf off the Po river delta, and 62 g C m(-2) year(-1) in the Ionian sea, and the latter between 130 and 2 g C m(-2) year(-1) at the same sites. Burial efficiencies (the ratios of buried carbon to carbon rain) decrease from 47% to 3%. Sediment organic matter lability was investigated through its composition in terms of proteins, lipids and carbohydrates and the sum of their concentrations as expressed in carbon equivalents (biopolimeric carbon fraction, BPC). Compositional differences are clearly indicated between the Northern and the Middle-South Adriatic subbasins due to mixing with terrestrial carbon in the North and longer residence times in the water column in the Middle-South, with the Pomo Pit representing an accumulating site of refractory organic carbon. From carbon budget calculations for the deep sites, taking into account trap measured fluxes to the sediment, lateral input seems to play a role at the deep sites and especially in the Pomo Pit. (C) 2002 Elsevier Science B.V. All rights reserved.

Goodbred, S. L. and S. A. Kuehl (2000). "Enormous Ganges-Brahmaputra sediment discharge during strengthened early Holocene monsoon." Geology 28(12): 1083-1086.

Rivers are the main source of terrigenous sediment delivered to continental margins and thus exert a major control on coastal evolution and sequence development. However, little is known about past changes in fluvial sediment loads despite the recognition of significant variation under changing climatic regimes. In this study we present the first quantified estimate of sediment discharge for a major river system under conditions of an intensified early Holocene monsoon. Development of the Ganges-Brahmaputra River delta began ca. 11 000 yr B.P., when rising sea level flooded the Bengal basin, thereby trapping most of the river's discharge on the inner margin. Chronostratigraphic data from these deltaic deposits are used to calculate the rates of sediment storage on the margin, which provide a minimum estimate of the river's past sediment load. Results reveal that similar to5 x 10(12) m(3) of sediment was stored in the Bengal basin from ca, 11 000 to 7000 yr B.P., which corresponds to a mean load of 2.3 x 10(9) t/yr. In comparison, modern sediment load of the Ganges-Brahmaputra is similar to1 x 109 t/yr, ranking it first among the world's rivers and underscoring the significance of a two-fold increase sustained over 4 k.y. Furthermore, the timing of immense discharge in the early Holocene strongly suggests its relation to a stronger than present southwest monsoon in South Asia. Similar patterns of high monsoon-related sediment discharge have been noted throughout the tropics and subtropics, suggesting a widespread fluviosedimentary response, the potential magnitude of which is show-cased by the Ganges-Brahmaputra system.

Goodbred, S. L. (2003). "Response of the Ganges dispersal system to climate change: a source-to-sink view since the last interstade." Sedimentary Geology 162(1-2): 83-104.

The forcing of sediment dispersal systems by climate is widely accepted, but there remains disagreement on the general responses to climate change, such as how resulting signals propagate downstream and, ultimately, how they are preserved in the stratigraphic record. Towards a better understanding of these issues, this paper presents a comprehensive overview of Ganges dispersal system behavior since the last interstade, which reveals major, coeval responses to changes in the South Asian monsoon. At >3000 km from its mountain headwaters to deep-sea fan, the Ganges dispersal system is immense and yet shows tight coupling between source area, catchment basin and coastal and marine depocenters. Furthermore, system-wide responses and downstream transfer of the signal appear to occur at least as fast as current temporal resolution of 1-2 ky. This tight linkage of source-to-sink components is considered a function of the southwest (summer) monsoon's overwhelming control on regional hydrology. About 80% of the Ganges discharge and 95% of its sediment load are delivered to the margin during only 4 months, making the system extremely sensitive to this seasonal forcing. In addition, the regional scale and distribution of the monsoon weather system means that changes in atmospheric circulation affect the entire drainage basin rather than local subcomponents. Finally, despite its present intensity, strength of the summer monsoon has varied significantly over the past 150 ky under orbitally driven changes in insolation and global (glacial) boundary conditions. The resulting changes in precipitation, both well above and below modem values, have forced system-wide responses ranging from glacier advance/retreat to sediment fluxes to the margin and deep-sea fan. The overall conclusions are (1) that this immense dispersal system responds to multimillennial-scale (< 10(4) years) climate change in a system-wide and largely contemporaneous manner and (2) that major sedimentary signals can be transferred rapidly from source to sink with little apparent attenuation. Furthermore, these acute responses to climate change have produced sedimentary/stratigraphic features that diverge from traditional sequence models in their nature and timing. (C) 2003 Elsevier B.V. All rights reserved.

Haefele, S. M., M. C. S. Wopereis, et al. (2001). "Improving the productivity and profitability of irrigated rice production in Mauritania." European Journal of Agronomy 14(3): 181-196.

Yield, input use, productivity and profitability of irrigated rice in Mauritania were analyzed during the 1997 wet season (July-December) in the Senegal river delta and middle valley, in collaboration with 42 large farmers and extension staff. Objectives were to determine agronomic constraints to rice cropping and to evaluate alternative crop management strategies aimed at overcoming these constraints. Grain yields ranged from 0.9 to 8.5 t ha(-1) and averaged 4.4 t ha(-1). Based on crop simulations, average yield potential in farmers' fields was estimated at 8.6 t ha(-1) indicating considerable scope for increased yields. Our survey identified the following main agronomic constraints: (i) mismatches between timing of nitrogen (N) fertilizer applications and critical N demanding growth stages of the rice plant; (ii) non-use of phosphorus (P) fertilizer on P deficient soils; (iii) largely neglected or inefficient weed management and (iv) late harvesting, often due to non-availability of combine harvesters. Based on these results we tested improved nutrient and weed management practices with farmers during the 1998 wet season. Improved nutrient management (i.e. T1: application of 20 kg P ha(-1) and 150 kg N ha(-1) in three splits at start tillering, panicle initiation and booting) increased yields by 0.9 t ha(-1). Improved weed management (i.e. T2: application of 6.0 L propanil ha (1) and 2.0 L 2,4-D-amine ha (1) at :2-3 leaf stage of weeds) also raised yields by 0.9 t ha(-1) as compared to farmers' practice (TP). The combined effect of T1 and T2 (i.e. T3) was additive: improving both nutrient and weed management raised yields by 1.8 t ha (1) over average farmers' yields of 3.9 t ha (1), i.e. an increase of almost 50%. The improved crop management practices were highly profitable: compared to farmers' practice, net benefits increased by 40% for T1 and T2 and by about 85%, for T3, with minimal additive investments. Inputs used for T3 are relatively easily available in Mauritania. We concluded that increased farmer awareness of the profitability of improved nutrient and weed management may have a tremendous impact on the competitiveness of rice production in Mauritania (C) 2001 Elsevier Science B.V. All rights reserved.

Hori, K., Y. Saito, et al. (2001). "Sedimentary facies and Holocene progradation rates of the Changjiang (Yangtze) delta, China." Geomorphology 41(2-3): 233-248.

The Changjiang (Yangtze) River, one of the largest rivers in the world, has formed a broad tide-dominated delta at its mouth during the Holocene sea-level highstand. Three boreholes (CM97, JS98, and HQ98) were obtained from the Changjiang delta plain in 1997-1998 to clarify the characteristics of tide-dominated delta sediments and architecture. Based on sediment composition and texture, and faunal content, core sediments were divided into six depositional units. In ascending order, they were interpreted as tidal sand ridge, prodelta, delta-front, subtidal to lower intertidal flat, upper intertidal flat, and surface soil deposits. The deltaic sequence from the prodelta deposits to the delta front deposits showed an upward-coarsening succession, overlain by an upward-fining succession from the uppermost part of the delta front deposits to the surface soil. Thinly interlaminated to thinly interbedded sand and mud (sand-mud couplets), and bidirectional cross laminations in these deposits show that tide is the key factor affecting the formation of Changjiang deltaic facies. Sediment facies and their succession combined with AMS C-14 dating revealed that isochron lines cross unit boundaries clearly, and delta progradation has occurred since about 6000 to 7000 years BP, when the rising sea level neared or reached its present position. The average progradation rate of the delta front was approximately 50 km/kyear over the last 5000 years. The progradation rate, however, increased abruptly ca. 2000 years BP, going from 38 to 80 km/kyear. The possible causes for this active progradation could have been an increase in sediment production in the drainage basin due to widespread human interference and/or decrease in deposition in the middle reaches related to the channel stability caused by human activity and climatic cooling after the mid-Holocene. (C) 2001 Elsevier Science B.V. All rights reserved.

Horton, B. P., R. J. Edwards, et al. (1999). "A foraminiferal-based transfer function: Implications for sea-level studies." Journal of Foraminiferal Research 29(2): 117-129.

A dataset consisting of 165 contemporary foraminiferal samples and associated tide level information was compiled by combining data from ten intertidal study areas situated on the east, south and west coasts of the UK, The relationship between the foraminiferal data and a series of environmental variables (elevation, pH, salinity, substrate and vegetation cover) are examined using canonical correspondence analysis (CCA) and partial CCA, To facilitate comparisons between study areas with different tidal ranges, the elevational data are expressed as a standardised water level index (SWLI), The foraminiferal distributions show a strong and highly statistically significant relationship with SWLI. A predictive transfer function has been developed for SWLIs using weighted averaging calibration with inverse and classical deshrinking regression (inverse r(jack)(2) = 0.74; classical r(jack)(2) = 0.75). Statistical measures assessing the performance of this model suggest that reliable reconstructions of former sea levels are possible. The transfer function has important implications for establishing continuous records of relative sea-level change or sedimentation.

Hoy, R. G. and K. D. Ridgway (2003). "Sedimentology and sequence stratigraphy of fan-delta and river-delta deposystems, Pennsylvanian Minturn Formation, Colorado." Aapg Bulletin 87(7): 1169-1191.

