Calculation of Field Manning’s Roughness Coefficient

Manning’s roughness coefficient is one of the most important parameters for describing water flow over the ground. However, it is not well established how to determine this roughness parameter in a particular field situation of surface irrigation. In this paper, a method for calculating Manning’s roughness coefficient is presented, based on an analytical model for border irrigation and solved by iteration. The results are satisfied via testing with the field data obtained from different regions and various soil types and situation of field surface.