A FRAMEWORK FOR REASSESSMENT OF BASIC RESEARCH AND
EDUCATIONAL PRIORITIES IN HYDROLOGIC SCIENCES
V. Gupta, University of Colorado
C. Duffy, Penn State University
R. Grossman, University of Colorado
W. Krajewski, University of Iowa
U. Lall, Utah State University and Columbia University
Mark McCaffrey, Boulder, Colorado
B. Milne, University of New Mexico
R. Pielke Sr., Colorado State University
K. Reckhow, Duke University
F. Swanson, US Forest Service
*A large number of people have contributed to this effort. Their names are listed under 'Contributors and Acknowledgements'
Report of a Hydrology Workshop, Albuquerque, NM, Jan. 31- Feb.1, 1999, to the NSF-GEO Directorate
Report Date: July 4, 2000.
TABLE OF CONTENTS
- THE WEB IMPERATIVE
- VISION STATEMENT
- SOCIETAL RATIONALE
- SCIENCE CHALLENGES
- WEB IN RIVER BASINS AS AN ILLUSTRATIVE THEME FOR RESEARCH AND EDUCATION
- WEB INFRASTRUCTURE
- IMPLEMENTATION STRATEGIES AND RECOMMENDATIONS
- CONTRIBUTORS AND ACKNOWLEDGMENTS
4.1 WEB Research Pathways 4.2 WEB Domains 4.3 WEB Scales
- 4.3.1 Global Scale
4.3.2 Continental Scale
4.3.3 Drainage Basin (Aquifer) Scale
4.3.4 Hillslope to Watershed Scale
5.1 Suggestive Hypotheses
- 5.1.1 Earth-Related Processes
5.1.2 Atmosphere-Related Processes
5.1.3 Climate-Related Processes
5.1.4 Geochemical Processes
5.1.5 Ecological Processes
- 5.2.1 Graduate & Undergraduate Education
5.2.2 K-12 School Education
5.2.3 A WEB-Science for the Public
6.1 Choosing Candidate Natural Laboratories
6.2 Laboratory Management
- 6.2.1 Science Steering Group
6.2.2 Instrumentation Deployment
6.2.3 Data Management
6.2.4 Educational Challenges
6.2.5 Technology Transfer
7.1 Implementation Strategies 7.2 Selection Criteria
7.3 Establishing WOSS
Hydrologic Science is growing in many directions since its emergence as a distinct interdisciplinary Geoscience in 1991. Water cycle research is following four main pathways (scaling, coupling, diagnosing, and modeling), while striving to reach consistent conclusions in the face of space-time variability and dynamic nonlinearities that confound cross-scale computations and understanding. Research is being pursued in four separate domains (water cycling, energy, earth structure, and ecology), while striving to understand the ties among them. The consensus is to develop an integrative hydrologic science focused on the central role of the water cycle in linking landscapes, atmosphere and oceans, geochemistry, and biota from molecular to planetary spatial scales and from instantaneous to millennial time scales. This report is the product of extensive interdisciplinary deliberations on these issues for almost two years. It proposes the scientific pursuit of a quantitative understanding of Water cycle interactions with the entire Earth system and Biota, called WEB.
The WEB concept addresses the large knowledge gap in structure and coupling of water, energy, material and ecological balances of Earth. Learning how water interacts with physical media that have diverse chemical characteristics in dynamic environments would provide much needed understanding of this complex system. With this information, managers and policy makers would be better positioned to guide and sustain development and management of our natural resources to serve the growing human population while protecting our environment from overuse and abuse. Growing public interest in these issues offers unprecedented support for research to make major scientific advances in the next decade. The stakes are large, as society is making critical decisions with a fragmentary understanding of how water use and other human activities impact climate, the quality and quantity of water resources, hazards such as floods and droughts, and the health of terrestrial and aquatic ecosystems.
The foci of WEB are the complex bio-habitats that embed wetlands, drainage basins, lakes, aquifers, tropical rain forests, and the entire planet Earth with the biosphere. New advances in nonlinear science offer an unprecedented opportunity for making great strides in this integrated WEB science in the next decade. Progress toward this WEB ideal will require an observation system that compiles and freely distributes coordinated data sets on WEB-related processes at a variety of space and time scales. Research and measurement must be planned together. Continued progress will also require an interdisciplinary initiative for education and public outreach. It will enable students and the general public to understand the unique role of the planetary water cycle in the co-evolution of life and a habitable climate on Earth for 3.8 billion years, and for understanding and solving the water problems facing society and the science.
The vehicle proposed to implement WEB is a network of "natural laboratories" in key geographic areas eventually linked by a "National Hydrologic Facility." Such a system would design and facilitate deployment of cutting-edge instrumentation, support field observations, and support the organization, analysis and management of community data sets and models. Science issues that require focused data collection, hypotheses development and tests, and that have the potential for significant cross-disciplinary theoretical advances, are identified in a river-basin context as an illustrative example. A number of other settings should be similarly examined. Strong partnerships between the academic community and multiple federal agencies are essential for progress.
1. THE WEB IMPERATIVE
"Hydrologic Science" emerged as a distinct, interdisciplinary Geoscience through a report of the National Research Council (NRC, 1991), called "Opportunities in Hydrologic Sciences (OHS)". That report defined Hydrology as covering 'Continental water processes and Global water balance' with interfaces to physical, chemical, and biologic processes governing Earth's hydrologic cycle over a wide range of space and time scales (NRC, 1991, p. 4). OHS set forth critical and emerging science areas, data and educational requirements, and broad priorities (NRC, 1991, pp. 9-16). Its publication led to the establishment of a new funding Program in Hydrologic Sciences within the Division of Earth Sciences of NSF. This program has since been nurturing a research community focused on building the science of hydrology. There have been recent efforts to assess the progress in Hydrologic Science since the publication of OHS (NRC, 1998) and its role for the US Global Change Research Program (1999a).
Now, Hydrology and related sciences stand at the door of a tremendous opportunity to improve the management of our limited and threatened water resources. Advances in science and technology are laying the foundation for a more holistic intellectual framework supported by systematic measurement and data compilation at multiple, and particularly larger, scales. The vision of what can be accomplished has brought us together from many branches of water science and engineering, from both government and academia, to initiate a broad, new interdisciplinary framework for research and education in Hydrologic Science. We call this framework and support system WEB: Water, Earth, and Biota.
The imperative that drives WEB is that holistic study of water interactions with landscape, geochemistry, and biota is essential for a quantitative understanding of the planetary water cycle. The focus is on the major scientific challenges in understanding its terrestrial components. Holistic study is essential, because every part of nature functions as a context for every other part. This relational context harbors many interdependencies that can only be defined quantitatively by extensive research that deploys new technology to supplement measurements presently available.
Key issues for working in this contextual foundation are:
- Water is the life-blood of the planet. The water cycle comes together at the planetary scale and must be studied as a planetary process to gain holistic understanding.
- Water studies have been intellectually partitioned into domains by regional interests, agency missions, disciplinary training, and the institutionalization of field experiments.
- Scientists working in each domain increasingly recognize that their findings depend highly on boundary conditions at the interfaces with the other domains
- As demands on a fixed quantity of water increase and adversely impact the environment, water managers are driven to greater efforts to contain floods, droughts, and contamination while being increasingly stymied by an inadequate science framework for quantifying feedbacks among the domains.
- Research is needed to assess and extend the predictability of hydrologic systems at many scales to allow better risk and vulnerability assessments that support resource management decisions.
- Progress toward this WEB ideal will require an observation system that compiles and freely distributes coordinated data on WEB-related processes at a variety of space and time scales. Research and measurement must be planned together.
- Continued progress will also require an interdisciplinary initiative for education and public outreach that will enable students and the general public to think about water issues from both planetary and local perspectives.
WEB must evolve in stages. We offer this report as a starting point to challenge scientists and engineers to reflect on where we are and to work together in moving forward. The essential ingredients are creative thinking and flexible arrangements, so that new ideas and methods can be readily adopted.
2. VISION STATEMENT
WEB addresses the central role of water in linking landscapes, atmosphere and oceans, geochemistry, and biota in spatial scales from the molecular to the planetary, and in temporal scales from instantaneous to geologic. This perspective of interconnectedness at multiple scales is fundamental to gaining holistic understanding of the complexity of nature and changes over space and time through interactions with humans. Increasing threats to natural environments make this broad vision critical for the management of water and other natural resources to sustain growing human populations and modernizing economies. The WEB vision does not stop with the importance of the topic and the definition of science goals; it identifies a path for moving forward.
3. SOCIETAL RATIONALE
Life on Earth has been evolving for 3.8 billion years. Over this long time, our planet has experienced multiple astronomical, volcanic, and other disruptions, and yet it has demonstrated great resilience as life has survived and continued to prosper. Over recent decades, it has become evident that humans have a major impact on planetary terrestrial and marine net primary productivity (Vitousek and Matson, 1993). The margin of safety for the human/environment enterprise is small under any scenario of doubling the current human population of 6 billion, or even increasing it by just 30-50%, to 8-9 billion. A fully integrated view of the relevant sciences is needed to address impacts of this magnitude. WEB will address the central aspects of human systems that impact productivity. These aspects include climate, erosion, land use practices, water supply, and education.
