EXPERIMENTAL INVESTIGATIONS FOR RAINFALL RUNOFF ANALYSIS

Abstract

In this study, experimental investigation of rainfall runoff process is undertaken by combining controlled laboratory experiments with the numerical model. The laboratory experimental work investigates the effect of variation of rainfall intensity and surface slope on the overland flow hydrograph. Twelve experiments were conducted using Advanced Hydrologic System, by generating rainfall on an overland flow plane of sand having a grain size of 0.5 mm to 1 mm. The generated experimental data were simulated using a one-dimensional finite difference numerical model of kinematic wave equation for overland flow. Comparison of observed and simulated runoff hydrograph reveals that the developed KW model simulated well rising, steady state line and upper part of recession hydrograph reasonably well. Study further reveals that the resistance due to flow decrease linearly with increase in slope for a given rainfall intensity. Also for a given slope of overland flow plane, the resistance to flow decreases with increase in rainfall intensity. It was observed that for a given rainfall intensity, an increase in the overland plane slope, reduces the time to peak