Multi-Objective Planning Model for Large Scale Irrigation Systems: Method and Application

An increase in demand, and droughts in recent years have resulted in the need for tools to allocate limited water between users in different regions in order to achieve economic, social and environmental benefits. Multi-objective planning is an important decision support tool for natural resource management. Planners, decision makers and stakeholders use this approach in the decision-making process. In this research, a multi-objective planning model was developed and applied on the Menemen Left Bank Irrigation System of the Lower Gediz Basin in Turkey. The aims of the model were to increase the benefit from production, to increase the size of the total area irrigated, and to reduce the water losses occurring at network level. The model was applied to an open channel system consisting of 44 tertiary channels receiving water from three secondaries, serving an area of 3,606 ha. The model predicted a 20.63% increase in income, and a 29.26% decrease in the total irrigation water requirements of crops dependent on projected changes in the actual crop pattern of the research area. This decrease caused a reduction of 29.90% in expected water losses over the network as a whole. The operation of the model enabled optimum productivity and income at the system level per unit of land and water resources.