COMPUTATION OF RUNOFF FOR SEMI-URBAN WATER-SHED OF ROORKEE UNIVERSITY CAMPUS (WITH PARTICULAR EMPHASIS ON THE EFFECT OF URBANIZATION)

Abstract

Effect of urbanization has a significant role on the outflow runoff as well as other response elements of the hydrologic system. The impervious area in a semi-urban watershed increases with the growth of urbanization reducing the green cover or, other pervious areas. Since the roughness coefficient and infiltration rate of the impervious area significantly changes from green cover area/pervious area to impervious area, the response elements of the system, viz., peak outflow, time of concentration, maximum velocity of flow, and flood persistence period etc. also change accordingly. The present work deals with the computation of runoff for the semi-urban watershed of Roorkee University campus, Roorkee, U.P., India by deriving unit hydrographs of different unit durations. The study on the effect of urbanization an the afore said response elements has been carried out on the basis of the urbanization data (viz, extent of Builtup ground area and pucca road surface area since 1949 at 10 yrs. interval ) available for the University campus. These effects are studied with three different overland roughness coefficients, to account for the variations in the nature of growth of greenery.