Water Balance Based Sustainability Analysis of Supply and Demand, Towards Developing a Hybrid Index (Case Study: Aharchay Watershed)

Planning of water systems in order to be ready for future development conditions needs further studies on the estimation sustainable levels of demands. In this study a threefold approach is taken for estimating sustainability level of supply and demand in Ahachay Watershed in northwestern part of Iran as a case study. In the first method, the internal flows and the origins and final uses of the total resources for each subsystem are estimated and sustainability use index is calculated by physical input output table. In the second method a simulation model is utilized to estimate reliability, resiliency, vulnerability, and maximum deficit for a watershed to determine a sustainability index. In the third method, for evaluating the movement toward sustainability, an index is developed. This index includes indicators which are the difference between supply and demand, percentage of the satisfied demand, productivity of water resources, and an indicator for evaluating the reduction of aquifer storage. Finally these methods are compared and a hybrid index combining the indices is developed. This hybrid index can be used for evaluating the planning scenarios and for maintaining and improving the sustainable state of supply/demand for the region. Keywords: