Laboratorial Investigation of Effect of Plan Shape and Profile Curvature on Variations of Surface Flow In Complex Hillslopes

Hillslope shape is one of the most important parameters that affects the runoff quantity. Determining the effects of this parameter on environmental management and runoff and sediment control is important. Due to the lack of sufficient data and knowledge on these data, most of the structures made for the control of runoff and erosion are not designed properly, mostly overdesigned. A laboratory research is conduced to investigate the relation between profile shape considering the width of the hillslope (divergence, parallel, and convergence) and longitudinal profile of the hillslope (concave, straight, and convex). The Evens geometrical model of the hillslope was made in laboratory that involved the topographical effects of hillslope (i.e. plan shape and concavity of hillslope profile). By considering the three cases of hillslope plan and three cases of profile, nine different shapes were achieved. Varying these parameters in the model, different maximum discharge and time of concentration in the hillslopes would be obtained. Based on the results, plan shape affected the time of concentration more than slope profile, so that the time of concentration in convergent hillslopes is more than divergent hillslopes.