Two-dimensional hydrodynamic simulation of basin irrigation: analysis of field shape effects on irrigation performance

Abstract

Overland flow of water over a porous bed in two spatial dimensions is governed by three partial differential equations accounting for continuity of momentum in the x and y directions and continuity of mass.

After consideration of several numerical procedures, an explicit finite difference leapfrog numerical procedure was applied to the solution of this system of equations for the initial and boundary conditions that characterize level basin irrigation. The numerical procedure has proven to be stable and robust for many different applications. A design model was developed for use in PC compatible computers. The model implements a user friendly interface and uses three— dimensional graphics to facilitate data analysis. The model is an innovative tool for the design of level basin irrigation systems. Better irrigation system designs at the farm level will improve water management and optimize the use of farm production resources.

The level basin irrigation design model can deal with three different inflow configurations: une, comer, and fan, which simulate inflow from an overflowing canal on a field boundary and at point sources from a comer or in the middle of a straight boundary, respectively. The results of the mnodel have been validated with field data from basin irrigation field evaluations, and the agreement has been satisfactory. The model was used to study the effects of field shape on irrigation performance. The results show that one— dimensional models accurately predict the recession time and efficiency terras of rectangular basins irrigated from a comer, but they underestimate the time of advance by up to 20%, especially if the field width is larger than 40% of the field length.