The basic needs of human beings, their economic prosperity, and the vitality of all life on Earth depend on water. Consequently, societal infrastructures have evolved to manage water resources for human consumption, for agriculture and energy production, to reduce losses from natural hazards, and to regulate water quality to preserve species diversity. These apparently disparate goals are represented as the missions of distinct branches of government. It is consequently no surprise that hydrologic research has evolved on parallel, disjunctive paths. The resulting fragmented knowledge has left large gaps in our understanding of how water use and other human activities impact climate, the quality and quantity of water resources, hazards such as floods and droughts, and the health of terrestrial and aquatic ecosystems. There are many examples of how this has led to decisions that resulted in high societal cost. Channeling and damming rivers, deforestation, soil fertilization, draining wetlands, using natural waters for cooling of power plants, and adding MTBE to gasoline solved some problems, but often created greater difficulties. A need for removing some of the existing dams, which brought irrigation, energy production and flood control benefits, has arisen out of their adverse impact on fisheries and natural habitats (Reisner, 2000). This is an example of how changing societal values and the multi-faceted impacts of human intervention in the natural system translate into needs for new, integrative scientific information. A recent report of the NRC (1999b), 'New Strategies for America's Watersheds,' has made the case that an integrated scientific approach is necessary for managing watersheds.
As society becomes more reliant upon the dependability of technology and as populations and infrastructure increasingly become geographically concentrated, the nation's susceptibility to hydrologic hazards is increasing at an alarming pace. For example, in recent decades, over 80 percent of presidentially declared disasters have been floods, and have resulted in billions of dollars in losses (National Mitigation Strategy, 1995). Severe chemical and organic contamination of water has been reported in virtually all parts of the Earth. Dramatic shifts in land cover have changed both water quality and quantity. As an example, in Florida, forests have been cut for production of cattle, wetlands drained for growing sugar cane, and urban centers have built impervious hardscapes and stressed ground and surface sources of fresh water. The U.S. Army Corps of Engineers and the State of Florida are initiating a $7.8 billion project to restore the Everglades. At this juncture, one asks the science and engineering communities what they wish they had understood about ecology and hydrology to have avoided this situation. What needs to be scientifically understood now, as further modification of the system is undertaken; and what knowledge is needed in other climate and biome regimes to avert catastrophe (Nuttle, 1999). It is clear that major scientific advances are necessary to assess vulnerabilities of habitats and ecosystems to natural and anthropogenic perturbations.
However, water resources research has been active. Governments have long invested in data collection and modeling to address a multitude of topics, so why do these societal challenges continue to persist? As already mentioned, one key problem is a fragmented understanding of WEB. Another problem is weak integration. The present challenge is to work from societal concerns to develop a holistic scientific understanding of the role of water in an ever-dynamic environment. WEB proposes a holistic intellectual culture in academia, and strong partnerships between the academic community and multiple federal agencies
4. SCIENCE CHALLENGES
The challenge to WEB science is that important water management problems can only be adequately addressed from a holistic view of the water cycle in a world with "hydro-geo-bio-complexity." Progress requires identifying pieces and their systematic integration. Present efforts in hydrologic science are deploying four main research pathways while striving to reach a common end, operating in four domains while seeking a unified approach, and confronting dynamic nonlinearities that confound cross-scale computations and understanding.
4.1 WEB Research Pathways The four main pathways: scaling, coupling, diagnosing , and modeling, are common to most natural and engineering sciences and provide a broad framework for WEB research and education.
The hydrologic cycle operates simultaneously, interactively, and continuously through the atmosphere, oceans and continents at multiple scales in space and time. Often, we do not even know which scales are important or how the important scales are inter-related. WEB science needs tools to scale up from a microscopic scale and to scale down from the planetary scale. Particular difficulty exists in bridging the intermediate scales of watersheds with the planetary scale.
The hydrologic cycle is closely entwined with many other Earth processes. Water is the primary driving force behind erosion and sedimentation, which shapes the Earth's surface. Water-borne transport drives biogeochemical interactions on land, in oceans, and within the Earth's crust. As the main constituent of living organisms, water is fundamental to the existence of life. Water split by photosynthesis is the primary source of atmospheric molecular oxygen for respiration. WEB science proposes rigorous study of couplings among physical, chemical, and biological processes.
Past estimation of hydrologic fluxes has been empirical and plagued by unquantifiable uncertainties. We still do not understand many primary feedbacks and thresholds governing hydro-bio-geo-complexity. WEB-Science needs new measurements and a more systematic framework for integrating data being collected into a widely usable resource. Investments in modern technology to broaden the observational base would support exploratory testing toward developing new theories.
Modeling provides a powerful tool in developing theory. Models of complex nonlinear and chaotic systems can combine ideas from process or dynamics, pattern or geometry, and probability or uncertainty. By using new technologies for measurement and new methodologies for analysis, WEB models would discover new laws governing water fluxes and associated chemical, biological, and landform processes. However, success requires moving from traditional hydrologic perspectives of plots, hillslopes, or drainage basins to a multi-scale, multi-process WEB view. It requires judging models not by how well simulations match measurements, but by how effective the modeling is in identifying gaps in understanding and new science issues. The needed change in mindset is already seen in the recommendations different groups are making for the future of Hydrologic Science (James, 2000).
4.2. WEB Domains
Four pathways are being used to study the complex habitats supporting aquatic and terrestrial ecosystems in watersheds, drainage networks, aquifers, wetlands, lakes, rain forests, etc. Each setting supports a habitat and contributes to the economy. Studies for understanding how a habitat is tied to its setting requires investigations regarding water fluxes, transport of nutrients and pollutants, and energy transfers through solar radiation and gravity. It also requires understanding how the soils and rocks evolve over geologic time, and how biological organisms modify processes, consume energy, alter structure, and themselves evolve over time. The needed studies can be considered in four domains, which are similar to the four domains described in a ten year planning report "NSF Geosciences Beyond 2000".
Our supply of fresh water is drawn from the hydrologic cycle. The sediments and solutes carried by moving water deliver nutrients, export wastes, and support biogeochemical cycling. At a much slower pace, the crust of the solid Earth is itself cycling as revealed by studies in tectonics. Organisms have an important role in altering both water-borne transport and physical properties on Earth materials. A quantitative understanding of how biotic factors impact biogeochemical cycles requires studies into the role of the water cycle in the development and composition of biological habitats in soils, sediments, lakes, aquifers, river basins, and forests. Interactions across scales in space and time influence the water cycle from the "local" to the "planetary" scale.
Solar energy and gravity are the two principal sources of energy that drive cycling. Solar energy supplies water vapor to the atmosphere by evapotranspiration from ocean and land surfaces. Water vapor is Earth's dominant greenhouse gas and is the primary carrier of atmospheric energy. Vegetation, soils, and land-surface conditions, including snowpack, can change surface albedo and cloudiness, modify radiative and water balances, influence regional flood (US Upper Midwest in 1993) and drought regimes (Sahel in 1970s, US Midwest in 1988, and US Northeast in 1999), and alter terrestrial and aquatic habitats suddenly and dramatically. Precipitation loads the surface with potential energy that is then dissipated by gravity through complex processes of flow, sedimentation, and terrain formation. Fluid mechanics and bifurcation theories show that flow exhibits subtle instabilities that induce complexity in virtually all aspects of transport. The energy available at different scales and to different processes constrains the dynamics in ways that guide the self-organization of the system in space and time. Developing a quantitative understanding of how the water cycle is coupled to energetics in landscape and ecosystem evolution at scales from planetary to local is a major scientific challenge.
Water fluxes occur from seconds to millennia over and around heterogeneous and ever-changing surfaces. Over geologic time, water has shaped the top layer of solid Earth as a highly heterogeneous soil-rock medium. Basic understanding is needed of the mechanisms through which water fluxes shape topography, soils, and aquifers (precipitation, evapotranspiration, soil wetting, aquifer recharge, and surface and subsurface flow). The dynamics in the evolution of water and biogeochemical fluxes may well be organized into space and time regimes, representing transitory equilibria. A major challenge is to understand the factors that may lead to transitions between such regimes, and hence surprises for resource management. A complementary major challenge is to develop quantitative understanding of the geometry and statistics that describe spatial variability in topography, soils and aquifers as products of the processes that form them. Such understanding would form the basis for defining structure where measurements are difficult.
The WEB perspective expands the scope of hydrologic sciences from a physical-chemical view of water cycling in Earth systems to encompass an underlying paradigm of ecology. Ecology would then be in a position to look at the diversity of ecosystems as products of interactions throughout an evolutionary history that is contingent upon the soils and water bodies inhabited by the organisms. For example, hypotheses on eco-hydrologic equilibrium are receiving growing attention in the literature (Hatton et al., 1997). Quantitative understanding of planetary ecology will include the role of the hydrologic cycle in planetary structure, planetary energetics, and biotic evolution. The transpirative fraction of evapotranspiration corresponds to plant metabolism (Enquist et al. 1998) and therefore has an evolutionary context. The information storage in evolving genomes is a dynamic process unique to biology but currently is outside the domain of physics (Rosen 2000). Transpiration plus soil evaporation control net primary production, a major ecosystem function that constitutes the source of food and fiber. WEB interactions have produced millions of species and trillions of individuals embedded in the structure upon and within which ongoing cycles unfold.
4.3 WEB Scales
The many interactive and nonlinear processes within the WEB domains have shaped the present hydro-bio-geo-complexity. WEB research would work with different scales and levels of complexity and also cascade across scales and levels. The following examples are offered to explain what this means.
4.3.1 Global Scale
Global climate varies as a result of complex, nonlinear couplings involving water cycle in ocean, atmosphere, and land. The maintenance of a stable environment by the world's biota is perhaps the most significant phenomenon in ecology (Reiners, 1988). Atmospheric water vapor and the conflicting effects of clouds on radiation (Webster, 1994) are linked to the hydrological cycle via cloud formation, precipitation, and evapotranspiration. We are far from a quantitative understanding of: (a) the role of the water cycle and biota in critical relationships that govern natural quasi-oscillatory climate variability at interannual, interdecadal and longer time scales, (b) the combined effects of these interactions, and (c) the robustness of world climate to anthropogenic impacts. Large-scale organized components of the hydrologic cycle, such as monsoonal systems, significantly influence seasonal and longer variations in vegetation and may in turn be influenced by large-scale land use changes. These issues need to be investigated in the context of the hypothesis that global climate is a self-regulating emergent phenomena due to nonlinear coupling between biota and the rest of the Earth system (Lovelock, 1995).
