Runoff Prediction: Use of Muskingum Model for a Small Watershed

Abstract

An effort was made to develop a mathematical model using unit-step and transfer functions approach for Karkara watershed of Tilaiya dam catchment in Upper Damodar Valley of Jharkhand State of India for estimating direct runoff hydrographs on storm basis. The model used rainfall data in blocks of finite duration represented by unit step function. The outflow hydrograph ordinates were obtained by taking inverse Laplace transform of product of Laplace transforms of the transfer function (Laplace transform of Instantaneous Unit Hydrograph) and the input (effective rainfall). The direct runoff hydrograph ordinates were computed by lagging outflow hydrograph ordinates. Model parameter was estimated by Sabol method using rainfall and runoff data of the study watershed. The model was calibrated for nine storm events, and validated for three events. Quantitative performance of the model was tested using some of the widely used statistical indices as integral squared error, relative squared error and coefficient of efficiency. The estimated direct runoff hydrographs using the model were in close agreement with the observed direct runoff hydrographs. The developed model can be satisfactorily applied for prediction of storm direct runoff hydrographs from small watersheds in the study region.