Modelling of rainfall and runoff using HEC-HMS in Oghani Micro-watershed of Azamgarh District Uttar Pradesh

Abstract

The present study was conducted using HEC-HMS, based on the SCS Curve Number method, Muskinghum method and Unit Hydrograph method, with the primary objective of developing a hydrological simulation model to forecast rainfall and runoff in the Oghani micro-watershed of Azamgarh district of Uttar Pradesh. Ten years rainfall-runoff peak events were used for this study purpose. Out of these ten events six events were selected for calibration and the rest of four events were used for validation. An initial calibration parameter was extracted from the data using geomorphological characteristics. The final parameter of validation was obtained from the optimization methodology and called the model's global values. For these rainfall-runoff events, the total surface runoff hydrograph was computed using the SCS unit hydrograph method that was compared with the hydrographs observed. For these rainfall-runoff occurrences, the cumulative surface runoff hydrograph was determined using the SCS unit hydrograph system that was correlated with the hydrographs observed. Error functions were measured using HEC-HMS for expected values and associations were also determined between observed and predicted values. Error functions include root mean square error (RMSE), mean absolute relative error (RMSE), and mean absolute relative error (MARE). The HEC-HMS model used for rainfall-runoff simulation in the selected watershed shows various errors within the permissible limits (RMSE -1.47, MARE - 0.0035, RMSE - 1.965 and MARE - 0.00595) which indicates the satisfactory performance of HEC-HMS model in predicting runoff. Comparison of the computed peak runoff discharge with measured values shows good result despite limited data availability.