The Impact of Rainfall -Runoff on the Performance of Main Irrigation Canal and Cross Drainage of Omo-Kuraz I and II Sugar Project (The Case of Omo-Gibe Basin)

Abstract

Flood is serious economic losses like damage main irrigation canal and installed infrastructure on sugar project. The objective of this research was to provide an estimation of rainfall-runoff effect on main canal irrigation scheme. The hydrograph characteristics of observed and simulated events are compared using various evaluation criteria consisting of Nash-Sutcliffe coefficient (NSE) is between 0.8 and 0.9, relative volume error (RVE) between -10 and 10%, and coefficient of determination (r2) is between 0.8 and 0.9 during calibration and validation period. Among the catchments of the basin that are used in the regional modeling work and nine Model Parameters are selected among those commonly used in regionalization studies. Four parameter regionalization methods (linear regression, spatial proximity, area ratio and sub-basin mean) were applied to transfer model parameter values from the gauged to the un-gauged catchments except area ratio method. In regional model, gauged catchments Model Parameters and Physical catchment characteristics of un-gauged catchments were used to develop the equations in order to predict discharge of un-gauged catchments. To have better understanding of model parameter performance, the sensitivity analysis of nine model parameters were performed manually by trial and error. The evaluation demonstrations that time of concentration (TC), storage coefficient(R), maximum storage (MS) and constant rate (CR) are more sensitive than others. Therefore, spatial proximity method is recommended in predicting discharge for un-gauged catchments for this research and obtained 85.1m3/s, 1.6m3/s, 9m3/s, 0.6m3/s,1.1m3/s, 14.3m3/s and 28.2m3/s peak flow for cross drainage three, culvert outlet four, culvert outlet three, culvert outlet two, culvert outlet one, cross drainage thirteen and cross drainage fourteen un-gauged sub catchments respectively. To determined predicted peak discharge using L-moment method in flood frequency analysis of selected gauged catchment. Finally, flood damage protection structures like dyke must be recommended for temporary, but redesign depend on peak discharge is necessary. Keywords: HEC-HMS, Regionalization, Stream flow simulation, L-moment, un-gauged catchments, Omo-Gibe sub-basin DOI: 10.7176/CER/14-2-02 Publication date: April 30 th 2022