HR: 10:50h
AN: H12E-02    [Abstracts]
TI: Event to Multi-decadal Persistence in Spatial Rainfall and Rainfall and Runoff as a Function of Spatial and Temporal Scales
AU: * Goodrich, D
EM: Dave.Goodrich@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Unkrich, C
EM: Carl.Unkrich@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Keefer, T
EM: Tim.Keefer@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Nichols, M
EM: Mary.Nichols@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Stone, J
EM: Jeff.Stone@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Levick, L
EM: Lainie.Levick@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AU: Scott, R
EM: Russ.Scott@ars.usda.gov
AF: USDA-ARS, Southwest Watershed Research Center, Tucson, AZ 85719, United States
AB: Spatial and temporal rainfall variability over watershed scales impacts the hydrologic response which in turn affects runoff, agricultural production, and soil water availability. Changes in the precipitation regime over decades may contribute to changes in vegetation, water supply and, over longer time scales, landscape evolution and geomorphology. This is especially important in the southwestern US, where urbanization is increasing pressure on limited water supplies. Daily, seasonal and annual precipitation volumes and intensities from the densely gaged network of raingages on the USDA-ARS Walnut Gulch Experimental Watershed (WGEW) are evaluated for multi-decadal trends in amount and intensity over a range of watershed scales (1.5 ha to 150 km2). The influence of teleconnections is tested for local-scale rainfall variability. Rainfall and runoff volume and rate variability are compared over the same spatial scales and over a 40 year period of high-quality runoff observations. The major findings of this study are that spatial variability of precipitation decreases exponentially with time scale; that long-term precipitation trends can be captured with a low spatial resolution; and that runoff from the 150 km2 watershed is not significantly affected by factors other than precipitation. High-resolution modeling studies on the WGEW are also discussed to further understand the processes and scales involved in hydrologic watershed response.
UR: http://www.tucson.ars.ag.gov
DE: 1821 Floods
DE: 1854 Precipitation (3354)
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting