PHYSIOGRAPHIC INVESTIGATIONS OF MOUNTAINOUS. WATERSHEDS

Abstract

The physiographic parameters especially overland slope and channel slope have been workedout using different methods, considering the system as lumped and distributed for Upper Yamuna Basin upto Lakhwar Dam site. For non-linear modelling the Kinematic Wave model application were tried on to the six sub watersheds ranging from 7 km2 to 305 km2. Open book• type physiographic model with a central drainage channel and two rectangular overland planes, equal in sizes were used for conceptual representation. - As no rainfall and runoff data was available, studies of academic interest were carried out. In the first case, a unit rainfall intensity (lcm/hr) of infinite duration was considered where as in the second case, a unit hydrograph of duration 15 minutes will be obtained fromS-hydrograph for caculation of C. and C (Snyder unit hydrograph parameters). The overland roughnesses were changed and four values of n = 0.25, 0.30, 0.35 and 0.40 were tried. It was found that as roughness increased, the time to peak is also increased. In the general trend., it was observed- as the channel bed slope increased, the value of coefficient Cp starts decreasing. With the increase in the value of overland roughness, the value of C and C generally starts increasing. These conclusion may make significant contributions from the considerations of management of watersheds in the Upper Yamuna Basin and for making.runoff.computations from ungauged areas.