ESTIMATION OF MANNING ROUGHNESS COEFFICIENT FOR BASIN AND BORDER IRRIGATION

Selection of a specific surface roughness value in a particular field situation in surface irrigation is not well established. This study was taken up to develop a technique for determination of surface roughness values for basin and border irrigation from irrigation field data. Volume balance analysis, a partial differential form of the continuity equation, and Manning's equation for open channel flow were used as governing equations. The "forward difference approximation" of the "finite difference method" was used as the solution technique. Field data collected from the central farm of Bangladesh Agricultural Research Institute at Joydebpur was used to test the technique. Roughness values derived by this technique were compared with those reported by several investigators. A reasonable good agreement was found between the predicted and reported roughness values. © 1990.