Fan-delta and river-delta strata of the middle Pennsylvanian Min-turn Formation were deposited in the Central Colorado trough and are well exposed in the Sangre de Cristo Mountains. Proximal fandelta strata were deposited in lowstand, transgressive, and highstand systems tracts, whereas distal fan-delta strata were deposited in lowstand, highstand, and forced regressive systems tracts. Fan-delta strata were deposited adjacent to coeval westward-dipping thrust faults along the western margin of the Central Colorado trough. Inferred high subsidence rates caused by thrust loading along the western margin of the basin created, accommodation space closer to the basin margin and resulted in localized aggradation. of fan-delta deposits. Proximal river-delta strata were deposited in transgressive, highstand, and early regressive systems tracts, whereas distal river-delta strata were deposited during all stages of sea level change. River-delta deposystems are interpreted to have formed in parts of the basin that experienced relatively less subsidence associated with Pennsylvanian thrust loading. Lower subsidence rates associated with river-delta deposystems resulted in progradation into more distal parts of the basin. Results of our study point out that lateral changes in depositional systems, related to local variation in tectonic subsidence, may produce significant along-strike differences in the sequence stratigraphic, framework of flexural basins. Our analysis also shows that potential reservoir facies in coeval fan-delta and river-delta deposystems form at different times and in different parts of the basin during sea level fluctuation.

Jassby, A. D., J. E. Cloern, et al. (2002). "Annual primary production: Patterns and mechanisms of change in a nutrient-rich tidal ecosystem." Limnology and Oceanography 47(3): 698-712.

Although nutrient supply often underlies long-term changes in aquatic primary production, other regulator processes can he important. The Sacramento-San Joaquin River Delta, a complex of tidal waterways forming the landward portion of the San Francisco Estuary, has ample nutrient supplies, enabling us to examine alternate regulatory mechanisms over a 21-yr period. Delta-wide primary productivity was reconstructed from historical water quality data for 1975-1995. Annual primary production averaged 70 C m(-2), but it varied by over a factor of five among years. At least four processes contributed to this variability: (1) invasion of the clam Potamocorbula amurensis led to a persistent decrease in phytoplankton biomass (chlorophyll a) after 1986: (2) a long-term decline in total suspended solids-probably at least partly because of upstream dam construction-increased water transparency and phytoplankton growth rate: (3) river inflow, reflecting climate variability, affected biomass through fluctuations in flushing and growth rates through fluctuations in total Suspended solids: and (4) an additional pathway manifesting as a long-term decline in winter phytoplankton biomass has been identified, but its genesis is uncertain. Overall, the Delta lost 43% in annual primary production during the period. Given the evidence for food limitation of primary Consumers, these findings provide a partial explanation for widespread Delta species declines over the past few decades. Turbid nutrient-rich systems Such as the Delta may he inherently more variable than other tidal systems because certain compensatory processes are absent. Comparisons among systems, however can be tenuous because conclusions about the magnitude and mechanisms of variability are dependent on length of data record.

Jin, L., W. M. Ju, et al. (2000). "Study on ann-based multi-step prediction model of short-term climatic variation." Advances in Atmospheric Sciences 17(1): 157-164.

In the context of 1905-1995 series from Nanjing and Hangzhou, study is undertaken of establishing a predictive model of annual mean temperature in 1996-2005 to come over the Changjiang (Yangtze River) delta region through mean generating function and artificial neural network in combination. Results show that the established model yields mean error of 0.45 degrees C for their absolute values of annual mean temperature from 10 yearly independent samples (1986-1995) and the difference between the mean predictions and related measurements is 0.156 degrees C. The developed model is found superior to a mean generating function regression model both in historical data fitting and independent sample prediction.

Justic, D., N. N. Rabalais, et al. (2002). "Modeling the impacts of decadal changes in riverine nutrient fluxes on coastal eutrophication near the Mississippi River Delta." Ecological Modelling 152(1): 33-46.

A mathematical model was used to link decadal changes in the Mississippi River nutrient flux to coastal eutrophication near the Mississippi River Delta. Model simulations suggest that bottom water hypoxia intensified about 30 years ago, as a probable consequence of increased net productivity and increased sedimentation of the organic material produced in situ in the upper water column. Model simulations also suggest that long-term increase in riverine nutrient fluxes has been responsible for this historical decrease in bottom layer oxygen concentrations. Importantly, model simulations are in good agreement with the available historical data from the northern Gulf of Mexico, and are additionally supported by the retrospective analyses of sedimentary records. Conclusively, this modeling study supports the hypothesis that riverine nutrient fluxes, via their influence on net productivity of the upper water column, play a major role in controlling the development of bottom water hypoxia and accumulation of organic carbon in coastal sediments. (C) 2002 Elsevier Science B.V. All rights reserved.

Justic, D., N. N. Rabalais, et al. (2003). "Simulated responses of the Gulf of Mexico hypoxia to variations in climate and anthropogenic nutrient loading." Journal of Marine Systems 42(3-4): 115-126.

A mathematical model was used to simulate monthly responses of the Gulf of Mexico hypoxia to variations in climate and anthropogenic nutrient loading over a 45-year period. We examined six hypothetical future scenarios that are based on observed and projected changes in the Mississippi River discharge, Mississippi River nitrate concentrations, and ambient water temperatures. In particular, we investigated the implications of a 30% decrease in the Mississippi River nitrogen flux, which was recently proposed by the Mississippi River Watershed/Gulf of Mexico Hypoxia Task Force as a measure to reduce the size of the hypoxic zone. Model simulations suggest that the frequency of hypoxia in the northern Gulf of Mexico is highly sensitive to variations in riverine nitrate flux, but also to variations in freshwater discharge and ambient water temperatures. A 30% decrease in the Mississippi River nitrate flux, for example, would reduce the frequency of hypoxia by 37%. Nevertheless, a 20% increase the Mississippi River discharge, which may occur under some climate change scenarios, would produce an increase in the frequency of hypoxia of the same magnitude. Thus, if the potential climatic variations are taken into account, a 30% decrease in the nitrogen flux of the Mississippi River may not be sufficient to accomplish the proposed hypoxia management goal. (C) 2003 Elsevier B.V. All rights reserved.

Khush, G. S. (1997). "Origin, dispersal, cultivation and variation of rice." Plant Molecular Biology 35(1-2): 25-34.

There are two cultivated and twenty-one wild species of genus Oryza O. sativa, the Asian cultivated rice is grown ail over the world. The African cultivated rice, O. glaberrima is grown on a small scale in West Africa. The genus Oryza probably originated about 130 million years ago in Gondwanaland and different species got distributed into different continents with the breakup of Gondwanaland. The cultivated species originated from a common ancestor with AA genome. Perennial and annual ancestors of O. sativa are O. rufipogon and O. nivara and those of O. glaberrima are O. longistaminata, O. breviligulata and O. glaberrima probably domesticated in Niger river delta. Varieties of O. sativa are classified into six groups on the basis of genetic affinity. Widely known indica rices correspond to group I and japonicas to group VI. The so called javanica rices also belong to group VI and are designated as tropical japonicas in contrast to temperate japonicas grown in temperate climate. Indica and japonica rices had a polyphyletic origin. Indicas were probably domesticated in the foothills of Himalayas in Eastern India and japonicas somewhere in South China. The indica rices dispersed throughout the tropics and subtropics from India. The japonica rices moved northward from South China and became the temperate ecotype. They also moved southward to Southeast Asia and from there to West Africa and Brazil and became tropical ecotype. Rice is now grown between 55 degrees N and 36 degrees S latitudes. It is grown under diverse growing conditions such as irrigated, rainfed lowland, rainfed upland and floodprone ecosystems. Human selection and adaptation to diverse environments has resulted in numerous cultivars. It is estimated that about 120000 varieties of rice exist in the world. After the establishment of International Rice Research Institute in 1960, rice varietal improvement was intensified and high yielding Varieties were developed. These varieties are now planted to 70% of world's riceland. Rice production doubled between 1966 and 1990 due to large scale adoption of these improved varieties. Rice production must increase by 60% by 2025 to feed the additional rice consumers. New tools of molecular and cellular biology such as anther culture, molecular marker aided selection and genetic engineering will play increasing role in rice improvement.

Kotera, A., E. Nawata, et al. (2004). "A model for phenological development of Vietnamese rice influenced by transplanting shock." Plant Production Science 7(1): 62-69.

Phasic development of rice is influenced by various climatic conditions and the nursery duration. As a step toward the analysis of yield potential and yield loss in the Red River Delta, Vietnam, we conducted field trials with different nursery durations and transplanting times to develop a model for estimating heading times of a non-photosensitive cultivar CR203 in the Red River Delta. Days from seedling emergence to heading varied from 73 to 106 d, the rainy season crops having a shorter duration than the winter-spring season crops. The heading time could generally be estimated by the function of air temperature, but the delay in heading due to transplanting (transplanting shock), defined as the difference in the days from emergence to heading between transplanted and direct-seeded rice, ranged from 1 to 9 d and caused a substantial error in the heading time estimation. This variation in the delay of heading was explained as a function of the seedling age at the transplanting time. The model considering the transplanting shock estimated the heading dates in the independent data sets obtained at fields of local farmers with root mean square deviation (RMSD) of 2.15, while the model not considering the transplanting shock estimated those with a RMSD of 3.34. We conclude that this simple transplanting shock model was applicable for estimating the rice phasic development in the Red River Delta.

Laing, T. E., K. M. Ruhland, et al. (1999). "Past environmental and climatic changes related to tree-line shifts inferred from fossil diatoms from a lake near the Lena River Delta, Siberia." Holocene 9(5): 547-557.

