HR: 1340h
AN: H33C-1451    [Abstracts]
TI: Is Regional Groundwater Flow a Significant Component of the Water Budget in a River Basin?
AU: * Schaller, M F
EM: schaller@rci.rutgers.edu
AF: Rutgers University Geological Sciences, Wright-Rieman Labs 610 Taylor Road, Piscataway, NJ 08854,
AU: Fan, Y
EM: yingfan@rci.rutgers.edu
AF: Rutgers University Geological Sciences, Wright-Rieman Labs 610 Taylor Road, Piscataway, NJ 08854,
AB: The spatial organization and temporal memory of the groundwater reservoir, and its interaction with the surface water has an integral role in the lateral transport of continental water and energy, affecting soil moisture distributions, evapotranspiration, precipitation and stream discharge across the land surface. The current climate models are unable to account for this lateral component, and route Precipitation (P) minus Evapotranspiration (ET) directly to stream discharge; hence, a separation of groundwater flow from surface water flow is necessary to asses the relative importance of each reservoir across a given continent. Here we use the ratio of P-ET (surface recharge, or R) to stream discharge (Qr) to evaluate the importance of the groundwater component within a given basin; where Qr/R = 1 we surmise that all the atmospheric surplus exits a basin through river discharge; where Qr/R < 1, a basin is considered a groundwater exporter; and where Qr/R > 1, a basin is considered a groundwater importer. In this study, 39 years of USGS HCDN annual mean observed stream discharge (naturalized) from 1555 basins across the continental U.S are removed from total surface recharge, derived from VIC simulation, yielding the portion of surface recharge leaving a basin via subsurface pathways. It was found that the Qr/R ratio deviates significantly from 1 across the contiguous 48 U.S. states. Detailed investigations of individual basins across the continent suggest that deviations of the Qr/R ratio from 1 are primarily a function of the subsurface geology, while climate and basin scale influence the magnitude of those deviations. Further, a marked incongruity between the surface drainage flow direction and groundwater flow direction is apparent where regional groundwater flow has developed, suggesting that surface drainage as a result of elevation is only partially indicative of subsurface flow regimes. This apparent significance of the groundwater component reinforces the need for inclusion of the groundwater reservoir in the current climate models.
DE: 1818 Evapotranspiration
DE: 1830 Groundwater/surface water interaction
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: 2007 Fall Meeting