A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1993

An optimization and simulation methodology is adopted for planning the management of an operational command area in dry season to improve the water management of the irrigation project. Linear optimization models of water and land allocation including simulation of the supplemental irrigation canal for wet season performance are presented in this study. Optimal cropping patterns that maximize net benefit for the farmers as well as optimal water allocation in the command area are obtained by the simplex method of the HYPER LINDO package running in a micro computer. Two scenarios of irrigation planning for Plai Chumpol Subproject, Phitsanulok Irrigation Project, Thailand are analyzed. The first scenario, three years rotation plan, is obtained by LP model while the second scenario is the summarized results of the first scenario which are tested by irrigation canal simulation governed by Saint V enant equations for unsteady flow in open channel. These equations are solved by the finite difference scheme and the double sweep technique. Through this, the selected policy is evaluated whether it can be adopted without failure. The strategy in terms of reducing the amount of sown area at downstream end is used in case of insufficient capacity of main canal. The optimal net benefit curves, sown area curves and water allocation curves are obtained from the solutions of the LP model by sensitivity analysis with the variation of some constraints to assist decision makers in the analysis of irrigation planning. The results of the first scenario will be significant as equitable distribution supplies to the farmers while the results of the second scenario will be significant as the improvement of the water use efficiency of the irrigation systems.