Snow influences the land-surface water budget. Snow measurements are needed both to study climate and to predict drought, flooding, and water availability.
Monitoring changes in vegetation is important for climate and hydrologic modeling applications, validation of satellite estimates of land surface conditions, and testing of ecohydrological hypotheses.
Soil moisture affects the partitioning of precipitation into runoff, evapotranspiration and deep drainage and the fluxes of energy and carbon between the land surface and atmosphere.
Regional water storage loads the surface of the Earth. Changes in loading from these reservoirs becomes evident through vertical displacement time series.