Rangeland areas are characterized by sparse and limited hydrological data that make the use of existing mathematical runoff models difficult and impractical. A simple rational mathematical model was developed to predict runoff in three Oregon semiarid rangeland watersheds, using daily precipitation and mean daily temperaturs. The model consists of three main components to estimate snowmelt runoff due to thawing and rainfall, and rainfall runoff. The model calculates daily flows on a continuous basis. Comparison with measured flows for monthly predictions gave coefficients of determination (R2) varying from 0.67 to 0.81 for different basins and different periods of observation, including verification periods. The predicted timing of monthly flows was consistent with observed data. Using the Curve Number method, new approaches are suggested for snowmelt runoff calculations.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.