Integrated Planning of Land Use and Water Allocation on a Watershed Scale Considering Social and Water Quality Issues

Sustainable development in river basins depends on sound management of land use and water allocation policies. Integrated water resources management (IWRM) is considered a path to bring many elements within the development schemes together toward a unified land-water planning and management process. In this study, an integrated water resources management model is developed to connect three groups of decision makers in pollution control, agricultural planning, and water resources allocation with economic, environmental, and social objectives. A genetic algorithm–based optimization model is developed for providing desirable water quality and quantity while maximizing agricultural production in the upstream region, mitigating the unemployment (social) impacts of land use changes, and providing reliable water supply to the downstream region. The upstream region is divided into subbasins, and a fuzzy-based multiobjective optimization model is used to determine the optimal land uses in each subbasin and water allocation to agricultural lands in the watershed. To illustrate the practical application of the model, a case study at the Aharchay watershed in Iran has been used. Land use planning as an alternative strategy of nonpoint source pollution control is evaluated in this watershed. The study represents a novel and practical mean of integrating water quality and quantity management and land use planning on a watershed scale.