Simulation of Unsteady Flow in Irrigation Canals with Dry Bed

Abstract

Water losses in irrigation systems are a major problem in arid countries. The losses are primarily due to inefficient irrigation systems and uncontrolled water delivery. Improving the irrigation‐management systems is therefore necessary to conserve the available water. Numerical modeling appears as an important aid in solving this problem because it has been proven to be an excellent tool for designing and simulating flows in irrigation networks. However, shallow‐depth and dry‐bed situations, which are frequently encounted in irrigation canals, are classical problems in computational hydraulics, often causing computational difficulties. Extensive numerical experimentation, supported by analysis of the characteristic behavior of the governing equations, has led to development of new approach for avoiding the singularities of vanishingly small depths in canals. This new approach is based on suppression of the inertial terms in the equations when small depths appear imminent.