4.3.2 Continental Scale
At the continental scale, self-organizing geophysical and biological processes
There is a critical need to formulate and test hypotheses on how the dynamics of large-scale, land-atmosphere interactions lead to severe and extensive droughts and floods. Droughts worsen with depleted soil moisture and biotic water uptake. Wet conditions produce positive feedbacks that exacerbate regional flooding and produce episodic aquifer recharge. Landscapes directly and indirectly influence Earth's energy and water budgets through biophysical, biogeochemical and biogeographic effects. Major advances are needed to:
- Elucidate feedbacks and fluxes among soil moisture, atmospheric moisture, and ecosystem metabolism and development;
- Identify key hydrological pathways in the physical and chemical coupling of aquatic and terrestrial ecosystems;
- Characterize hydrological-ecological feedbacks that determine surface temperature;
- Assess the risks from human-induced land-use changes on global, regional and local climates that can be as large or larger than those from the radiative effect of a doubling of greenhouse gas concentrations;
- Detail the role of arid vadose zones as sources and archives of paleoclimates and paleorecharge (Tyler et al., 1996). Studies that couple paleoclimate variability with ground water can answer fundamental questions regarding water transport and supply.
Gains in understanding these issues can greatly reduce uncertainty in predicting climate conditions and water availability.
4.3.3 Drainage Basin (Aquifer) Scale
Drainage basins, with length scales of 0.1-1000 Km, are the fundamental units of landscape organization and the basic units for surface water balance studies. Aquifers provide the basic units in the subsurface. Discrete networks embedded in drainage basins organize hydrologic, biogeochemical and ecological processes. In the subsurface, aquifers integrate past organizing processes as changes over time have produced fracture networks. Example scientific problems (emphasizing surface basins within the limited space available) include:
- Couplings among weather and climate, surface soils and geology, and vegetation;
- Erosion and fluvial transport and deposition of sediment in landscape evolution;
- Mobilization, transport, transformation, and deposition of contaminants;
- Process mechanisms for precipitation, evapotranspiration, recharge, and runoff generation and transport across multiple scales of drainage networks
- Extrapolation of measurements from gauged points to other locations and to indicate conditions over zones for studies at larger scales;
These issues are developed further in Section 5.1 as an illustrative example for conceptual development throughout hydrologic science.
Urbanization and intensive agriculture have contaminated surface and ground waters, producing adverse biological, chemical and health effects. Solute transport in the vadose zone exhibits unstable wetting fronts, preferential flows, and heterogeneous chemical and biological reaction pathways. The discovery and documentation of chemical and biological mechanisms in laboratory-scale experiments have not resulted in commensurate understanding at the watershed scale. No framework exists to upscale biochemical processes in generally nonlinear hydrogeological settings. Most field-scale efforts are focused on a few well-studied sites, e.g., the Cape Cod sewage plume, which are not representative of subsurface environments in other geologic settings. Chemical interactions between solute and solids (including microbes) depend on pH and redox, which largely determine contaminant mobility and bio-availability. Large-scale field experiments are needed in a variety of geological settings to upscale biochemical process rates and storages in these settings. Measurements, diagnoses and new modeling efforts are needed to characterize the fundamental processes to assess the vulnerability of water quality. They have important applications in managing nonpoint-source pollution.
4.3.4 Hillslope to Watershed Scale
Hillslope, with length scales of 1-100m, is a fundamental unit in drainage-basin organization. Hillslope processes are critical to understanding the partitioning of surface, near-surface and subsurface runoff generation, patterns and dynamics of vegetation growth, distributions and loadings of non-point-source contaminants and particulates in streams, the isotopic composition of runoff, and the role of hydrology in modulating biogeochemical reactions in complex terrain. Research is needed to develop and test physical and biogeochemical models that apply directly at this scale. Precise methods are needed to effectively characterize interactions among plants, animals, water and soils in watersheds covering a number of physiographic, climatic, and ecological settings; and to extend our understanding of these processes from the hillslope scale to drainage basin scale via a network-based formulation. Pathways in networks produce the micro environments for biogeochemical reactions in the hyporheic zone, where stream water may mix with ground water with quite different chemical properties. The characterization of these reactions within the dynamics of the water cycle is essential to progress in WEB science.
4.4 WEB Integrations
The WEB vision is to bring all the above together by using the four research pathways to determine how the four domains act together and how these ties are cross-connected among scales in the total earth system.
4.4.1 Among Research Methods
Science has been handicapped by barriers among disciplines, and by a lack of WEB principles, integrative mathematical theories and models, and data bases for working across scales. New and greater efforts are needed which can combine scaling, coupling, modeling and diagnosing to bring the descriptive and the quantitative together in developing an integrated WEB science.
4.4.2 Among Domains
Research in each of the four domains has accomplished a great deal, but researchers pursuing water balance, energy balance, earth structure, and ecology tend to treat science across boundaries in other domains superficially. The imperative for the interdisciplinary research grows ever stronger.
4.4.3 Across Scales
Research quantifying processes at each scale encounters major discrepancies when attempting to apply findings to larger or smaller scales. New tools for scaling are emerging, but progress has been slowed by limited data. Consistent cross-scale measuring may well be as difficult as matching results with cross-scale modeling, and building a data base that can be used across scales may well prove to be the greatest challenge to WEB.
- Computational methods for high resolution, multi-scale hydrologic systems.
- Ground water-surface water interactions, plant water uptake, nutrient mixing and transport in the riparian zone, and river basin scale impacts on aquatic ecology.
- Interpretation of isotope-fluid flow distributions in space-time across soil profile, watershed and river basin scales.
- Point-source subsurface flow/transport/growth for multi-phase flow, bioremediation and microbial dynamics affecting regional aquifer resources.
- Modulation of regional flood potential by interannual and longer global climate variability.
- Regional drought dynamics as an interaction between local vegetative and soil moisture state and large-scale atmospheric circulation.
- Interaction among large-scale climate variability, local weather, vegetation, terrain, hillslope erosion and channel sediment transport, leading to regional river sediment loads.
- Phenological changes in hydrology and ecology at continental or basin scales in response to interannual and longer global climate variability.
4.5 Data Base Development
Individual investigators do valuable work with data from field plots and laboratory benches at scales down to soil pores, stomata, and molecules. However, work on important issues at hillslope and larger scales requires a much larger and more costly observing system than can be justified to support individual-investigator research.
Team efforts will have to work from a common data base. Since teamwork does not just happen, some sort of "virtual laboratory" is needed to bring folks together. WEB presents a strategy for team building. We introduce the words "natural laboratory" and "national facility" while recognizing that implementation requires a continuing reaching out to more scientists while maintaining rigorous peer review on basic principles.
The growing distributed archive of Earth-observations provides a valuable starting point. Available data bases include the historical streamflow and sediment stations of the USGS, NOAA climate stations and radar instrumentation (WSR-88D), USDA soils data, and NASA satellite data on high-resolution topography, e.g., Shuttle Radar Topographic Mission (SRTM) and multispectral sensors, e.g., moderate resolution imaging spectrometer (MODIS). Experimental watersheds of the USDA Agricultural Research Service and Forest Service as well as the Long-Term Ecological Research (LTER) sites provide long-term local coverage for many important variables at small space-time scales. Past efforts to coordinate measurements among sensors and technologies must be intensified to gain the ability to address science questions within the WEB imperative.
The recent research thrust on global change has generated a number of science-driven experiments. The Global Energy and Water Cycle Experiment (GEWEX) fostered growing international cooperation in gathering data around the world and promoting modeling at the global scale related to water and associated carbon cycling. Fluxnet was implemented as a global terrestrial network of integrated flux tower, flask, and Earth Observation System data support ecosystem models (Barnes et al., 1998, Running et al. 1999). BOREAS joined an interdisciplinary team to take observations over a 1000 x 1000 km area covering much of Saskatchewan and Manitoba, Canada (Sellers et al. 1997) on airborne fluxes, meteorology, hydrology, remote sensing, ground measurements, tower fluxes, and trace gas biogeochemistry. Similarly, FIFE was a large-scale climatology project set in the prairies of Kansas, dedicated to understanding carbon and water cycles (Sellers et al. 1992). The project involved extensive coordination of data collected by satellites, aircraft, and ground instruments, all of which focused on measuring the coupled cycles of matter and energy flow. Another example is the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), a multi-institutional, international effort to address biogeographic and biogeochemical responses to climate variability and other drivers in both space and time (Kittel et al. 1995). The work compares models of biogeochemistry and vegetation distribution. Model sensitivity is investigated with respect to changing climate and elevated atmospheric carbon dioxide. Woodhouse and Overpeck (1998) demonstrated the utility of diverse paleo indicators in reconstructing drought in the Central United States for the last 2000 years. Paleo information has also been used to improve estimates of flood frequency (Enzel et al, 1993; Stedinger and Cohn, 1986).