Changes in diatom assemblages in a sediment core taken from a tundra lake near the Lena River Delta, northeastern Siberia, reflect climatic and environmental changes throughout the Holocene. Significant limnological changes occurred at the same time as trees advanced into the region c. 9100 cal. yr BP (8500 radiocarbon yr BP) and subsequently retreated c. 3800 cal. yr BP (3500 radiocarbon yr BP). Prior to this treeline shift, diatom assemblages were dominated by small benthic Fragilaria species, and diatom-inferred alkalinity values were high, suggesting that climatic conditions were cool and relatively dry, and that lake productivity was probably low. Coincident with tree-line advance into the region c. 9100 cal. yr BP, inferred alkalinity decreased and remained low throughout the forested period, reflecting soil development and increased organic runoff associated with the shift in catchment vegetation. The establishment of a larch forest in the catchment corresponded with an initial period of limnological change between 9100 and 7700 cal. yr BP, suggesting that soil and forest development rook place over approximately 1400 years. Between c. 7700 cal. yr BP (c. 7000 radiocarbon yr BP) and 3800 cal. yr BP, a stable diatom assemblage dominated by Achnanthes species and low diatom-inferred alkalinity indicate the influence of organic runoff associated with a fully developed forest. A return to cooler conditions and reversion to shrub tundra c. 3800 cal. yr BP coincided with a shift back to a Fragilaria-dominated diatom assemblage and an increase in diatom-inferred alkalinity. Recent conditions have been marked by declining alkalinity estimates and a minor change in diatom assemblages, most likely reflecting an influx of humic substances from catchment pears. The close correlation between trends in reconstructed alkalinity and catchment vegetation suggests that diatom-inferred alkalinity may provide a sensitive record of soil and forest development, in unpolluted circumneutral or alkaline tree-line lakes.

Le Gal, P. Y. and F. Papy (1998). "Co-ordination processes in a collectively managed cropping system: Double cropping of irrigated rice in Senegal." Agricultural Systems 57(2): 135-159.

Collective management of cropping systems is common in tropical countries when one production factor (e.g. machinery or an irrigated scheme) is shared by a number of farmers. To achieve their technical objectives in these contexts, farmers have to co-ordinate decision-making processes among themselves and with their economic partners. A 3-year study was carried out on two irrigated schemes in the Senegal river delta, its aim was to understand (1) the problems farmers' organizations managing schemes faced when carrying out annual double cropping of rice and (2) how they managed to co-ordinate the different actors (individual farmers, contractors and collective organizations) interacting on these schemes. The results presented here relate mainly to the harvest part of the problem. They show double cropping success varies from one site to another and from one year to another, depending on different starting dates and global harvest performances. The comprehensive model proposed to explain this diversity includes (1) analysing individual farmers' and contractors' decision-making processes indicating the uncertainty of their behaviour and its effects on plot conditions (maturity and trafficability) and machiner), performances and (2) classifying collective co-ordination processes under three main strategies of contractualizing relations with local contractors by granting harvest monopolies, simplifying complex decisions such as choosing a harvest starting date at scheme level and adjusting to unforseen Events during task operation, mainly by looking for extra combine harvesters. The efficiency of these strategies is analysed in relation to the structural characteristics of the two schemes. In our discussion we propose a general framework to explain the co-ordination problems met by farmers in this context including lack of experience, diversity of individual behaviour and uncertainty. Some suggestions are put forward to improve and accelerate the organizational learning processes already acquired by farmers, in terms of technical references, scheme design and modelling. (C) 1998 Elsevier Science Ltd. All rights reserved.

Leconte, R., A. Pietroniro, et al. (2001). "Effects of flow regulation on hydrologic patterns of a large, inland delta." Regulated Rivers-Research & Management 17(1): 51-65.

The Peace-Athabasca River Delta (PAD) is one of the largest freshwater deltas and most biologically productive in the world. Because regional evaporation is greater than precipitation, the thousands of lakes and wetlands dotting this area rely on periodic flooding from the Peace and Athabasca rivers to be replenished. Flood frequency significantly declined beginning in the mid-1970s, several years after the initiation of flow regulation of the Peace River. However, the drying trend was interrupted in 1996 when the PAD experienced extensive inland inundation on two separate occasions, one in the spring and one in the summer. A one-dimensional numerical hydrodynamic model was used to evaluate the role of flow regulation and hydroclimatic conditions on the water levels of major lakes found in the PAD. Three Peace River flow scenarios were analysed: the observed flows, the flow regime without the 'precautionary drawdown' spill which was required because of the discovery of a sinkhole at the crest of the dam, and the naturalized flow regime, which assumed no dam regulation. Modelling results indicated that the effect of the spill on the flow regime within the PAD was approximately equivalent in magnitude, although different in timing, to what would have resulted from the prevailing hydroclimatic conditions in an unregulated system. Furthermore, even in the absence of the precautionary drawdown spill, the lake levels would have risen well above the maximum daily average, suggesting that 1996 was one of the wettest years on record. Finally, the hydrodynamic regime observed at the end of the summer 1996 was very similar to that modelled under unregulated flow conditions, suggesting that flow regulation could be used to alter the hydrodynamic regime of a large delta to at least partially restore natural conditions and potentially improve ecosystem health. Copyright (C) 2001 John Wiley & Sons, Ltd.

Lemons, D. R., M. R. Milligan, et al. (1996). "Paleoclimatic implications of late Pleistocene sediment yield rates for the Bonneville Basin, northern Utah." Palaeogeography Palaeoclimatology Palaeoecology 123(1-4): 147-159.

Climate factors such as precipitation and temperature as well as climate-driven geomorphic processes such as glaciation affect rates of erosion and the amount of sediment supplied from a drainage basin (sediment yield). Thus, sediment yield rates provide paleoclimatic implications, although very little work has been published on ancient sediment yield rates. Late Pleistocene Lake Bonneville (Utah, Idaho and Nevada), with its well-documented lake level history and well-preserved deltaic sequences, provides a unique opportunity to estimate ancient sediment yield rates. Two end-member delta systems, coarse-grained (gravel) classic Gilbert-type deltas and fine-grained (sand, silt and clay) deltas, are exposed along the eastern margin of paleolake Bonneville. One example of each end-member delta is examined in this study (American Fork and Weber River deltas). The established Bonneville hydrograph can be used to determine time of deposition for a given package of sediments because these shoreline deltaic sediments were deposited in shallow water. The geomorphic expressions of these deltas are well-preserved and their sediment volumes can be determined. River drainage basin area can be combined with time constraints and delta volumes to estimate sediment yield rates. Sediment yield rate estimates for the coarse-grained American Fork and fine-grained Weber River deltas are 478 m(3) km(-2) yr(-1) +/-34% and 705 m(3) km(-2) yr(-1) +/-15%, respectively. The similarity of these values is somewhat surprising due to the large difference in drainage basin sizes (American Fork approximate to 160 km(2) and Weber River approximate to 3328 km(2)). However, this similarity suggests that precipitation may be the dominant control on sediment yield. Using sediment yield/precipitation regression equations developed for similar modern basins in the Southern Alps of New Zealand, a first-order approximation of paleoprecipitation is 1.6 m/yr (+/-14% for American Fork delta) and 1.9 m/yr (+/-7% for Weber River delta). These paleoprecipitation value are comparable to modern precipitation values of 0.4-1.5 m/yr (range of mean values over both drainage basins). A maximum late Pleistocene precipitation increase of 33% over the modern day value is suggested. This is determined by the difference between the highest paleoprecipitation rate (1.9 m/yr+7% of the Weber River delta) and the modern value (1.5 m/yr). Previous climate models and this 33% paleoprecipitation increase, suggest a maximum decrease in basin floor paleotemperature of approximately 13 degrees C. This paleotemperature decrease is consistent with previous estimates of late Pleistocene temperatures (using amino acid epimerization rates and periglacial wedges) in the Bonneville Basin and adjacent areas. These estimates suggest that although late Pleistocene precipitation rates may have been slightly higher than present (up to 33% higher), late Pleistocene temperature and evaporation rates were more important in the development of Lake Bonneville and associated glaciers.

Li, C. C., J. T. Mao, et al. (2003). "Characteristics of distribution and seasonal variation of aerosol optical depth in eastern China with MODIS products." Chinese Science Bulletin 48(22): 2488-2495.

The accuracy of MODIS aerosol products from the NASA Terra Satellite is validated in comparison with the results of sun-photometer observations in Beijing and Hong Kong. By analyzing the MODIS aerosol products within the period of August 2000 to April 2003, it is believed that human activities are the main source of aerosols in the eastern part of China. This is based on the facts that all areas with relatively high values are consistent with regions of dense population and fast economic development, such as the North China Plain, the Sichuan Basin and the Pearl River Delta. It is also supported by the distribution of Angstromngstrom exponents showing that most aerosols in the eastern part of China are closely related to human activities, excepting the strong sandstorm episodes occurring in spring, fall and winter. In contrast to developed countries, the Angstromngstrom exponent of urban area in China is lower than its surroundings, indicating that the contribution of local floating dust and soot attributed to human activities is significant. Results presented in this paper provide important data for further research on climatic change and environmental study.

Liu, J. P., J. D. Milliman, et al. (2002). "The Shandong mud wedge and post-glacial sediment accumulation in the Yellow Sea." Geo-Marine Letters 21(4): 212-218.

Two well-defined deltaic sequences in the Bohai Sea and in the South Yellow Sea represent post-glacial accumulation of Yellow River-derived sediments. Another prominent depocenter on this epicontinental shelf, a pronounced clinoform in the North Yellow Sea, wraps around the northeastern and southeastern end of the Shandong Peninsula, extending into the South Yellow Sea. This Shandong mud wedge is 20 to 40 m thick and contains an estimated 300 km(3) of sediment. Radiocarbon dating, shallow seismic profiles, and regional sea-level history suggest that the mud wedge formed when the rate of post-glacial sea-level rise slackened and the summer monsoon intensified, at about 11 ka. Geomorphic configuration and mineralogical data indicate that present-day sediment deposited on the Shandong mud wedge comes not only from the Yellow River but also from coastal erosion and local rivers. Basin-wide circulation in the North Yellow Sea may transport and redistribute fine sediments into and out of the mud wedge.

