Mathematical model for sediment yield in agricultural watershed

Abstract

. The knowledge of temporal distribution of sediment yield is required in the design and operation of soil and water conservation programmes on watershed basis. For the project planning purposes, the estimates made are mostly based on experience. Such estimates are very approximate and grossly inadequate for engineering analysis. Therefore there is an urgent need for , rational analysis of erosion data from catchments, inorder to obtain relationship for erosion rate. Therefore a mathematical daily sediment yield model is developed for Thuthapuzha drainage basin (940 km2 ) of Bharathapuzha basin, corresponding to Muskingum routing equation. The model is based on combined approach of translation and routing for simulating sediment graphs. Thirty seven selected storm events of the drainage basin observed during 1986- 92 are used for estimation of model parameters by Lagrange multipliers method and three storm events of 1993 are used for verification of the model. The model is used to compute temporal distribution of suspended sediment yield on storm basis and their performance is evaluated both qualitatively and quantitatively. Mathematical relationships of mobilized ~ sediment with effective rainfall; computed sediment flow rates with observed sediment flow rates and observed and computed sediment flow with effective rainfall and mobilized sediment were also established. The Correlation Coefficient of all those equations are found to be close to one. The statistical measures of Percentage Absolute Error in peak sediment flow rates, Absolute Prediction Error, Integral Square Error, Correlation Coefficient and Coefficient of Efficiency of the model are obtained as 3.9934, 9.0007, 5.3286, 0.9951 and 0.9659 respectively. The study reveals that the developed model is a very effective tool in the real time forecasting of sediment yield in Thuthapuzha drainage basin.