Minimum cost design of furrow irrigation systems

The furrow irrigation system design problem is cast in an optimization sett ing. A structured problem formulation and a pre-solution analysis procedure is presented. The application of the proposed approach in the detection an d removal of constraint redundancy and inconsistency, as well as complicati ons related to scale problems is demonstrated. Key solution features, such as solution existence and (non)uniqueness, constraint activity at the optim um, as well as properties of monotonocity of the functions used in the prob lem definition are studied. The analysis reduced the problem into a form wh ich is easier to solve. A method-of-multipliers based constrained nonlinear programming (NLP) algorithm is developed for the solution of the minimum c ost furrow irrigation design problem. The NLP model includes a subroutine i nto which the minimum cost design problem is programmed. Solutions of rest problems obtained using the NLP model are in good agreement with those obta ined using the General INteractive Nonlinear Optimizer (GINO) model. The va lidity of the numerical solutions of the test problems is further assessed by comparing them with solution features and properties identified in the p roblem formulation phase.