Liu, J. Y., M. L. Liu, et al. (2003). "Study on spatial pattern of land-use change in China during 1995-2000." Science in China Series D-Earth Sciences 46(4): 373-+

It is more and more acknowledged that land-use/cover dynamic change has become a key subject urgently to be dealt with in the study of global environmental change. Supported by the Landsat TM digital images, spatial patterns and temporal variation of land-use change during 1995 -2000 are studied in the paper. According to the land-use dynamic degree model, supported by the 1km GRID data of land-use change and the comprehensive characters of physical, economic and social features, a dynamic regionalization of land-use change is designed to disclose the spatial pattern of land-use change processes. Generally speaking, in the traditional agricultural zones, e.g., Huang-Huai-Hai Plains, Yangtze River Delta and Sichuan Basin, the built-up and residential areas occupy a great proportion of arable land, and in the interlock area of farming and pasturing of northern China and the oases agricultural zones, the reclamation I of arable land is conspicuously driven by changes of production conditions, economic benefits and climatic conditions. The implementation of "returning arable land into woodland or grassland" policies has won initial success in some areas, but it is too early to say that the trend of deforestation has been effectively reversed across China. In this paper, the division of dynamic regionalization of land-use change is designed, for the sake of revealing the temporal and spatial features of land-use change and laying the foundation for the study of regional scale land-use changes. Moreover, an integrated study, including studies of spatial pattern and temporal process of land-use change, is carried out in this paper, which is an interesting try on the comparative studies of spatial pattern on change process and the change process of spatial pattern of land-use change.

McGowan, H. A. and A. P. Sturman (1997). "Characteristics of aeolian grain transport over a fluvio-glacial lacustrine braid delta, Lake Tekapo, New Zealand." Earth Surface Processes and Landforms 22(8): 773-784.

This paper presents results from one of the few scientific studies to examine the physical characteristics of aeolian sediment transport in an alpine area, where topographically reinforced foehn winds initiate dust storm events. The major objective of this study is to improve knowledge of aeolian processes in mid-latitude alpine regions experiencing extreme wind speeds. Of particular interest is the role of surface characteristics in contributing to the unusually deep saltation layer which is seen to form over fluvio-glacial deposits in the Southern Alps of New Zealand. Sediment was collected at several heights.(0.5, 1, 2 and 4m) and locations over a large alpine braided river delta, and standard laboratory techniques used to examine grain size characteristics. An image processing technique was also used to evaluate grain roundness. Grains filtered from the airstream at 0.5m and Im above such surfaces were found to display a mean grain size of approximately 300 to 435 mu m, resembling grain size characteristics of saltation clouds previously observed in high latitude, cold climate locations, in contrast to desert and prairie environments. Samples collected at 2 and 4m above the surface were found to consist of 60 to 65 per cent sand-sized material, with some grains exceeding 1-1.5mm in diameter. Grain shape analysis conducted on silt-and clay-sized grains filtered from the airstream above mixed sand and gravel surfaces showed such grains to display an increase in grain roundness with height. This characteristic is thought to reflect the airstream's shape-sorting ability and has important implications with respect to the often observed increase in,grain roundness in aeolian deposits with increasing distance from source areas. Namely, if more rounded grains are preferentially carried higher into the airstream and therefore into regions of higher wind speed, they should theoretically be transported further from the entrainment zone before being deposited. The high wind speeds observed, often exceeding 30ms(-1), are seen to transport significantly larger sediment than reported in the literature for desert and prairie environments. In addition, the mixture of grain sizes, and especially the pebble-and cobble-sized clasts that dominate the fluvio-glacial deposits associated with the braided rivers in this mountain region, also appear to increase significantly the trajectory height of saltating sand grains. As a result of these two factors, the depth of the saltation cloud often exceeds Im. Observations made in this study therefore highlight the need for field and laboratory aeolian process studies to be extended to examine grain transport over coarse-grained beds during much higher wind velocities than typically reported in the literature. Such studies would provide a valuable insight into aeolian processes in high latitude/altitude environments, such as loess genesis. (C) 1997 by John Wiley & Sons, Ltd.

Medus, J. and C. Parron (2000). "A slow environmental transition derived from changes in sedimentology and pollen assemblages in the Senegal River Delta about 6000 yrs BP." Archives Des Sciences 53(3): 169-176.

Palynological and mineralogical data from sections located in the N'Diael region, (Senegal River Delta) and exhibiting a peaty lever overlain by reddish sands, are presented. First they give the opportunity to confirm the radiocarbon dated sedimentological transition of peat mangrove facies to elastic continental beds at ca. 6600-6400 yrs BP. Secondly, because the pollen assemblage of the sandy sediments overlying the mangrove peat level is characterized by a high percentage of Poaceae and the absence of marine palynomorphs a dry, continental environment appears to have replaced the coastal tidal lagoon one; moreover, the clay mineral association of sandy levels points to a elastic origin by reworking of the surrounding ferralitic cover. The overall data allow to conclude to the gradual setting in of continental conditions and aridification of the studied area that seems to have begun soon after 6400 yrs BP and have reached a maximum ca. 5000 yrs BP.

Meldahl, K. H. (1995). "Pleistocene Shoreline Ridges from Tide-Dominated and Wave-Dominated Coasts - Northern Gulf of California and Western Baja-California, Mexico." Marine Geology 123(1-2): 61-72.

The arid climate of northwestern Mexico preserves Pleistocene beach deposits forming linear, shoreline-parallel ridges on the coastal plains of Sonora, northern Gulf of California, and the Vizcaino Peninsula of Baja California. Beach deposits represent both cheniers (northern Gulf) and beach ridges (Vizcaino Peninsula). They formed during Pleistocene sea-level highstands, most commonly during oxygen-isotope stage 5e (similar to 125 ka). The ridges are 0.5 to 5.0 m thick, < 10 to > 100 m wide, and < 100 to > 1000 m long, coarse-grained with common low- to high-angle cross stratification, and are dominated by bivalve shells. Ridges from the tide-dominated northern Gulf of California and the wave-dominated western Vizcaino Peninsula differ in underlying lithology, size, profile, and shell fragmentation. Northern Gulf ridges progradationally overlie deltaic or marsh deposits, are smaller (median thickness 1.4 m; median width 25 m; median length 300 m), typically have a seaward-dipping upper surface and a linear crest on the landward side, and have low levels of fragmentation of large bivalve shells. In contrast, Vizcaino ridges disconformably overlie bedrock on wave-cut terraces, are larger (median thickness 3.3 m; median width 100 m; median length 2000 m), typically have a landward-dipping upper surface and a linear crest on the seaward side, and contain beds of extensively fragmented large bivalve shells. These differences are interpreted to reflect contrasting processes of ridge formation in the two regions. The ridges of the tide-dominated northern Gulf are true cheniers-transgressive beach deposits produced during episodes of elastic starvation associated with shifts in Colorado River delta deposition. They are modified primarily through episodic washover processes during high tides and storms. The ridges of the wave-dominated Vizcaino Peninsula are regressive beach ridges developed on highstand wave-cut terraces. They are modified primarily through continuous wave accretion to the beach face, and secondarily by washover processes.

Mutti, E., R. Tinterri, et al. (2003). "Deltaic, mixed and turbidite sedimentation of ancient foreland basins." Marine and Petroleum Geology 20(6-8): 733-755.

The marine fill of ancient foreland basins is primarily recorded by depositional systems consisting of facies and facies associations deposited by a variety of sediment gravity flows in shallow-marine, slope and basinal settings. Tectonism and climate were apparently the main factors controlling the sediment supply, accommodation and depositional style of these systems. In marginal deltaic systems, sedimentation is dominated by flood-generated hyperpycnal flows that build up impressive accumulations of graded sandstone beds in front of relatively small high-gradient fan-deltas and river deltas. During periods of tectonically forced lowstands of sealevel, these systems may commonly shift basinward to shelfal and slope regions. Instability along the edges of these lowstand deltas and sand-laden hyperpycnal flows generate immature and coarse-grained turbidite systems commonly confined within structural depressions and generally encased in distal delta-front and prodeltaic deposits. Because of the close vertical and lateral stratigraphic relations between deltaic and turbidite-like facies, these marginal systems are herein termed 'mixed depositional systems'. They are very common in the fill of foreland basins and represent the natural link between deltaic and basinal turbidite sedimentation. Basinal turbidite systems form in deeper water elongate highly subsiding troughs (foredeeps) that developed in front of advancing thrust systems. The impressive volumes of sheet-sandstones that form the fill of these troughs suggest that basinal turbidite systems are likely to form following periods of dramatic tectonic uplift of adjacent orogenic wedges and related high-amplitude tectonically-forced sealevel lowstands. In such deep basinal settings, sediment flux to the sea is dramatically increased by newly formed sediment in fluvial drainage basins and the subaefial and submarine erosion of falling-sealevel deltaic deposits generated during the uplift. Turbidity currents are very likely to be mainly triggered by floods, via hyperpycnal flows and related sediment failures, but can fully develop only in large-scale erosional conduits after a phase of catastrophic acceleration and ensuing bulking produced by bed erosion. This process leads to deepening and widening of the conduits and the formation of large-volume highly efficient bipartite currents whose energy dissipation is substantially reduced by the narrow and elongate basin geometry. These currents can thus carry their sediment load over considerable distances down the basin axis. (C) 2003 Elsevier Ltd. All fights reserved.

Pont, D., J. W. Day, et al. (2002). "Response scenarios for the deltaic plain of the Rhone in the face of an acceleration in the rate of sea-level rise with special attention to Salicornia-type environments." Estuaries 25(3): 337-358.

One of the most critical problems facing many deltaic wetlands is a high rate of relative sea-level rise due to a combination of eustatic sea-level rise and local subsidence. Within the Rhone delta, the main source of mineral input to soil formation is from die river, due to the low tidal range and the presence of a continuous sea wall. We carried out field and modeling studies to assess the present environmental status and future conditions of the more stressed sites, i.e., Salicornia-type marshes with a shallow, hypersaline groundwater. The impacts of management practices are considered by comparing impounded areas with riverine areas connected to the Rhone River. Analysis of vegetation transects showed differences between mean soil elevation of Arthrocnemum fruticosum (+31.2 cm), Arthrocnemum glaucum (+26.5 cm), bare soil (+16.2 cm), and permanently flooded soil (-12.4 cm). Aboveground and belowground production showed that root:shoot ratio for A. fruticosum and A. glaucum was 2.9 and 1.1, respectively, indicating more stressful environmental conditions for A. glaucum with a higher soil salinity and lack of soil drainage. The annual leaf litter production rate of the two species is 30 times higher than annual stem litter production, but with a higher long-term decomposition rate associated with leaves. We developed a wetland elevation model designed to predict the effect of increasing rates of sea-level rise on wetland elevation and Salicornia production. The model takes into account feedback mechanisms between soil elevation and river mineral input, and primary production. In marshes still connected to the river, mineral input decreased quickly when elevation was over 21 cm. Under current sea-level rise conditions, the annual amount of riverine mineral input needed to maintain the elevation of the study marshes is between 3,000 and 5,000 g m(-2) yr(-1). Simulations showed that under the Intergovernmental Panel on Climate Change best estimate sea-level rise scenario, a mineral input of 6,040 g m(-2) yr(-1) is needed to maintain marsh elevation. The medium term response capacity of the Rhone deltaic plain with rising sea level depends mainly on the possibility of supplying sediment from the river to the delta, even though the Rhone Delta front is wave dominated. Within coastal impounded marshes, isolated from the river, the sediment supply is very low (10 to 50 g m(-2) yr(-1)), and an increase of sea-level rise would increase the flooding duration and dramatically reduce vegetation biomass. New wetland management options involving river input are discussed for a long-term sustainability of low coastal Mediterranean wetlands.

