Precipitation Variability Effects on Modeled Soil Water Deficits

by D. G. Boyer, USD-ARS, Soil and Water Conservation, Research Lab, United States,
C. M. Feldhake, USD-ARS, Soil and Water Conservation, Research Lab, United States,

Document Type: Proceeding Paper

Part of: Watershed Planning and Analysis in Action


Effective management of forages in steep Appalachian pastures requires an understanding of hydrologic and microclimatic processes on the area. This study was conducted to determine the spatial variability of precipitation in a steep watershed and its effects on modeled soil water deficits. The spatial distribution of precipitation within a 1.5 ha area of a 4.25 ha watershed was measured with 64 small-orifice raingages. On the average, a 25 percent difference in precipitation catch, during the growing season, was observed. Depending upon the precipitation used as input, modeled soil water deficits varied by about 20 percent during a dry year. The variation in modeled soil water deficits was negligible during a wet year. The results indicate the importance of considering spatial distribution of precipitation when using a water balance model for making forage management decisions in this steep pasture watershed.

Subject Headings: Soil water | Precipitation | Spatial distribution | Watersheds | Hydrologic models | Water management | Mathematical models | Appalachian

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