Annual Runoff Estimation for Catchments in India

Estimates of annual runoff are needed for planning of water resources projects. There is a lack of long‐period runoff records in a large number of catchments in India. In the absence of detailed data, use of regional relationships is made for hydrologic planning. Data from 55 non‐snow‐fed catchments in the Indian subcontinent, having an area greater than 347km2, are analyzed to study the influence of selected climatic, topographic, and land‐use variables on the mean annual runoff. The mean annual rainfall, mean annual temperature, and vegetal (forest) cover factor are the most important variables influencing ihe mean annual runoff. The forest cover is positively correlated with mean annual runoff from large catchments. Relationship for the coefficient of variation of annual runoff has also been proposed. Making use of the fact that the annual runoffs follow the normal frequency distribution, one can generate annual runoff series for the required purpose. The results of the present study can be used for pl...