Prowse, T. D. and V. Lalonde (1996). "Open-water and ice-jam flooding of a northern Delta." Nordic Hydrology 27(1-2): 85-100.

Flooding is critical to the ecosystem health of many river-delta environments, particularly to perched-ponds and lakes that are vertically separated from the open-water flow system. This is the case for the Peace-Athabasca Delta in northern Canada, one of the world's largest, freshwater deltas. Unfortunately, this delta has not experienced a major flood since 1974. As a result, significant drying has occurred in the higher-elevation portions of the Delta landscape. This has led to significant changes in, for example, the vegetation regime and the related small-mammal habitat. For almost two decades, popular belief was that drying of the Delta was due to a reduction in the size of open-water floods resulting from upstream flow regulation and/or changes in climate. Following a historically high flood in 1990, however, it was realized that open-water floods were relatively ineffective in flooding the perched bases. A historical analysis of hydrometric records revealed that the major peak-water levels have been produced at the time of break-up. The spring flow driving such events are more related to downstream tributary runoff than flow produced within the headwaters, above the point of regulation. Other ice factors, however, such as thickness, strength, and winter levels, may also have been important in controlling break-up severity.

Pruszak, Z., M. Szmytkiewicz, et al. (2002). "Coastal processes in the Red River Delta area, Vietnam." Coastal Engineering Journal 44(2): 97-126.

The economy and life in Vietnam is associated with the existence and development of large river deltas, i.e. the Mekong Delta and the Red River Delta. The latter is located in the northern part of Vietnam and apart from thousands of square kilometers of the area, it includes more than 165 km of coastline as well. In this area, the seashore and the adjacent densely populated, low-lying regions are often subject to intense impacts from the river (floods) and the sea (typhoons, changes in sea level, currents, etc.) and therefore undergo substantial and dynamic changes and destructions. In the current study, one of the coastal segments that are most vulnerable to destruction in Vietnam is analyzed. A synthetic analysis of the available information was carried out first and then the modeling of wave climate, currents and sediment movement patterns in the nearshore zone was done. The formulation of a phenomenological model of sediment budget, adequate for the amount of available information, allowed for assessment of the existing sediment fluxes and their relations to morphodynamic processes taking place in the studied area.

Rabalais, N. N., R. E. Turner, et al. (2001). "Hypoxia in the Gulf of Mexico." Journal of Environmental Quality 30(2): 320-329.

Seasonally severe and persistent hyporia, or low dissolved oxygen concentration, occurs on the inner- to mid-Louisiana continental shelf to the west of the Mississippi River and Atchafalaya River deltas. The estimated areal extent of bottom dissolved oxygen concentration less than 2 mg L-1 during mid-summer surveys of 1993-2000 reached as high as 16 000 to 20 000 km(2). The distribution for a similar mapping grid for 1985 to 1992 averaged 8000 to 9000 km(2). Hypoxia occurs below the pycnocline from as early as late February through early October, but is most widespread, persistent, and severe in June, July, and August. Spatial and temporal variability in the distribution of hypoxia exists and is, at least partially, related to the amplitude and phasing of the Mississippi and Atchafalaya discharges and their nutrient flux. Mississippi River nutrient concentrations and loadings to the adjacent continental shelf have changed dramatically this century, with an acceleration of these changes since the 1950s to 1960s. An analysis of diatoms, foraminiferans, and carbon ac accumulation in the sedimentary record provides evidence of increased eutrophication and hypoxia in the Mississippi River delta bight coincident with changes in nitrogen loading.

Reyes, E., M. L. White, et al. (2000). "Landscape modeling of coastal habitat change in the Mississippi delta." Ecology 81(8): 2331-2349.

A landscape model was developed to investigate and predict the environmental factors affecting wetland habitat change within the Barataria and Terrebonne basins of coastal Louisiana, USA. The model linked an overland-flooding hydrodynamic module, using cells of 100 km(2) in size and operating at a 1-h time step, and a spatially articulated ecosystem module, resolving habitat type and change for 1-km(2) cells in daily time steps. Integration across different temporal and spatial scales was accomplished with interpolation routines and averaging algorithms. Forcing functions included dominant regional processes, such as subsidence, sedimentation, and sea-level rise. Hydrologic functions were calibrated against existing climate and hydrologic time series, while habitat information was compared to maps prepared by the United States Fish and Wildlife Service (USFWS) for 1978 and 1988. Spatial calibration was done by initializing the landscape pattern of the model to a 1978 USFWS habitat map. After a 10-yr simulation, the results were compared against a 1988 USFWS habitat map. Simulated maps had an accuracy of 85-90 (out of a maximum of 100), based on a multiple resolution fit algorithm. For validation the model was initialized with a 1956 USFWS habitat map, and the results from a 32-yr simulation were compared to the 1988 USFWS habitat map. The landscape model produced reasonable regional agreement, despite the fact that small-scale processes and features were not included. The validation runs produced land-loss rates that matched historical trends with an accuracy fit above 75. The model simulated 30 years into the future, starting in 1988, testing for long-term climate variability under diverse scenarios. Results indicated that weather variability impacts land-loss rates more than replication of extreme weather years. Even when extreme dry and wet years were repeated, the model predicted lower land loss when compared to historical records. This is indicative of the ability of the simulated plant communities to adapt to repetitive climatic forcing functions.

Romashkin, P. A. and D. F. Williams (1997). "Sedimentation history of the Selenga Delta, Lake Baikal: Simulation and interpretation." Journal of Paleolimnology 18(2): 179-186.

The computer simulation of a Lake Baikal seismic profile located in the Selenga River Delta area resulted in a lake level record of the last 600 kyr. This curve demonstrates several low-magnitude episodes and both a dramatic 300 m fall and a more than 150 m increase of the lake level relative to present situation. The greatest change in paleo-lake depth at 300 ka corresponds in time with the major glaciation in the Eastern Siberia and is probably the response of the lake to this climatic phenomenon. The results of this study conform with existing hypotheses on the regional tectonic history and climatic events.

Rybczyk, J. M. and D. R. Cahoon (2002). "Estimating the potential for submergence for two wetlands in the Mississippi River Delta." Estuaries 25(5): 985-998.

We used a combined field and modeling approach to estimate the potential for submergence for one rapidly deteriorating (Bayou Chitigue Marsh) and one apparently stable (Old Oyster Bayou Marsh) saltmarsh wetland in coastal Louisiana, given two eustatic sea level rise scenarios: the current rate (0.15 cm year(-1)); and the central value predicted by the Intergovernmental Panel on Climate Change (48 cm. by the year 2100). We also used the model to determine what processes were most critical for maintaining and influencing salt marsh elevation including, mineral matter deposition, organic matter production, shallow subsidence (organic matter decomposition + primary sediment compaction), deep subsidence, and sediment pulsing events (e.g., hurricanes). Eight years of field measurements from feldspar marker horizons and surface elevation tables revealed that the rates of vertical accretion at the Bayou Chitigue Marsh were high (2.26 (0.09) cm yr(-1) (mean +/- SE)) because the marsh exists at the lower end of the tidal range. The rate of shallow subsidence was also high (2.04 (0.1) cm yr(-1)), resulting in little net elevation gain (0.22 (0.06) cm yr(-1)). In contrast, vertical accretion at the Old Oyster Bayou Marsh, which is 10 cm higher in elevation, was 0.48 (0.09) cm yr(-1). However, there was a net elevation gain of 0.36 (0.08) cm yr(-1) because there was no significant shallow subsidence. When these rates of elevation gain were compared to rates of relative sea level rise (deep subsidence plus eustatic sea level rise), both sites showed a net elevation deficit although the Bayou Chitigue site was subsiding at approximately twice the rate of the Old Oyster Bayou site (1.1 cm yr(-1) versus 0.49 cm yr(-1) respectively). These field data were used to modify, initialize, and calibrate a previously published wetland soil development model that simulates primary production and mineral matter deposition as feedback functions of elevation. Sensitivity analyses revealed that wetland elevation was most sensitive to changes in the rates of deep subsidence, a model forcing function that is difficult to measure in the field and for which estimates in the literature vary widely. The model also revealed that, given both the current rate of sea level rise and the central value estimate, surface elevation at both sites would fall below mean sea level over the next 100 years. Although these results were in agreement with the field study, they contradicted long term observations that the Old Oyster Bayou site has been in equilibrium with sea level for at least the past 50 years. Further simulations showed that the elevation at the Old Oyster Bayou site could keep pace with current rates of sea level rise if either a lower rate for deep subsidence was used as a forcing function, or if a periodic sediment pulsing function (e.g., from hurricanes) was programmed into the model.

Saleh, A. A., K. A. Zeller, et al. (2003). "Amplified fragment length polymorphism diversity in Cephalosporium maydis from Egypt." Phytopathology 93(7): 853-859.

