Sensitivity of Furrow Irrigation System Cost and Design Variables

Abstract

Considering the minimum cost as the objective, the furrow irrigation system design problem is formulated as an optimization problem. A combination of monotonicity analysis, constraint activity, and condensation are used to simplify the size of the mathematical model of the problem. This reduced model is used to analyze the sensitivity of the optimal design variables of a furrow irrigation system. The Soil Conservation Service (SCS) equations for the design of furrow irrigation along with several constraints are considered in the optimal design. Using an example problem and three different soil types, the system cost and design variables (inflow rate, length of furrow, and time of cutoff) are found to be sensitive to the supply flow rate, the design application depth, and the cost coefficients of water, labor, and ditch construction. Under the given set of conditions, the cost of a furrow irrigation system is very high in the case of a clay soil. Also, the application efficiency achieved was lower in the case of a clay soil than in light (sandy) and medium textured soils.