Nevertheless, these exemplary efforts by talented and dedicated scientists supported by continuing agency programs are not sufficient. We are a long way from adequately characterizing surface and subsurface properties, understanding process sequences leading to extreme conditions (floods and droughts), or crossing scales in time and space. Integrated characterizations of antecedent and teleconnection effects at all time scales are needed for closures of material and energy budgets. Since many existing data sets are recorded at commensurate space and time scales, we need to work toward consistent, long term (e.g., 100-year) benchmark data sets to facilitate exploration of WEB dynamics at and across a variety of scales. Often raw data need processing. For example, streamflow is affected by diversion, storage, and channelization; and important hydrologic issues are best examined by reconstructing long records adjusted for such effects. Physical principles and statistical procedures are needed to check raw data series and to make reconstructions spatially and temporally consistent. Products need to be made readily accessible to all.
5.0 WEB IN RIVER BASINS AS AN ILLUSTRATIVE THEME
FOR RESEARCH AND EDUCATION
The WEB perspective to water research is needed to understand surface drainage, aquifer, wetland, lake, rain forest, and other settings. A greatly enhanced understanding requires that research methods must integrate scaling, coupling, diagnosing, and modeling while making added use of modern instrumentation to obtain more reliable and extensive measurements than available at present. As research at the larger scales in these settings would be a new sort of an interdisciplinary endeavor, we expect considerable trial and error, particularly in the early stages, both with respect to how to organize measurements and how to conduct research.
For discussion purposes, we call this evolving framework a "Natural Laboratory." The framework needs to tie local measurements to scales all the way up to the planetary as better understanding of global climate is necessary to understand natural variability at the smaller human scales. Comprehension of natural variability provides a starting point for understanding how human interventions impact the environment and how that knowledge can be used in management practices that better serve social needs.
Such a WEB framework would work from hypotheses on system functioning and evolution to propose integrated, sustained, reliable data collection and interpretation and a work plan to use the data to test the hypotheses. The findings of individual studies would suggest new hypotheses and supplemental measurements to support a new work plan. Over time, sequential studies in diverse settings would impart a systems context to (a) data collection and data base development, (b) diagnostic and exploratory analyses to test hypotheses, and (c) modeling to ascertain system predictability, vulnerability and adaptability.
At the next level, several such laboratories could be networked in what we call a "National Hydrologic Facility." As an example, a natural laboratory could focus on the functioning of a particular river basin, and the network could grow through extensions to other river basins to cover a diversity of natural and human-dominated environments and to other types of systems. The process can be illustrated by discussing the study of a river basin as a first step toward WEB's potential contributions.
5.1 Suggestive Hypotheses
We are making progress toward understanding how river basins integrate physical, chemical, and biological processes in the spatial and temporal organizations of fluxes and structures and now need to focus on the dynamics of how these processes integrate in the evolution of planetary structure and life environment. As example research challenges, we hypothesize:
- The river basin is a self-organizing system. The space/time distributions of water, chemicals, and biota guide the evolutions of land structure, drainage networks, habitats, and life itself.
- River basin-scale processes modulate local processes and thereby alter weather, geochemical fluxes, habitats and biodiversity, impacts to be captured in downscaling.
- They also impact global climate by the way they partition land-atmosphere-ocean fluxes and recharge to/discharge from aquifers, impacts to be captured in upscaling.
- The water and energy fluxes through ocean, atmosphere and land at multiple scales in space and time interact through strongly nonlinear connections. These connections must be defined and quantified to simulate planetary environmental dynamics.
- Human modification to a river basin alters local structure and fluxes in ways that have significant impacts on both the upscaling and the downscaling.
Scaling issues are ubiquitous throughout WEB. Mobilizing the data, information, and methodology to test such hypotheses would be the mission of the "Natural Laboratories."
5.1.1 Earth-Related Processes
Diagnosis and modeling of processes at the river-basin scale face complex interactions among subsystems over a wide range of space and time scales. Principles of conservation of mass and energy applied to structure fluxes at different scales can open the door to a general approach to scaling. Power law relationships found by empirical scaling in both hydrology and ecology provide a place to start.
Years ago, hydrologists observed power-law hydraulic-geometry as systematic spatial patterns of flows, velocities, depths, widths, slopes, friction, and sediment flux in channel networks (Leopold and Miller, 1956), and temporal patterns at given locations (Leopold, Wolman and Miller, 1964, p. 216). Some of these observations have served as an inspiration for developing new theories of channel networks (Rodriguez-Iturbe and Rinaldo, 1997). Systematic patterns also exist in residence-time distributions for subsurface flow and transport. Specific relationships in the form of the power laws reflect invariance with respect to scale change, yet they can change with climate and other local attributes (Gupta and Waymire, 1998). Observed patterns suggest the possibility of pursuing an understanding of scaling that combines observations and theories from meteorology, hydrology, and geomorphology in drainage networks to quantify unmeasured dimensions, storages, and fluxes, and this concept provides a promising starting point for framing a Natural Laboratory.
- What scaling relationships describe observed patterns of stream geometry? Observed topography? Observed flows?
- How do hillslope processes partition basin response among flows with different residence times?
- Can these scaling relationships be explained by a general physical-statistical theory? How can we derive averaged relationships or diagnostic laws at different scales?
- What degree of reliability using scaling relationships to aggregate and disaggregate fluxes in drainage basins can be attained?
- How can such relationships be used to gain understanding of the roles of soils and geology in predicting ground water discharge?
Filling Data Gaps
Major gaps in existing data sets must be covered to investigate spatial scaling issues. One recent study took data at 300 locations to investigate scaling relationships in hydraulic-geometric variables as functions of stream discharge on a 150 sq. km river basin in New Zealand (Ibbitt et al., 1998); however, the numbers are still "hit or miss." Additional study is needed to determine the limitations to what can be achieved with data currently available from remote sensing, what additions to that data set might reasonably be made, and a reasonable density and locations for complementary surface gages. The primary needs are to improve water balances and scaling relationships.
The logical approach would be to collect consistent data sets from hillslopes in upland, transition and valley areas over a river basin to establish space-time distributed water balances. The key data are precipitation, evapotranspiration, surface and subsurface discharges and surface and ground water storages. One approach to data collection would be to use "physically-based filters" to estimate surface and subsurface runoff generation and transport across networks at fast and slow time scales. As the method is refined, scaling methods can be used to estimate flows at ungaged locations; and these flows can be used to estimate integrated-dynamic-storages of moisture in unsaturated and saturated components of hillslopes. A second approach would be to estimate evapotranspiration and related fluxes at 250m and 500m resolution using MODIS products (Justice et al. 1998) derived from production efficiency models that estimate soil moisture storage in the rooting zone from an association between air temperature, spectral vegetation index, and biomass. These tools can eventually establish spatially distributed water balances over drainage networks.
Progress of the science will depend on the uncertainty structure in estimates of soil moisture, precipitation, and evapotranspiration. Quantification of uncertainty requires intensive, sustained, and coordinated measurements at a rate and density sufficient to reveal dynamic water, energy and transport components across multiple scales. Statistical design criteria to assess tradeoffs between cost and scientific contributions can be used to determine sampling points, frequencies, and needs to modify the data collection system. One can see a pattern for natural laboratory development emerging through needs for increasing refinements.
Studies on scaling stream flows and network geometry raise many additional issues. Four categories likely to be useful in scoping and systematizing the growth of WEB science are:
- What scaling relationships describe observed patterns of precipitation? Evapotranspiration?
- Do relationships between time and space scales imply hierarchical and/or self-organizing systems?
- Is there a commonality between scaling in surficial and atmospheric processes? Can information on scaling in precipitation be combined with scaling in river networks?
- How do hillslope processes partition and retain moisture and thereby impact evapotranspiration and energy flux feedbacks?
- How do processes operating at a planetary spatial scale and much longer time scales affect basin-scale water and energy fluxes? What are the impacts of low-frequency climate oscillations?
- How do these large scale processes impact seasonal dynamics? How do the impacts vary among climatic and physiographic regions?
- Is the spatial and temporal scaling of hydrologic fluxes (from hillsides, in streams, and through aquifers) modified by low-frequency hydroclimate dynamics? Can these scaling relationships be used to predict how river flows vary with changes in large-scale climate regimes?
- How do surficial relationships integrate over time into spatial patterns in aquifer heterogeneities? How can the knowledge about these patterns be used to depict subsurface flow?
- How do hillslope processes vary with soils and geology? What scaling issues are involved? How does this relate to solute fluxes from drainage networks? To slope stability and sedimentation?
- How can scaling principles be applied to use studies of chemical interactions in stream alluvium to predict solute fluxes at larger scales?
- How does urbanization, other land use change, and waste discharge impact solute fluxes?
- Vegetation is organized in drainage networks by the availability and quality of water, and in turn influences the space-time organization of water fluxes. What spatial and temporal scales from the land surface have important feedbacks on atmospheric structure and dynamics? How can these feedbacks be parameterized and from what data?
- Can a new "physiological" approach be used to organize climate-water-ecological system research and identify emergent space-time structures?
- Can information on scaling in atmospheric and surficial processes be used to predict scaling in ecological statistics? Environmental degradation?
5.1.2 Atmosphere-Related Processes
In the planetary water cycle, water evaporates from ocean and land reservoirs, moves through the atmosphere, precipitates, and is discharged back to the reservoirs through rivers and aquifers. The space-time organizations of precipitation and evapotranspiration are the key components of the planetary water cycle, and these are poorly understood.
- What linkages can be used to derive and validate distributed, stochastic-dynamical models of rainfall variability in space and time?
- How do the space-time distributions of snow cover, soil moisture, and vegetation influence continental heating and modulate precipitation and evaporation? How do these relationships vary with latitude and continents?
- What feedbacks between land and atmosphere dominate at daily, seasonal and longer time scales? How can needed data be measured with remotely sensed and ground observations and used to estimate model parameters?
- How can better understanding of these feedbacks be used to improve connections between global climate and river-basin hydrologic models?
