EVALUATION OF THE EVALUE MODEL FOR ESTIMATING MANNING'S ROUGHNESS IN FURROW IRRIGATION

Manning's roughness coefficient is a key parameter in the design and evaluation of furrow irrigation. Despite its importance, estimation of this parameter in surface irrigation is difficult, particularly in furrow irrigation. In this study, the EVALUE model was used for estimating Manning's roughness coefficient in furrow irrigation. The EVALUE model is based on volume balance and has been developed for estimating Manning's roughness coefficient in surface irrigation. EVALUE estimates both infiltration parameters and Manning's roughness coefficient simultaneously. The main input for the model is depth of flow along the furrow at different times. Evaluation of EVALUE was performed by comparing measured and simulated advance and recession data using SIRMOD software. The estimated values of Manning's roughness coefficient ranged between 0.02 and 0.102. The estimated values of Manning's roughness coefficient by EVALUE were somewhat different from the suggested SCS values, particularly during the first irrigation, but comparable with the results shown by other studies. Copyright (C) 2011 John Wiley & Sons, Ltd.