Cephalosporium maydis. the causal agent of late wilt of maize, was first described in Egypt in the 1960s, where it can cause yield losses of up to 40% in susceptible plantings. We characterized 866 isolates of C. maydis collected from 14 governates in Egypt, 7 in the Nile River Delta and 7 in southern (Middle and Upper) Egypt, with amplified fragment length polymorphism (AFLP) markers. The four AFLP primer-pair combinations generated 68 bands, 25 of which were polymorphic, resulting in 52 clonal haplotypes that clustered the 866 isolates into four phylogenetic lineages. Three lineages were found in both the Nile River Delta and southern Egypt. Lineage IV, the most diverse group (20 haplotypes), was recovered only from governates in the Nile River Delta. In some locations, one lineage dominated (up to 98% of the isolates recovered) and, from some fields, only a single haplotype was recovered. Under field conditions in Egypt, there is no evidence that C. maydis reproduces sexually. The nonuniform geographic distribution of the pathogen lineages within the country could be due to differences in climate or in the farming system, because host material differs in susceptibility and C. maydis lineages differ in pathogenicity.

Scavia, D., D. Justic, et al. (2004). "Reducing hypoxia in the Gulf of Mexico: Advice from three models." Estuaries 27(3): 419-425.

Summer hypoxia in the bottom waters of the northern Gulf of Mexico has received considerable scientific and policy attention because of potential ecological and economic impacts from this very large zone of low oxygen and because of the implications for management within the massive Mississippi River watershed. An assessment of its causes and consequences concluded that the almost 3-fold increase in nitrogen load to the Gulf is the primary external driver stimulating the increase in hypoxia since the middle of the last century. Results from three very different models are compared to reach the consensus that large-scale hypoxia likely did not start in the Gulf of Mexico until the mid-1970s and that the 30% nitrogen load reduction called for in an Action Plan to reduce hypoxia, agreed to by a federal, state, and tribal task force, may not be sufficient to reach the plan's goal. Caution is also raised for setting resource management goals without considering the long-term consequences of climate variability and change.

Searcy, C., K. Dean, et al. (1996). "A river-coastal sea ice interaction model: Mackenzie River Delta." Journal of Geophysical Research-Oceans 101(C4): 8885-8894.

It has been observed that arctic coastal regions which receive river discharge show significant ice regression in advance of other coastal areas without this source of sensible heat. This phenomena has been particularly apparent on satellite imagery. The work reported here attempts (1) to quantify and assess the influence of springtime river discharge on the removal of nearshore ice and (2) to demonstrate the utility of satellite imagery as a source of, data to ''drive'' a model assessing the influence of springtime river discharge on the removal of nearshore ice. Central to this work is a sequence of advanced very high resolution radiometer images of the Mackenzie Delta region, Northwest Territories, Canada. These images constitute a database establishing the temporal sequence of observable breakup events from which a thermodynamic model for the ice decay can bi: parameterized. The emphases of this model is the influence of the riverine sensible heat on the melting of sea ice and the ability of satellite imagery to monitor this process. For simplicity, climatological values rather than meteorological values for atmospheric and solar influences have been used. The results suggest that the river discharge supplies a significant amount of sensible heat to the base of the nearshore ice, accounting for nearly half of the energy required to melt the ice cover. As a result the coastal ice is removed 7-14 days in advance of areas without significant river discharge.

Somoza, L., A. Barnolas, et al. (1998). "Architectural stacking patterns of the Ebro delta controlled by Holocene high-frequency eustatic fluctuations, delta-lobe switching and subsidence processes." Sedimentary Geology 117(1-2): 11-32.

During the Late Pleistocene and Holocene (125 ka B.P. to present) a Type 1, 4th-order, depositional sequence, comprising regressive, lowstand, transgressive and highstand system tracts, formed worldwide. The Holocene (10 ka B.P. to present) part of this contains the latest and present highstand systems tract (HST). Within this and the underlying transgressive systems tract (TST) of the Ebro delta, in northeastern Spain, higher-frequency, 5th- to 6th-order, sea-level fluctuations are recognised. These form retrogradational and progradational high-frequency depositional sequence sets within the TST and HST, respectively. Each high-frequency sequence comprises: (1) a basal, highly reflective, shell lag, associated with an erosional (transgressive) surface; (2) aggradational deposits which seawards consist of a wedge of marine clays with transparent seismic facies, but inland are represented by thick peats; (3) progradational deposits: composed of sandy delta-front facies, displaying slope clinoforms; these pass seawards into prodeltaic grey silts, and landwards, into red silts and pebbly sands of delta-plain facies. The progradational deposits downlap towards their bases. The aggradational deposits formed in response to a period of rising sea-level and a rapid increase in accommodation space. Progradation began when sediment supply to the delta exceeded accommodation space as a result of relative sea-level fall. The relative sea-level curve for the delta has a stepped character, caused by the punctuation of the 4th-order sea-level trend by higher-frequency eustatic fluctuations as well as by high subsidence rates, of about 1.75 mm per year. The TST comprises retrogradational parasequences that onlap the underlying Pleistocene gravels. The maximum flooding surface separating the TST from the HST, was formed about 6900 yrs B.P. on the basis of C-14 dating of peats. The HST comprises progradational deltaic and aggradational units, stacked as progradational high-frequency parasequence sets. The HST of the Ebro delta is compared with other deltaic sequences around the world, in particular with that of the Mississippi delta. A tentative chronology of the high-frequency climatic and eustatic oscillations influencing deltaic sedimentation globally over the last 7000 years is presented. (C) 1998 Elsevier Science B.V. All rights reserved.

Staub, J. R., H. L. Among, et al. (2000). "Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia." Sedimentary Geology 133(3-4): 249-264.

The Holocene Rajang River delta plain, which covers an area of 6500 km(2), has developed in a tropical, ever-wet climatic setting. Feat deposits, up to 15 m thick, occur in this delta plain. The tributary system to the delta is about 50,000 km2 in area. Elevations exceed 2000 m in the drainage basin and hill slopes are steep. Rainfall in the region exceeds 370 cm/year, with highest rainfall levels or the "wet" season being coincident with the December-March monsoon. The monthly drainage-basin discharge is calculated to average about 3600 m(3)/s, and the discharge normally ranges from 1000 to 6000 m(3)/s. Spring tides in coastal areas range from 2.9 to 5.8 m. Tide data indicate that the tides are semidiurnal with a noticeable diurnal inequality. Vibracores recovered from bar forms in tidally influenced distributary channels contain laminated silts and sand-silt couplets that show evidence of rhythmic heterolithic stratification. Grain-size data indicate that these preserved delta plain siliciclastic sediments are the result of estuarine depositional processes that occur during intervals of reduced rainfall or the "dry" season (April-November). The number of laminae preserved per neap-spring cycle is the highest (congruent to 18-20), and the average thickness is the greatest in the middle part of the delta plain. Distributary channels in this region normally contain low-salinity brackish water to freshwater. Vibracores recovered from delta front and prodelta sediments show evidence of heterolithic stratification, but rhythmicity is absent. Grain-size data indicate that preserved delta front and prodelta sediments are implaced by " wet" season processes (December-March) when fluvial flux and delta-plain erosion are at their maxima. Individual silt laminae and/or silt and sand interbeds are sometimes many centimeters thick, but average about 1 cm. These silt laminae and silt and sand interbeds or varves represent annual sedimentation events. These varves demonstrate that about 24 million MT of sediment produced by the drainage basin is deposited in the delta front and prodelta region annually. (C) 2000 Elsevier Science B.V. All rights reserved.

Stone, G. W. and R. A. McBride (1998). "Louisiana barrier islands and their importance in wetland protection: Forecasting shoreline change and subsequent response of wave climate." Journal of Coastal Research 14(3): 900-915.

The role that barrier islands play in mitigating the wave climate in lower energy, bay or lagoonal environments has not yet been addressed in detail. With the exception of one study in which a shallow water wave prediction model (HISWA) (LIST et. al., 1992) was applied to idealized barrier-bay configurations, the critical linkages among barriers, wave energy transmission into bays, regenerated local waves, and subsequent wave climate have not been made. In Louisiana, barrier disintegration is rapid over the short-term (10(2) years) and the mere potential for impacts of barrier loss on the bay wave climate is highly significant. Because of a paucity in scientific data which could be utilized to address this issue, there remains a significant debate as to the value of barrier islands in mitigating wave climate in the bays and along fringing marshes. In this paper we present historical shoreline change data which are used to predict the rapid disintegration of a section of barrier island coast along central Louisiana (Isles Dernieres) and resultant forecasted increases in wave energy in the adjacent bays. The methods associated with shoreline, bathymetric and wave energy forecasting are briefly presented as an example of a larger, ongoing project regarding the feasibility of large-scale barrier island restoration in Louisiana. A brief overview of the magnitude and causal mechanisms associated with wetland loss are provided in addition to the implications associated with barrier island loss and subsequent detrimental impacts on fringing marshes. The example data set presented here indicates that the role of Louisiana's barrier islands comprising the Isles Dernieres in mitigating the wave climate in their adjacent bays and fringing marshes appears critical. Considering only fairweather conditions, the data indicate that the bays adjacent to the Isles Dernieres could experience an increase in wave height of 700% if the barrier chain is reduced to shoals. Although large-scale barrier island restoration will greatly reduce wave energy in Louisiana's bays and along fringing marshes, additional devices capable of absorbing wave energy around portions of the fringing marshes will likely require construction. This may occur in areas where the fetch permits regeneration of incident waves that have propagated across the Louisiana shelf, or locally generated higher frequency waves.

Stone, G. W., D. A. Pepper, et al. (2004). "Ship shoal as a prospective borrow site for barrier island restoration, coastal south-central Louisiana, USA: Numerical wave modeling and field measurements of hydrodynamics and sediment transport." Journal of Coastal Research 20(1): 70-88.