- To what degree does randomness in atmosphere-land interactions constrain forecasting water and energy fluxes?
- How are basin water-energy balances modulated by global climate? At what size do regional surface disturbances begin to influence planetary circulation? How do regional factors influence the dynamics of large-scale atmospheric water fluxes such as the Asian and North American monsoons, the summer low level jet in the U.S., frontal precipitation, and tropical storms?
Filling Data Gaps
The needs of weather forecasting and global climate modeling are driving the collection and organization of atmospheric water data worldwide. Data sets on large-scale water fluxes in the atmosphere and oceans are becoming more available and reliable, but we are a long way from having the information needed to tie hydrologic to ecologic and atmospheric processes. Better coverage and finer resolution for precipitation, evaporation, soil wetness, and land cover, particularly for mountains and deserts, is needed. Data examples include temperature, humidity, wind, turbulent sensible-heat, carbon and nitrogen fluxes within the atmospheric boundary layer, short- and long-wave (infra-red) radiative fluxes; moisture and temperature profiles through the root zone by plant functional type, soil density, heat capacity, conductivity and porosity; and such plant properties as leaf area and reflectance and stomatal conductance. However, hydrologic, atmospheric, and biologic data collections need to be matched by scale within the context of new theories combining scaling, coupling, diagnosing and modeling. For example, methods for measuring groundwater fluxes at larger scales are virtually non-existent. Similarly, innovative ground-based and remotely-sensed instrumentation are needed to better quantify cloud cover. Obviously, we face significant challenges in prioritizing efforts to add measurements and in structuring data collection across disparate space and time scales. A Natural Laboratory would address these questions systematically.
A great deal has been learned from field campaigns devoted to land-atmosphere interactions (FIFE-86, -89, STORM-FEST, CASES-97, -99, ABLE, and SGP-97). FIFE and STORM-FEST indicated that a distance of at least 60 km is needed to estimate advection in the atmospheric water budget. A corresponding dimension for water balance in a river basin would require areas of the order of 4,000 sq. km. or larger. The priorities for adding measurements should be based on service to science. A good place to start would be to quantify advective moisture fluxes in and out of a river basin by collecting and organizing data on large-scale atmospheric divergence and convergence as well as moisture fluxes. Currently information is inferred as gridded-state variables from climate models working from sparse upper atmosphere data somewhat augmented by surface temperature and convection surrogates. Data additions could be based on expected gains to interpretation and understanding. For defining these, a Natural Laboratory can make diagnostic analyses of data contributions to models applied to address specific science questions. Such studies would suggest durations of observations and how to balance collections of remotely-sensed and ground-based data.
One type of data expected to emerge is on the role of evapotranspiration in reducing energy available for surface heating and in causing turbulence in the atmospheric boundary layer. The altered vapor pressure deficits also reduce soil evaporation and influence stomatal control of transpiration. Evaporation reduces surface heating as water vapor condenses into clouds.
- How do land-atmosphere feedbacks impact temporal evolution of low frequency climate oscillations?
- How are regional-scale water and energy fluxes modified during planetary climate oscillations?
- How does the partitioning between runoff and infiltration with subsequent baseflow relate to long-term trends in river and aquifer water quality?
- How can scaling be used to improve integration of land-atmosphere processes to determine impacts of natural cycles and human-induced change on water quality?
- How does the mix of (diversity in) vegetation respond to changes in climate and basin land use and influence local water and energy budgets and landform evolution?
- How would changes in land use and vegetation impact river flow to the ocean and hence regional and planetary climate
- How does microclimate interact with hillslope characteristics to determine ecologic patterns?
5.1.3 Climate-Related Processes
The Earth system exhibits quasi-oscillatory climate patterns at seasonal to millennial time scales. We need work to understand how land and ocean features and biotic processes organize cloud cover and atmospheric water vapor transport through intermittent "tropospheric rivers" from sources of convection to zones of landfall (Newell et al, 1992; Mo and Higgins, 1998). Studies into long-distance correlations in hydrologic processes (teleconnections) have shown that ENSO events in the tropical Pacific can have major impacts on precipitation and temperature in the Western United States. Likewise, winter teleconnections to higher latitudes may alter planetary wind circulation and storm tracks. Gray (1992) has shown a modulation of Atlantic hurricane frequency by continental soil moisture, vegetation and surface heating. Chase et al. (1999) showed that land use change in the tropics alters partitioning between sensible and latent heat fluxes and hence thunderstorm patterns. Through understanding the forces driving these patterns, we become better able to deal with resulting hydrologic fluxes, landform changes, ecological impacts, and environmental risks.
A major challenge exists in understanding the role of the water cycle in stabilizing planetary climate by mechanisms which range from the modulation of seasonality by advection to thermostatic regulation of climatic equilibria. Biophysical models that show constant average temperature (homeostasis) under increasing solar luminosity through self-regulation (Lovelock, 1995) suggest that hydrologic and biotic processes over land may be critical in damping teleconnections and hence planetary response to global warming.
Another challenge is in diagnosing regional changes in water fluxes resulting from low-frequency climate oscillations and from teleconnections. The work could probe changes in flood frequency, e.g., American River, CA (NRC, 1999c); high lake stands, e.g., Devils Lake, N. Dakota; the 1930's drought on the Great Plains; and the phenology of high-latitude vegetation and insect populations. Basic advances would enhance long-term predictability of floods and droughts.
- What role does the energetics of water play in modulating planetary climate and thereby reducing risks from changes in the amplitude and frequency of climatic oscillations (large-scale deforestation or desertification)?
- How are high-frequency hydrologic events (extreme floods) modulated by low-frequency climate oscillations, e.g., ENSO?
- How can the monitoring of stream flow, well and lake levels, corals, tree rings, etc. be used as indicators of pending drought? How can they be used to indicate spatial differences, interspersed wet spells, and biological impacts?
- Can we develop a unifying theory on drought evolution at the regional scale? How does surface hydrology change the frequency and amplitude of climatic oscillations?
- To what extent can one discriminate between long memory processes versus secular or oscillatory trends? Are these patterns tied to low-frequency climate oscillations?
Filling Data Gaps
Precipitation, temperatures and atmospheric pressures have been recorded for 100 years over much of the planet, but much less information is available for many key hydrologic and ecologic variables. The major investments in studies on long-term global change research have not produced hydrologic databases comparable to those used in atmospheric studies. Work to extend the limited efforts by the USGS and Lettenmaier et al (1994) would be invaluable. Much would also be gained by developing regionalized estimates of hydrologic fluxes from oceanic and atmospheric 're-analysis' projects by applying physical process models and scaling ideas. Uses of streamflow, ground water levels, and lake levels need to be explored.
Studies into interdecadal and longer variability require very long records, and researchers will have to use paleo-climate proxies such as tree-ring reconstructions (Cook et al, 1999). Longer proxies of hydrologic conditions have been tracked from sediments, isotopic analyses, debris and other sources. There is a need to explore strategy to develop the best multi-century, multi-proxy reconstruction of hydrologic variability (floods as well as droughts). Results could be tested in a split-sample mode against a century-long reconstruction based on systematic hydrologic records. Such a data base could provide a rich basis for exploring issues related to flood scaling, drought and its ecological impacts, atmospheric teleconnections to regional hydrology, and patterns in aquatic chemistry.
As a starting point, NSF and NOAA Paleoclimate research programs support limited development of tree-ring and other climate proxy data sets. Cook et al. (1999) demonstrated the utility of such data in reconstructing regional drought indices and relating them to ENSO and annual streamflow (Meko et al, 1998). This suggests that North American tree-ring and other proxy data bases could contribute significantly to studying river-basin hydrology. For instance, isotopic analyses offers valuable data on the residence-time distribution of water in basins. There may be ways to relate residence-time distributions to river-basin network topology, low-flow characteristics, tree growth, and climate. Statistical investigation is needed to solve the inverse problem of relating tree rings to hydrological fluxes.
- How can one infer future water quality given short records, low-frequency climate variations, and anthropogenic activity?
- What kinds of monitoring can be used to validate and improve modeling in these areas?
- How can one infer future aquatic habitat conditions?
- How are vegetative dynamics impacted by low-frequency changes in water availability and temperature? What vegetative indices are proxies for hydrologic fluxes?
5.1.4 Geochemical Processes
Chemical transport by surface and ground waters varies with the intensity and duration of precipitation, the flow paths available through soils and deeper formations, the chemical reactivity of encountered materials, and the chemical context including redox status and pH. Chemical transformations may either mobilize or deposit contaminants, and the net balance determines ground and surface water qualities in catchments. Important processes affecting, for example, nitrogen and sulfur cycles and erosion and sedimentation in watersheds have been identified, but we do not know how to extend our general understanding to determine impacts of these processes at larger river-basin scales. The U.S. EPA's implementation of the Clean Water Act has come under intense scrutiny, leading to their initiation of more aggressive watershed management. Allowable ?Total Maximum Daily Loads (TMDLs)? are calculated and compared to an ambient water quality standard set to protect specific aquatic habitats or other uses of a water body. Over the next several years, it is likely that thousands of TMDL assessments will be based on extremely limited data. Consequently, there is an urgent need to improve basin-scale water quality information through scientific understanding of mass transport. Research is needed to develop an interlinked water, chemistry, ecology, and landscape data base and innovative process models to resolve questions of attribution on cause and effect of water quality degradation at river basin scales.
- How do hydrologic, biologic, and geochemical mechanisms at small scales affect water quality at the basin scales? Mechanistic water quality simulation models based on small-scale process knowledge are proving unreliable. How can statistical scaling relationships within nested hierarchies of drainage basins be used to improve the aggregation of small-scale processes to larger scales?
