Modification of furrow Manning's roughness coefficient estimation by finite difference technique under surge and continuous flow

Abstract

In this research, the Manning's roughness coefficient under surge and continuous flow was determined based on the volume balance equation in the form of a differential equation that was solved with the six finite difference approximations procedures. Volume balance analysis and Manning's equation for open channel flow were used as governing equations. Six finite difference approximations [forward finite difference (two methods), central finite difference (two methods) and backward finite difference (two methods)] were used as the solution technique. Comparison of the results showed that there is no significant difference between these methods according to average absolute error (AAE) for the 36 datasets. The results of measurements at three different experimental sites indicate that the values of n for continuous flow irrigation were higher than those measured in surge irrigation. The results are satisfied via testing with the field data obtained from different regions and various soil type.