Characterization of Thunderstorm Rainfall for Hydrologic Modeling

by Herbert B. Osborn, Southwest Watershed Research Cent, Tucson, United States,
David C. Goodrich, Southwest Watershed Research Cent, Tucson, United States,
Carl L. Unkrich, Southwest Watershed Research Cent, Tucson, United States,

Document Type: Proceeding Paper

Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives


Rainfall and runoff records for 30 events from a 630-hectare subwatershed on the USDA-ARS Walnut Gulch Experimental Watershed in southeastern Arizona were used to estimate the desirable spatial resolution of rainfall data required as input to a hydrologic model (KINEROS, Woolhiser, et al., 1990). Runoff peaks and volumes modeled from data at a centrally-located raingage and from a dense 10-gage network were the basis for judging model performance as a function of rainfall representation. In addition, a 100-yr thunderstorm was modeled on three adjacent subwatersheds of different sizes and shapes to explore the relation between the spatial characteristics of watersheds and thunderstorms. For the watersheds examined it was found that if a spatially uniform thunderstorm rainfall assumption is made, significant overestimation of 100-yr runoff volume and peak rate estimates can occur, leading to overdesign of flood protection.

Subject Headings: Hydrologic models | Rainfall-runoff relationships | Storms | Rain water | Watersheds | Runoff | Mathematical models | Hydrologic data | Arizona | United States

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