- What factors are responsible for changes over time in the chemistry of natural flows at hillslope and then at basin scales?
- How are anthropogenic applications of nitrogen to the land surface impacting the nitrogen cycle in watersheds? What is the role of denitrification as a nitrogen sink in upscaling in subsurface and surface waters? What measurement strategy is needed to monitor denitrification at a watershed scale?
- How can one distinguish long-term natural variations in water quality from human-induced changes? Storm flows may dominate annual contaminant budgets, bypass normal contaminant transformation zones, or cause longer-term shifts in the structure of chemical change.
- Many contaminants (e.g. phosphorous, PCBs) become bound to sediment and deposited in water bodies where they reside for long periods until released by chemical changes or extreme events. How can we predict sequences of sediment generation, transport and deposition through river basins? How can we apply this information to gain better understanding of long-term chemical transport?
- What is the dynamical relation between runoff, erosion, and contamination at hillslope up to drainage-basin scales? How do low-frequency climate variations affect sediment and contaminant movements and residence times in drainage basins?
- How do volatilization, atmospheric transport, and deposition spread contamination and alter land-surface chemistry within and across scales? What are the resulting impacts on runoff and river chemistry?
Filling Data Gaps
The USGS National Water Quality Assessment (NAWQA) Program, the USGS National Stream Quality Accounting Network (NASQAN), and state-level ambient water quality monitoring programs are presently collecting data. These data are being augmented at selected locations and for selected contaminants in small watershed LTER, such as the Coweeta and Hubbard-Brook sites. However, these programs, while important, are largely focused on characterizations and relationships at small scales. The work leaves major gaps in integrating coupled processes at the river-basins scales and in providing information on water quality in ungaged watersheds.
We need measurements to identify and quantify major elemental fluxes between storages within compartments that can support experiments and models to provide insights on processes important at the river-basin scales. For example, human-related activity adds nitrogen from urban and agricultural fertilizers and waste waters. This nitrogen reaches rivers through volatilization and atmospheric deposition and then overland or subsurface flow of nitrogen dissolved or attached to particles, all the time subject to nitrification and denitrification in various ways. Precipitation, wind, and vegetation impact the atmospheric processes. Data on runoff largely comes from small-scale studies that give little insight on processes having large-scale and cross-scale effects. Data collection needs to be expanded to support the development and testing of new methodologies and models. Such a system could then be expanded to the storage and transport of other nutrients, toxics, or to salinity in semi-arid river basins.
As an example of a data collection initiative, a monitoring program could deploy a nested data-collection design in a large river basin. Measurements could cover concurrent stream sediment and chemical (nitrogen, phosphorous, etc.) concentrations (to calculate loads) in water and sediment. Micro-topography (to estimate storage), alluvial chemistry, precipitation, and land use data could be added at a proper spatial resolution. The data base could then be used to explore scaling relationships within a drainage network as climate varies and human activity causes modification. The growing effort to restrain nonpoint-source pollution through "Best Management Practices" that require modifications in land use urgently needs this sort of data and science base.
- Nutrient enrichment of estuaries by human activities contribute to algal growths and blooms (Pfiesteria piscicida) and fish kills. Temperature, salinity, and wind are important forcing functions. While we have a general feel for the causal mechanisms, we understand little about how climate and weather fluctuations and consequent changes in water chemistry stimulate these biological events.
- How are the biogeochemical variables governing water quality linked to stream ecology in river networks?
- What additional scaling relationships must be introduced in going from sediment and nutrient fluxes to ecological impacts? In determining the impacts of biological activity on sediment and chemical routing through river networks?
5.1.5 Ecological Processes
Spatial and temporal scales organize ecological phenomena from metabolic rate to biome formation. Ecologists commonly consider habitat patches and biotic interactions among them at scales smaller than the full network. For example, the dominant theory of ecosystem structure and function used in stream management is based on a longitudinal, non-branching view known as the River Continuum Concept (Vannote et al., 1980; Fisher, 1997). Managers need a science base for adding a network perspective, because network structure strongly influences properties of diverse physiological (West et al., 1997) and ecological systems (Bruns et al. 1984; Fisher, 1997). For example, a network perspective is important for evaluating environmental effects of land-use practices and road networks (Jones et al., 2000).
Network influences on ecological processes can be viewed from several geographic perspectives, and each is suitable for addressing particular classes of phenomena. For example, stream flow generation comes from the full basin, with upland areas supplying overland and subsurface flow and with upstream networks and groundwater storage determining hydrograph shapes and water quality. Canopy shading and reaches with hyporheic (subsurface) flow also influence the thermal properties of stream water. Movements of biota and patterns of debris- flow disturbance and recovery require added geographic perspectives. Different flow characteristics predominate in impacting different ecological systems. Broadly applicable conceptual and modeling systems are needed to develop a spatial mathematical framework within which special types of information can be applied to particular phenomena.
Critical next steps include 1) field studies of various phenomena that influence river network structure, 2) spatially-explicit modeling of these phenomena to explore effects of alternative network structure, and 3) synthesis of a theory of river and riparian network operation from field and modeling studies. This work would identify system factors (e.g., stream flow; energy transfer; water quality; distribution, genetic diversity, and productivity of fish populations) with high or low sensitivity to river network structure and to disturbances.
- How does the network structure of river and riparian systems influence the properties of aquatic and riparian biota and biological processes? This question might be addressed from influences of network structure on fluxes of water, energy, nutrients, pollutants, and sediment, which constrain aquatic biota and biological processes.
- How does the network structure of rivers affect system response to natural and human-imposed disturbances? The network structure creates conditions of vulnerability or of resistance to watershed disturbance. Linear structure makes river networks susceptible to "fragmentation" where dams and other regulating structures modify movements of materials and biota (Dynesius and Nilsson, 1994). On the other hand, numerous small tributary streams may buffer disturbances from debris flows and other causes.
- How do temporal and spatial patterns of streamflow (e.g., relations expressed in water balance, peak and low flows) constrain patterns of biotic populations, communities, and processes in river networks? Is it possible to link scaling relations between hydrologic and biotic systems in the context of hierarchical, branching networks?
- How do surface water-ground water exchanges in the riparian zone impact biological activity at the basin scale? How do factors that determine the spatial and temporal distributions of base flow and of contaminant concentrations affect aquatic life?
Filling Data Gaps
Stream ecology and aquatic habitat are very sensitive to in-stream velocity distributions, topography and exposure at fine scales. While much relevant data exist at isolated sites, they have not been assimilated into a coherent and accessible form to infer the important influences of network structure and channel hydraulic geometry on river ecology. New data that specifically target network properties, e.g., fluxes of water, energy, chemical constituents (i.e., nutrients, pollutants) through networks, and interactions of the river network with biological processes and communities, are needed. Integration at larger scales and across scientific disciplines will require added coordination. Using the previous examples, studies of terrestrial ecosystem-atmosphere interactions using flux towers, which are commonly sited in flat terrain, would need to include complex terrain and topographic and geologic features to be relevant to a wide range of natural watersheds. Focus on integration of understanding of WEB phenomena over small to mid-sized (e.g., 5K-50K km2) drainage basins can be most effective in the context of a natural laboratory based on an interdisciplinary, inter-institutional team working over the long term (decades) using diverse and complementary tools.
5.2 Education on Drainage Networks
Progress in developing WEB science will require graduate students educated with a much broader perspective of the total WEB domain than what exists at present. Sustained funding will require a general public better educated in water and related environmental considerations.
5.2.1 Graduate and Undergraduate Education
Water-related academic programs are often fragmented across such departments as Geology, Geography, Civil and Environmental Engineering, Soil Science and Agricultural Engineering, Biology, and Meteorology. Each discipline has a distinct academic culture that changes slowly and seldom incorporates WEB principles. There is consequently a need for education covering a holistic WEB perspective on environmental problems. Here, a Natural Laboratory would have the role of demonstrating field truths. We provide two examples.
Graduate programs that cut across traditional themes are increasingly in vogue as disciplinary limitations become evident to faculty and students. To give such degree programs a WEB context, a few interdisciplinary courses comprising a "core curriculum" are needed. The core curriculum should introduce the mathematical and scientific foundations underlying key research challenges, and courses should be prepared with WEB-based instruction materials to facilitate their widespread adoption. The Natural Laboratories would play the crucial role of serving as virtual learning facilities with on-line field trips, interviews with scientists, information on research campaigns, and easy access to data and models for hands-on learning. The core curriculum can be implemented successfully by integrating it with existing degree programs in different academic departments on each campus through offering a 'certificate in WEB'. A certificate-mechanism can be viewed as enhancing the scope of existing academic departments with a minimum of bureaucracy, because it is not a degree program and it does not compete for resources with existing departments.
WEB concepts have much to contribute at the undergraduate level. A core curriculum can be developed through a 'group effort' by a small set of universities. A mechanism would be necessary to get input from the larger academic community into the development of the core curriculum so that it can be widely adopted. Such a mechanism can be facilitated by special sessions at professional societies, such as AGU, AMS, GSA, ASCE, ASLO and others, and through workshops.
Both at the graduate and the undergraduate level, there is a critical need to provide real-world, field-based, hands-on experiences in integrative WEB science. Over the last several decades, field experience at the graduate level has severely declined in hydrology; see Serafin et al. (1991) for a discussion in the context of meteorology and oceanography. Major fundamental advances in WEB science can be expected only if students learn to combine field observations with analytical theories. Similarly, ideas from WEB science can show undergraduates the roles of mathematics, physics, chemistry, biology, geology, fluid mechanics and engineering to current water and environmental issues. Specific ideas for achieving this goal are: (i) summer workshops to showcase methods for delivering field experience, (ii) engaging undergraduates in research facilitated by a national hydrologic facility, and (iii) utilizing the internet to transfer information and to facilitate broader supervision of undergraduate and graduate students.