Ship Shoal, a transgressive sand body located at the 10 m isobath off south-central Louisiana, is deemed a potential sand source for restoration along the rapidly eroding Isles Dernieres barrier chain and possibly other sites in Louisiana. Through numerical wave modeling we evaluate the potential response of mining Ship Shoal on the wave field. During severe and strong storms, waves break seaward of the western flank of Ship Shoal. Therefore, removal of Ship Shoal (approximately 1.1 billion m(3)) causes a maximum increase of the significant wave height by 900%-100% and 40%-50% over the shoal and directly adjacent to the lee of the complex for two strong storm scenarios. During weak storms and fair weather conditions, waves do not break over Ship Shoal. The degree of increase in significant wave height due to shoal removal is considerably smaller, only 10%-20% on the west part of the shoal. Within the context of increasing nearshore wave energy levels, removal of the shoal is not significant enough to cause increased erosion along the Isles Dernieres. Wave approach direction exerts significant control on the wave climate leeward of Ship Shoal for stronger storms, but not weak storms or fairweather. Instrumentation deployed at the shoal allowed comparison of measured wave heights with numerically derived wave heights using STWAVE. Correlation coefficients are high in virtually all comparisons indicating the capability of the model to simulate wave behavior satisfactorily at the shoal. Directional waves, currents and sediment transport were measured during winter storms associated with frontal passages using three bottom-mounted arrays deployed on the seaward and landward sides of Ship Shoal (November, 1998-January, 1999). Episodic increases in wave height, mean and oscillatory current speed, shear velocity, and sediment transport rates, associated with recurrent cold front passages, were measured. Dissipation mechanisms included both breaking and bottom friction due to variable depths across the shoal crest and variable wave amplitudes during storms and fair-weather. Arctic surge fronts were associated with southerly storm waves, and southwesterly to westerly currents and sediment transport. Migrating cyclonic fronts generated northerly swell that transformed into southerly sea, and currents and sediment transport that were southeasterly overall. Waves were 36% higher and 9% longer on the seaward side of the shoal, whereas mean currents were 10% stronger landward, where they were directed onshore, in contrast to the offshore site, where seaward currents predominated. Sediment transport initiated by cold fronts was generally directed southeasterly to southwesterly at the offshore site, and southerly to westerly at the nearshore site. The data suggest that both cold fronts and the shoal, exert significant influences on regional hydrodynamics and sediment transport.

Styan, W. B. and R. M. Bustin (1983). "Petrography of Some Fraser-River Delta-Peat Deposits - Coal Maceral and Microlithotype Precursors in Temperate Climate Peats." International Journal of Coal Geology 2(4): 321-370.

Tanabe, S., K. Hori, et al. (2003). "Song Hong (Red River) delta evolution related to millennium-scale Holocene sea-level changes." Quaternary Science Reviews 22(21-22): 2345-2361.

The Song Hong (Red River) delta occurs on the northwest coast of the South China Sea. Its evolution in response to Holocene sea-level changes was clarified on the basis of sedimentary facies and 14 radiocarbon dates from the 40 m long Duy Tien core from the delta plain, and using previously reported geological, geomorphological, and archaeological data. The delta prograded into the drowned valley as a result of early Holocene inundation from 9 to 6 cal. kyr BP, as sea-level rise decelerated. The sea-level highstand at + 2-3 m from 6 to 4 cal. kyr BP allowed widespread mangrove development on the delta plain and the formation of marine notches in the Ha Long Bay and Ninh Binh areas. During sea-level lowering after 4 cal. kyr BP, the former delta plain emerged as a marine terrace, and the delta changed into the present tide- and wave-influenced delta with accompanying beach ridges. Delta morphology, depositional pattern, and sedimentary facies are closely related to Holocene sea-level changes. In particular, falling sea level at 4 cal. kyr BP had a major impact on the evolution of the Song Hong delta, and is considered to be linked to climate changes. (C) 2003 Elsevier Ltd. All rights reserved.

Touzani, A. and P. Giresse (2002). "The Rhone River Prodelta: Short-term (10(0)-10(3) year) sedimentation patterns and human impact." Journal of Coastal Research 18(1): 102-117.

We compared various data sets obtained on the Rhone River delta and the adjacent land over the past 1000 years. Data sources were historical documentation and quantitative results. The period of the Rhone d'Ulmet (before 1300 y. A.D.) corresponds to the north-western position of the river mouth and to climatic and runoff variations of low magnitude. In the prodelta area, mottled muds are common and laminated muds were not observed due to the distance of collected data from the mouth. The "wild" Rhone period from 1587 to 1869 y. A.D. (Bras de For and Grand Rhone mouths) shows a dramatic extent (7-8 kin distance) of laminated muds resulting from seasonal floods. Changes in climatic conditions probably modified the watershed and played a prominent part in the prodelta development. During this period, pedogenic ochre aggregates were reworked from swamp soils of the delta during channel migrations. In all our cores, the top of laminated muds coincides with the disappearance of the ochre aggregates. The Recent period of the Rhone channeling began with the 1869 rectification which fixed the main channel. The consequence was a drastic reduction of laminated muds to a 3-4 km proximal area off the stabilized mouth. With a decrease in flood supply and a longer time of exposure, we can observe a coarsening trend in the upper part of the cores as a result of repetitive reworking processes. The seasonal build-up of laminites is altered seaward: faintly laminated muds and mottled muds deposition shifted with increasing distance from the river mouth. Markers of the anthropogenic pollution, such as metallurgic microballs (Fe sulfides) and talc characterized the upper third of the cores. A variety of previous sedimentological data and Pb-210 and Cs-137 age estimates indicate very fast sediment accumulation rates in the proximal Rhone prodelta (30-40 cm y(-1)) which would be regarded as apparent rates. Detailed investigation of the gravity cores located off the Rhone River mouth showed marked coarsening-upward trends (condensed section), clast deposition, and truncated structures that indicate the processes of sea floor erosion and reworking. On the distal Rhone prodelta, a thin recent veneer overlies the Holocene tract of the initial transgression and indicates a hiatus of approximate to 5-6000 y. Decreased discharge and reworking have been especially

Uliana, E., C. B. Lange, et al. (2002). "Evidence for Congo River freshwater load in Late Quaternary sediments of ODP Site 1077 (5 degrees S, 10 degrees E)." Palaeogeography Palaeoclimatology Palaeoecology 187(1-2): 137-150.

Late Quaternary fluctuations in the intensity of Congo River freshwater load were reconstructed using three different proxies (marine and freshwater diatoms, and the delta(18)O record of Globigerinoides ruber) preserved in the sediments of Ocean Drilling Program (ODP) Site 1077, located at the northern rim of the Congo River fan (5degrees10'S, 10degrees26'E). An abrupt change in the diatom assemblage is evident at Termination II a two- to four-fold increase in (a) the relative abundance of a marine planktonic diatom tolerant of low salinity conditions (Cyclotella litoralis), and (b) in the concentration of freshwater diatoms. The microfossil data suggest a change in the environmental conditions surrounding Site 1077 from predominantly marine to mixed marine/brackish/fresh. The delta(18)O record of the planktic foraminifera G. ruber (pink) revealed negative deviations from the global oxygen isotope signal since Termination II which occurred during warm stage 1 and substages 3.2, 5.1, 5.3, and 5.5. Comparison of the isotopic signal of ODP Site 1077 with the record from a pelagic location (core GeoB1041 at 3degrees48'S, 7degrees05'W) confirms these results. The construction of an artificial delta(18)O curve using alkenone-derived sea surface temperature (SST) data from a nearby core (GeoB1008 at 6degreesS, 10degreesE) allowed us to estimate salinity and temperature effects on the ODP Site 1077 isotopic signal. Although increased SSTs may account for lighter delta(18)O values during warmer periods, they do not explain the extremely light values documented in the sediments of Site 1077. We used the oxygen isotope difference (Deltadelta(18)O) between our site and GeoB1041 as a proxy for freshwater input. A general trend in the Deltadelta(18)O was observed, with more negative values since Termination II. In addition, conspicuous Deltadelta(18)O negative pulses coincided with periods of northern hemisphere summer insolation maxima over the African continent, suggesting an increase in the freshwater discharge from the Congo River due to enhanced precipitation on the hinterland. Here we propose that the abrupt change in environmental conditions at Site 1077 since Termination II is a consequence of a major reorganization in the depositional environment of the Congo River delta. This reorganization involved sustained equatorward displacement of the Angola-Benguela Front causing a northward deflection of the Congo River plume thus moving plume waters further north than normal and over Site 1077. (C) 2002 Elsevier, Science B.V. All rights reserved.

Urabe, A., M. Tateishi, et al. (2004). "Lake-level changes during the past 100,000 years at Lake Baikal, southern Siberia." Quaternary Research 62(2): 214-222.

Lake-level changes inferred from seismic surveying and core sampling of the floor of Lake Baikal near the Selenga River delta can be used to constrain regional climatic history and appear to be correlated to global climate changes represented by marine oxygen isotope stages (MIS). The reflection pattern and correlation to the isotope stages indicate that the topset and progradational foreset sediments of the deltas formed during periods of stable lake levels and warm climatic conditions. During warm stages, the lake level was high, and during cold stages it was low. The drop in the lake level due to cooling from MIS 5 through MIS 4 is estimated to be 33-38 m; from MIS 3 through MIS 2, it fell an additional 11-15 m. Because the lake level is chiefly controlled by evaporation and river input, we infer that more water was supplied to Lake Baikal during warm stages. (C) 2004 University of Washington. All rights reserved.

Wang, P. X., Y. H. Bian, et al. (1996). "The Younger Dryas in the West Pacific marginal seas." Science in China Series D-Earth Sciences 39(5): 522-532.

The occurrence and nature of the Younger Dryas (YD) abrupt climatic event in the West Pacific marginal sea are discussed on the basis of 15 sediment cores. This event has been found in all these cores studied with a high-resolution stratigraphy and proved to be common to the West Pacific region. As shown by the isotopic and micropaleontologic analyses, the YD, dated by C-14 at about 11 000 to 10 000 a B.P., is a brief event of sea surface cooling in winter season following a fresh-water pulse about 12 000 a B.P. The ''apparent regression'' of the YD recorded in the Changjiang River delta and the Sea of Japan agrees with the interpretation that the YD is a period of slowed sea level rising between two phases of rapid rising. Both the winter surface water cooling and the increasing salinity in the YD imply a strengthening of the winter, but not summer monsoon circulation. This major climatic event in the marginal seas must have had profound impact on the adjacent continent.

