A Runoff Model for Small Watersheds in the Semi-Arid Tropics

ABSTRACT Amodified Soil Conservation Service (SCS) runoff model and a soil moisture accounting procedure were used to simulate runoff for small watersheds. The validity of the model and the moisture accounting procedure were tested using hydrological data collected from small Vertisol watersheds at ICRISAT Center in India. The agreement between measured and simulated daily, monthly, and annual runoff was good. The root mean square error values between the measured and simulated annual, monthly, and daily runoff from a Vertisol watershed were 5.2, 3.1, and 1.6 mm, respectively. The modified model and the moisture accounting procedure simulated quite accurately runoff for high, low as well as normal rainfall years in the semi-arid environment..