MODELLING OF FLOOD FLOW OF UPPER YAMUNA WATERSHED

Abstract

The Upper Yamuna Basin upto the Lakhwar Dam site has been investigated. The physiographic parameters have been workedout, considering the system as lumped as well as distributed chapter 3.2 and 3.3. From the observed data, unit hydrographs have been derived at the Lakhwar Dam site using Collin's approach, Nash's model and Clark's method (Appendix I ( a) to ICC)). Nash's model produced the better suited unit hydrograph. Synthetic unit hydrographs were developed for the two up-stream sites located at Rai gar h and Kuwa. Unit hydrographs have been utilised to determine the Muskingum routing coefficients (chapter 4.1). For non-linear modelling the Kinematic Wave model application were tried on to the four sub-watersheds ranging 100 km` to 305 km`. Open book type physiographic model with a Central drainage channel and two rectangular overland planes, unequal In sizes were used for conceptual representation. As no short term rainfall and runoff data was available, studies of academic interest were carried out. In the first case, a unit rainfall intensity of infinite duration was considered where as in the second case rainfall excess of 1 cm/hour and of one hour duration was used. The overland roughnesses were changed and five values n = O. 1 , 0.15.0.20.0.25 and 0.30 were tried. It was found that as roughness increased, the time of concentration increased, (Figure 5. 8. to 5.11) peak values (Figure 5.20 to 5.23) and velocities at the outlets decreased (Figure 5.12 to 5.15?,these conclusions may be regarded significant from the considerations of management of watersheds in the Upper Yamuna Basin