Warne, A. G., E. H. Guevara, et al. (2002). "Late Quaternary evolution of the Orinoco Delta, Venezuela." Journal of Coastal Research 18(2): 225-253.

The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel from incising as deeply as many other major river systems. Shallow seismic data indicate that the late Pleistocene Orinoco incised into the present continental shelf, where it formed a braided-river complex that transported sediment to a series of shelf-edge deltas. As sea level rose from 16,000 to 9,500 yrs BP, the Orinoco shoreline shifted rapidly landward, causing shallow-marine waves and currents to form a widespread transgressive sand unit. Decelerating sea-level rise and a warmer, wetter climate during the early Holocene (9,500 to 6,000 yrs BP) induced delta development within the relatively quiet-water environment of the EVB embayment. Sea level approached its present stand in the middle Holocene (6,000 to 3,000 yrs BP), and the Orinoco coast prograded, broadening the delta plain and infilling the EVB embayment. Significant quantities of Amazon sediment began to be transported to the Orinoco coast by littoral currents. Continued progradation in the late Holocene caused the constriction at Boca de Serpientes to alter nearshore and shelf hydrodynamics and subdivide the submarine delta into two distinct areas: the Atlantic shelf and the Gulf of Paria. The increased influence of littoral currents along the coast promoted mudcape development. Because most of the water and sediment were transported across the delta plain through the Rio Grande distributary in the southern delta, much of the central and northwestern delta plain became sediment starved, promoting widespread accumulation of peat deposits. Human impacts on the delta are mostly associated with the Volcan Dam on Cano Manamo. However, human activities have had relatively little effect on the delta processes and environments.

Williams, H. F. L. (1995). "Foraminiferal Record of Recent Environmental-Change - Mad-Island Lake, Texas." Journal of Foraminiferal Research 25(2): 167-179.

Foraminifera were identified in samples from eight lake-bed cores from Mad Island Lake, a tidal lake on the Texas Gulf Coast. Downcore variation in species assemblages forms a chronological record of changing salinity conditions within the lake. An approximate time frame for events recorded within the cores was obtained by Cs-137 dating of three additional lake bed cores, which provides 1954 and 1963 datums. Environmental changes recorded by the lake bed cores include: invasion by foraminifera characteristic of nearshore bay environments following construction of the Gulf Intracoastal Waterway in 1941, presumably due to increased salt water intrusion and a change to more saline conditions within the lake; increased fresh-water influence marked by brackish foraminifera in the late 1950's/early 1960's, possibly in response to a wetter and cooler climatic trend and inputs of irrigation water following the initiation of rice production in the lake's watershed; and a lake-wide, abrupt increase in salinity recording the arrival of Hurricane Carla in 1961. Foraminiferal changes resulting from the hurricane were still evident in 1993, suggesting a recovery time on the scale of decades. Sedimentation rates, derived from 1954, 1961 and 1963 marker horizons, range from 0.1 to 4.5 cm per year. The highest sedimentation rate (4.5 cm/yr) occurred during 1961-63; sedimentation during this period was enhanced by large, short-lived sediment inputs associated with the 1961 impact of Hurricane Carla.

Xu, J. X. (2003). "Sediment flux to the sea as influenced by changing human activities and precipitation: Example of the Yellow River, China." Environmental Management 31(3): 328-341.

Since the 1970s, the sediment flux of the Yellow River to the sea has shown a marked tendency to decrease, which is unfavorable for wetland protection and oil extraction in the Yellow River delta. Thus, an effort has been made to elucidate the relation between the sediment flux to the sea and the drainage basin factors including climate and human activities. The results show that the sediment flux to the sea responds to the changed precipitation in different ways for different runoff and sediment source areas in the drainage basin. If other factors are assumed to be constant, when the annual precipitation in the area between Longmen and Sanmenxia decreases by 10 mm, the sediment flux to the sea will decrease by 27.5 million t/yr; when the precipitation in the area between Hekouzhen and Longmen decreases by 10 mm, the sediment flux to the sea will decrease by 14.3 million t/yr; when the precipitation in the area above Lanzhou decreases by 10 mm, the sediment flux to the sea will decrease by 17.4 million t/yr. A multiple regression equation has been established between the sediment flux to the sea and the influencing factors, such as the area of land terracing and tree and grass planting, the area of the land created by the sediment trapped by check dams, the annual precipitation, and the annual quantity of water diversion by man. The equation may be used to estimate the change in the sediment flux to the sea when the influencing variables are further changed, to provide useful knowledge for the environmental planning of the Yellow River drainage basin and its delta.

Yamaji, K., T. Ohara, et al. (2003). "A country-specific, high-resolution emission inventory for methane from livestock in Asia in 2000." Atmospheric Environment 37(31): 4393-4406.

Methane emissions from livestock in South, Southeast, and East Asia were estimated to be about 29.9 Tg CH4 in 2000 using the Food and Agriculture Organization database and district-level data on regional activity and emission factors, considering regional specificities. These emissions consisted of 25.9 Tg CH4 from enteric fermentation and 4.0 Tg CH4 from livestock manure management systems. India had the greatest production, with 11.8 Tg CH4 from livestock, primarily cattle and buffaloes. China was also a high-emission country, producing about 10.4 Tg CH4. To determine their spatial distribution, emissions at the country and district levels were plotted on a 0.5 x 05degrees grid according to weight, using high-resolution land cover/use datasets. This gridded database shows considerable emissions throughout the Ganges basin, with peak emissions exceeding 30 Gg CH4 grid(-1) in the Ganges River delta. The total methane emissions from livestock increased by an average of 2% per annum from 1965 to 2000. The recent increase in methane emissions in China was especially remarkable. (C) 2003 Elsevier Ltd. All rights reserved.

Yi, S., Y. Saito, et al. (2003). "Vegetation and climate changes in the Changjiang (Yangtze River) Delta, China, during the past 13,000 years inferred from pollen records." Quaternary Science Reviews 22(14): 1501-1519.

A high-resolution pollen record from 2 boreholes from the Changjiang (Yangtze River) delta shows a series of well-defined changes in vegetation and climate over the last 13, 000 yr. In latest Pleistocene to early Holocene time (12,900-10, 300 cal yr BP), pollen dominated by the xerophytic herb Artemisia and common conifers indicate coniferous forest and grasslands and a cool, dry climates, possibly represented by the Younger Dryas. From 10,300 to 9000 cal yr BP, a warm, wet climate fostered the development of mixed broadleaved evergreen-deciduous forests to grow on the grasslands and surrounding hills and uplands. From 9000 to 7600 cal yr BP, the dominance of conifers and the reduction in broadleaved evergreen trees pollen suggest cool, dry conditions. The mid-Holocene "hypsithermal" (7600-4800 cal yr BP) is represented by a large expansion of subtropical evergreen-deciduous broadleaved forests. Between 4800 and 1300 cal yr BP, which corresponds to a Neoglacial period elsewhere, conifers are dominant, along with common herbs, whereas the area with broadleaved evergreen trees shrink under the cool, dry conditions. The first occurrence of Fagopyrum pollen at 4500 cal yr BP suggests human influence. The significant change in arboreal and herbaceous pollen after 1300 cal yr BP reflects widespread intensive human influence. (C) 2003 Elsevier Science Ltd. All rights reserved.

Yi, S., Y. Saito, et al. (2003). "Holocene environmental history inferred from pollen assemblages in the Huanghe (Yellow River) delta, China: climatic change and human impact." Quaternary Science Reviews 22(5-7): 609-628.

Palynological analyses of two boreholes from the Huanghe (Yellow River) delta, China, provide a palaeoenvironmental history of the last ca 12 kyr, particularly of millennial scale climatic changes and human impacts on the Huanghe drainage area for the last 4.5 kyr. In the Late Pleistocene (12 cal. kyr BP), fossil floras dominated by the xerophytic herb Artemisia reflect short-term climatic deterioration possibly Younger Dryas. Holocene 'hypsithermal' climatic conditions from 9.8 to 4.5 cal. kyr BP allowed monsoonal evergreen and broadleaved deciduous forests to thrive. From 4.5 to 1.3 cal. kyr BP diverse broadleaved deciduous trees and herbs flourished, although the climate was slightly cooler than previously, corresponding to a Neoglacial period elsewhere. However, minor warm events were recorded for 2.7-2.3 and 1.7-1.3 cal. kyr BP within this neoglacial period. A period of non-deposition occurred, from 1.3 to 0.21 cal. kyr BP because of the shift of the Huanghe to a different mouth and, following this period, the climate was cooler. Palaeoecological data indicate that human-induced vegetational changes occurred mainly at ca 4 and 1.3 cal. kyr BP as a result of deforestation and agricultural cultivation. (C) 2002 Elsevier Science Ltd. All rights reserved.

Zalidis, G. (1998). "Management of river water for irrigation to mitigate soil salinization on a coastal wetland." Journal of Environmental Management 54(2): 161-167.

The change in water chemistry in the Aries River delta wetland is due to the interruption of river discharge in this area during the irrigation period. The impact, which Visibly affects the wetland's flora, was verified by measuring water salinity in the delta area during the peak irrigation period. Given that additional water supplies are not available, the only way to remedy this problem is to use the available irrigation water wisely. Most irrigation wafer losses are attributed to the fact that the constant water delivery rate does not respond to water demand of the irrigation networks. To cope with this problem, a water resources management system, based on the assessment of wafer requirements, was developed. The system can schedule water supply to the irrigation networks, thus saving enough water to maintain discharges at the delta and to keep water salinity within to acceptable levels. The water resource management system, which was based on fully distributed real time inputs (climate data), was developed using a Geographic information System (GIS). This system adjusts network irrigation supply through a feedback mechanism. This mechanism responds to the changes that might occur in the exogenous system inputs: effective rainfall (R-e) and actual evapotranspiration (ETr), and to the difference between the system's target and calculated e(p) values. In this way irrigation water is used efficiently, thus minimizing the degradation of natural resources. Using the proposed method if was found possible to remedy the environmental impact of agriculture by saving enough fresh wafer to maintain the biotic and abiotic parameters of the natural ecosystem. (C) 1998 Academic Press.