5.2.2 K-12 School Education
The National Hydrologic Facility can greatly enhance the scope and impact of WEB education at the K-12 level. Teachers need integrative hydrologic, biologic and Earth science instructional materials in a format they can use to create personalized curriculum as is being done in Utah (www.surweb.org). The Natural Laboratory Facility will become a primary resource for outreach to education, including the leveraging of resources and opportunities for relating to ongoing hydrological science.
Field studies of hydrologic systems face major logistical and systemic constraints, but WEB can greatly expand and enhance a students' learning experience. For example, a middle school teacher at John Evans Junior High School in Greeley, Colorado, constructed a small-scale version of a river basin in the school yard. A wealth of learning activities has developed around the miniature watershed model that weaves together hard sciences, mathematics, geography and a host of social studies, including a unit on flood insurance, which culminates in a flood simulation. Other hands-on hydrologic education programs include the NSF-funded GLOBE program's hydrological protocols (http://www.globe.gov/) and a variety of River Watch or Streamwalk programs (http://wildlife.state.co.us/riverwatch/) that provide opportunities for integrating abstract knowledge and content within a real-life context.
5.2.3 A WEB-Science for the Public
In democratic societies, informed participation in the critical decision-making process requires an educated and informed citizenry. In recent years, several efforts have been initiated related to water in the environment. For example, the Colorado Division of Wildlife's River Watch program has been successful in developing a culture of "quality assurance and quality control (QA/QC)" responsibility. It serves as a model for how students and citizens can be engaged in monitoring water quality parameters and collecting high-quality baseline data of their local waterways. The Colorado River Watch program has served as an inspiration for the NSF-funded GLOBE program. It provides a means and method for informing and engaging the community in the protection and ultimately the restoration of the environmental systems. In addition to developing a sense of stewardship, such efforts serve as a bridge for understanding and appreciation between schools and communities, between the domains of scientific research and education, and between citizens and their local environment. The EPA-funded Stream-walk program in the Pacific Northwest, for example, provides opportunities to guide "the participant in understanding what can be learned from looking at a stream." (Handley, 1993, p.323). Another example is the EPA-funded Boulder Area Sustainability Information Network (BASIN) project (http://www.basin.org). A Natural Laboratory and a National Hydrologic facility would go beyond the local to provide a nation-wide educational resource to educate the public about the water cycle and its many roles in maintaining our planetary environment and its habitability.
6.0 WEB INFRASTRUCTURE
In Section 4, we gave an overview of challenges to integrated WEB research and the imperative for data-base expansion and integration. In Section 5, we described how WEB research might be built in the river basin context. We propose moving ahead by establishing Natural Laboratories and a National Hydrologic Facility to organize and analyze comprehensive data sets, both existing and new. We are seeking an administrative mechanism to facilitate the deployment of instrumentation; coordinate data collection, archiving, and access for integrative large-scale research; and facilitate education and technology transfer.
A multi-stage approach is necessary to develop infrastructure over time. The procedures will take continuing discussion, and we set forth here a strawman to get thinking going. Our idea is for Phase-I to be a Pilot Project focused on a science theme at the river-basin scale. Simultaneously, a WEB Office for Science Support (WOSS) would be established to reach out to additional themes and to facilitate mechanisms for cross coordination. Some generic issues related to the selection and management of a network of Natural Laboratories are described in Sections 6.1 and 6.2. A brief description of Phase-II is given in Section 6.3.
6.1. Choosing Candidate Natural Laboratories
Given the scope and scale of WEB science and its potential impact on the future of Hydrologic Science, consensus is important. One beginning would be to use the NSF competitive proposal system to select Pilot Project(s). A Pilot Project for a Natural Laboratory should build from: a) an existing array of hydrologic and meteorological instrumentation; b) sufficient available data on soils, geology, ecology, topography from remote sensing and other sources to initiate WEB; and c) creative conceptualization of a strategy for resolving important WEB issues.
Several opportunities exist for using an instrument array to advance WEB science. At NSF, the existing LTER system and emerging programs, e.g., NEON and EARTHSCOPE, provide attractive candidates. LTERs have ecologic instrumentation and data-gathering protocols, but may be too small in spatial scales and be inadequately instrumented for meaningful atmospheric and hydrologic investigations. NEON and EARTHSCOPE are in the early stages of development and offer valuable opportunities for interdisciplinary cooperation in efforts far too large to fund from any program or for any one use. Watersheds instrumented by other agencies may have basic hydrologic instrumentation but not sufficient coverage for integrative WEB science in terms of ecologic, geologic, weather and climate data (e.g., WSR-88D precipitation radar).
One example on how to bring interdisciplinary measurements together is found in the Cooperative Atmospheric-Surface Exchange Studies Project (CASES) at the Walnut River Watershed near Wichita, Kansas. It currently has atmospheric instrumentation (wind/temperature profilers, surface flux stations, soil moisture measurements, rain gauges, low-level aircraft tracks) and is "seen" by three WSR-88D precipitation radars at varying ranges, the closest being at Wichita about 60 km to the west. USGS and Corps of Engineers maintain hydrologic measurements. The Agricultural Research Service has gathered detailed land-use information, but there are no known ecosystems science instrumentation or databases there. More information can be found at the CASES web site (http://www.joss.ucar.edu/cases).
Many other locations are attractive. NSF has funded a new Science and Technology Center, SAHARA, headquartered at the University of Arizona. It is a multi-disciplinary, multi-university, multi-agency effort focused on integrated water-cycle science and assessment. Studies focus on the Rio Grande River in Colorado and New Mexico and the San Pedro River in Mexico and Arizona. Another plausible site may also be found in the Susquehanna River Basin, where Penn State University carried out a 5-year experiment (SRBX-Susquehanna River Basin Experiment) for coupling atmospheric with hydrologic models for flood forecasting.
Natural Laboratories will eventually be needed in more river basins and also to gather data on variations among them as well as at such other systems (bio-habitats) as wetlands, rain forests, lakes, and aquifers. The process must be open to justified ideas for expanding the science. A WEB-Science-driven competition would have no difficulty in finding good candidates.
6.2 Laboratory Management
Many science and management issues will arise in establishing Natural Laboratories and WOSS. The following topics briefly describe some important management issues. Potential strategies for dealing with them follow in Section 7.
6.2.1 Science Steering Group
Mature scientific oversight is essential and could be provided by a science steering group (SSG). Members could come from Natural Laboratories selected through a science-driven competition, impartial scientists with world-class reputations, and representatives from participating federal agencies. The SSG needs balance among experienced field scientists, modelers, and theoreticians from each WEB discipline. This group would advise on priorities and mechanisms for using Natural Laboratories and WOSS to implement WEB science.
6.2.2 Instrumentation Deployment
WOSS would facilitate the deployment and maintenance of field instruments that serve crucial WEB needs and where difficulty in placement is causing a major barrier to scientific progress. Possibilities include standard, calibrated instruments that achieve required reliability in measuring river-stages and soil temperature and moisture as well as piezometers and fluorimeters, to name a few. Standardization in nomenclature, and documentation is essential for coherent investigations meshing with larger scales.
6.2.3. Data Management
One goal of WOSS would be to facilitate access to critical, high-quality, ancillary data from remote sensing instruments that are currently expensive or difficult to use in large-scale hydrologic studies, e.g., digital terrain maps, ground-penetrating radar maps of the water table, and precipitation fields from upward-looking radar. A second goal would be to facilitate easy and low-cost access to essential data collected for other purposes by other agencies, e.g., large fields of WSR-88D rainfall data, multi-spectral data and products from satellites, such as MODIS, on vegetation type and density. A third goal would be to integrate with data collections through the programs of other disciplines (particularly NEON and EARTHSCOPE) and single-investigator projects.
Two basic types of data would be accumulated: long-term and episodic. Data quality control should be the responsibility of the local Natural Laboratory. During investigations of episodic events the local laboratory should maintain the data on the internet, but the final data sets should be transferred to WOSS for long-term management. It is important that eventually all data obtained from the network should reside at a central location managed by WOSS. These data represent a substantial financial and scientific investment and should be preserved. Browser-based visualization software should be available to help scientists identify data sets of interest to them.
6.2.4 Educational Challenges
A team of investigators should be funded to develop a core curriculum, as described in Section 5.2, that integrates use of data sets from Natural Laboratories. In addition, the Pilot Project could facilitate small projects involving educational outreach programs at local universities, community colleges, high schools, and middle schools near a Natural Laboratory.
6.2.5 Technology Transfer
WEB must have an outreach to address societal needs, and this cannot be left to chance. Thought needs to be given to constituting and supporting an effective Technology Transfer team that would interact with the Natural laboratories to facilitate implementation of innovative ideas in the service of societal needs. By working closely with the PIs of Natural Laboratories as well as targeted users (project operators, watershed management organizations, flood and weather forecasters), the outreach program would expedite applications of new findings.
6.3 A National Hydrology Facility
After experience has been gained with the Pilot Project, WEB can move to Phase II. Here, we can think about a National Hydrologic Facility run by a University Corporation, like the University Corporation for Atmospheric Research (UCAR), dedicated to facilitating large-scale interdisciplinary research in WEB. Units or divisions could be housed on different campuses with a strong WEB-Science research and education effort. Each unit would fulfill a specific scientific or educational need such as: (1) hydrologic instrumentation calibration and maintenance; (2) data procurement, processing, archiving and distribution; (3) education support; (4) technology transfer; and (5) international coordination.
