EXPERIMENTAL INVESTIGATION OF OVERLAND FLOW SIMULATION

Abstract

The different experimental runs were conducted on the V- catchment system placed on the Advanced Hydrologic System to obtain runoff hydrograph data. The Approximate Convection — Diffusion (ACD) equation based overland flow model was used for the simulation of these hydrographs. Considering various combinations of flow simulation scenarios, a total of 111 laboratory experiments were conducted on the two types of overland flow and channel flow roughness conditions i.e., acrylic sheet surface and with artificial roughness generated with the help of sand paper pasted on the acrylic sheet V- catchment. These total runs were made corresponding to six rainfall intensity conditions i.e., varying from 54 mm/hr to 84 mm/hr, and with four overland plane slopes conditions i.e., varying from 0.22 % to 1.54 %, for each of the three channel slopes. Overall, it is very clearly seen that the ACD equation based overland flow model is able to reproduce the observed hydrographs closely in many cases with Nash — Sutcliffe efficiency greater than 90 %. But in all the experiments, the recession limb of the observed hydrographs could not be very closely produced due to the prolonged flow of water. The reason behind this behavior could be to surface water tension. Except this error, the experimental set up established in the laboratory reasonably generates overland flow hydrographs which could be reproduced by the overland flow model developed based on the ACD equation, including those cases of diffusion behavior of the V-catchment experimental hydrographs