- Natural Laboratories to obtain data sets that can be used to address a broad range of WEB-Science topics.
- A WEB Office for Scientific Support (WOSS) to facilitate selection of Natural Laboratories for deployment and maintenance of instrumentation, storage and maintenance of data sets; and to provide coordination among the Natural Laboratories.
- Initiation of a WEB-Core Curriculum development and its implementation.
- Initiation of Technology Transfer utilizing WEB research and data bases.
- Reaching out to the multiple agencies and programs at all levels of government and in the private sector in the United States and internationally to nurture development of WEB science.
7.1 Implementation Strategies
WEB will need to be implemented in stages. We suggest beginning with a Pilot Project. The results could then be assessed after 5 years in a process that would involve the WEB community, research sponsors, and users of the findings. Satisfactory progress would be a signal to establish a National Hydrology facility, but it is premature to speculate how this might evolve.
Two broad approaches to implementation of the Pilot Project can be considered. The first would be based on proposals and the second would use focused management.
7.1.1 The Proposal (Bottom-up) Approach
The use of proposals assumes that quality proposals addressing the issues related to facilitating consistent collection and organization of compatible data in their use in cross-scale studies will emerge, somewhat like the self-organization from complex interactions. Here, the steps would be:
- A call for proposals to select a few Natural Laboratories following guidelines presented in this document and refined by NSF and other participating agencies.
- Establishment of WOSS (using the expertise in the Working Group writing this report and elsewhere) to serve as a coordinating arm by following appropriate mechanisms.
- Interaction with NEON, EARTHSCOPE, LTER, IRIS, and researchers in USFS, ARS, USGS, and other federal agencies as appropriate to support the science being proposed.
7.1.2 The Focused Management (Top-Down) Approach
The top-down approach would give more responsibility to WOSS to create a management structure to insure quality results. This approach would consist of the following steps:
- Appoint a small group of experienced field managers, observational scientists, and modeling/theoretical scientists to define the science and select Natural Laboratories candidates.
- Conduct national meetings to unite the various WEB communities in selecting Natural Laboratories to implement. Use could be made of an annual meeting of a scientific society with broad membership and/or an Internet referendum.
- Support the Pilot Project through the relevant NSF Divisions.
7.2 Selection Criteria
The Pilot Projects would be selected to achieve WEB criteria. The purpose of the Natural Laboratories would be to organize to take systematic advantage of rapidly advancing technologies for obtaining and using data in the development of innovative models and theories. The operating mode would be to test specific hypotheses, which have broad applicability for integrating water, Earth and biological themes. The Natural Laboratories would thus facilitate collection and storage of new data sets, which can be used to advance a basic quantitative understanding of the complexity underlying WEB science.
The success of WEB requires that multi-institutional and multi-investigator teams dedicated to integrated understanding of the hydrologic cycle submit compelling scientific proposals that demonstrate:
- Intellectual contribution to WEB science and broad societal impacts. What expertise would each of the PIs bring to the natural laboratory team? How would the range of expertise be synthesized to address the problems identified for study?
- Innovative theoretical and modeling/simulation studies that would contribute to making these impacts. What expertise does the team have to make these studies?
- A site selection supported by well-reasoned rationale.
- Data already being collected that can be used to support advances in WEB science. What is the prognosis for their continued collection?
- Thoughtful presentation of the additional data required to conduct the science. What would be the new instrumentation and sampling strategies? What data integration plan is proposed? What would be the role of data in testing specific scientific hypotheses? What opportunities are seen for the data contributing to a broader science base that can be used to test additional hypotheses and build WEB science over time?
- Innovative interdisciplinary educational opportunities.
- Support from Federal and state agencies to complement the studies with data or analyses. Will they supply scientists as part of the study team?
These seven criteria will need to be refined as experience is gained in working toward WEB goals. Details will be site- and problem-specific and need to be worked out through agreement by participating agencies.
7.3 Establishing WOSS
The success of WOSS will depend on sound organization within the agencies as well as within the science communities. The office would provide oversight and coordination in working with the PIs in a mode of operation that would evolve through workshops and discussions. A WOSS proposal should be developed and evaluated.
WEB seeks integrative, multiscale understanding of how the hydrologic cycle links physical, chemical, and biological processes in the entire Earth system and evolves over long periods of time. Continuing support and cooperation are necessary to nurture the development of WEB science with funding for instrumentation, management, and maintenance of Natural Laboratories, and multi-investigator, multi-university experiments and analyses. A distributed project structure is destined to foster widespread participation and major advances at the interface of hydrologic, atmospheric, oceanic, ecological and earth sciences.
8. CONTRIBUTORS AND ACKNOWLEDGMENTS
We gratefully acknowledge the many written and verbal comments that shaped WEB over two years. The list of contributors is given below. All the comments we received influenced the evolution of this document even though few specific contributions appear directly. This text had to be greatly shortened to present the consensus case in a document of reasonable length. As WEB develops over time, the need for additional diversity of concepts and methods will evolve, and many more people must become involved. This initiative was funded by a grant from NSF to the University of Colorado, Boulder.
8.2. Written Contributions before the Albuquerque
Geoff Austin, Rabi Bhattacharya, George Hornberger, Lee Klinger, Upmanu Lall, Diane McKnight, Cynthia Nevison, Hari Rajaram, Gary Sposito, Kosta Georgakakos, Vic Baker, Dan Cayan, Claire Welty
8.3. Comments on initial paper before the Albuquerque
Roger Bales, Kenneth E Bencala, Paul Bierman, Wilfred Brutsaert, Stephen Charles, Dave Dawdy, Mike Dettinger, Chris Duffy, Pete Eagleson, Ted Engman, Jeremy Fein, Efi Foufoula-Georgiou, Graham Harris, Ted Hullar, Doug James (response to Ken Bencala), Vit Klemes, Luna Leopold, David C. Goodrich, Witold F. Krajewski, Mary C. Hill, Jeff McDonnell, Roger Pielke Jr., Roger Pielke Sr., Harry Pavlopoulos, Ken Potter, Raymond Schmitt, Jim Shuttleworth, Richard Somerville, Fred Swanson, Kevin Trenberth, Brent Troutman, Scott Tyler, Robert Weller, Ross Woods
8.4. Albuquerque workshop participants (Jan.
Victor Baker, Bernie Bauer, Dan Cayan, Cliff Dahm, Clint Dawson, Chris Duffy, Tom Dunne, Tony England, Dara Enthekhabi, Kosta Georgakakos, Judith Hannah, Mary Hill, Ted Hullar, Stacy Howington, Doug James, Levent Kavvas, Lee Klinger, Upmanu Lall, Ian MacGregor, Diane McKnight, Priscilla Nelson, Fred Phillips, Roger Pielke Sr., Dan Rothman, Gene Rasmussen, J. Dungan Smith, Fred J. Swanson, Charles Slaughter, David Simpson, Irene Sanders, Pam Stephens, Laura Toran, Brian Wagner, Ed Waymire, Claire Welty, John Wilson
8.5. Written Contributions after the
Vic Baker, Boise Hydrophysical Research Group, Phil Carpenter, Dan Cayan, Cliff Dahm, Ted Hullar, Tom Johnson, Vivek Kapoor, Lee Klinger, Jurate Landwehr, Peggy Lemone, Diane McKnight, Dennis Ojima, Fred Phillips, Jorge Ramirez, Pepe Salas, J. Dungan Smith, Laura Toran, Scott Tyler, Gary Sposito, Robert Ward, Chunmiao Zheng
8.6 Program Staff at the National Science Foundation
Doug James, Ian MacGregor, Bob Corell, Herman Zimmerman, Dan Weill, Penny Firth, Berny Bower, Priscilla Nelson, Pam Stephens, Mike Steuerwalt, Keith Crank, William Chang, Wyn Jennings.
8.7 Support Staff at the University of Colorado and Colorado State
Julie McKie, Tammy Palmer, University of Colorado; Shirley Miller, Cat Shrier, Emily Hall, Colorado State University
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ABLE Argonne Boundary Layer Experiments
AGU American Geophysical Union
AMS American Meteorological Society
ASCE American Society of Civil Engineers
ASLO American Society of Limnology and Oceanography
BASIN Boulder Area Sustainability Information Network
BOREAS Boreal Ecosystem-Atmosphere Study
CASES Cooperative Atmospheric-Surface Exchange Studies
EPA (United States) Environmental Protection Agency
FIFE First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment
GEO Directorate for Geosciences of the National Science Foundation
GEWEX Global Energy and Water Cycle Experiment
GLOBE Global Learning and Observations to Benefit the Environment
GSA Geological Society of America
IRIS Incorporated Research Institutions for Seismology
LTER Long-Term Ecological Research
MODIS Moderate Resolution Imaging Spectrometer
MTBE Methyl Tertiary-Butyl Ether
NASA National Aeronautics and Space Administration
QA/QC Quality Assurance and Quality Control
NASQAN National Stream Quality Accounting Network
NAWQA National Water Quality Assessment
NEON National Ecological Observatory Network
NOAA National Oceanic and Atmospheric Administration
NRC National Research Council
NSF National Science Foundation
OHS Opportunities in Hydrologic Sciences
SAHRA Semi-Arid Hydrology and Riparian Areas
SBRX Susquehanna River Basin Experiment
SRTM Shuttle Radar Topographic Mission
SSG Science Steering Group
STORM-FEST Storm-scale Operational and Research Metorology-First Experiment and Systems Test
USDA United States Department of Agriculture
USGS United States Geological Survey
VEMAP Vegetation/Ecosystem Modeling and Analysis Program
WEB Water cycle interactions with Earth systems and Biota
WOSS WEB Office for Science Support