Optimal Water Allocation in Zarrineh River Basin: PSO-WEAP Model

A simulation-optimization framework is presented for allocating releases from Bukan Dam, the largest infrastructure in Urmia Lake Basin, to downstream uses in Zarrineh river basin in Iran. The framework links the water evaluation and planning system (WEAP) simulation module and particle swarm optimization (PSO) algorithm. WEAP by itself optimizes spatial water allocations to demand nodes in a single time period terminal subject to known demand priorities and supply preferences. However, PSO linked to WEAP determines optimal reservoir releases and downstream water allocations over a multi-period planning horizon. The PSO objective function is minimizing the sum of squared water shortages over the planning horizon considering the end-of-year reservoir storage conditions. Results of the model application in year 2012-2013 reveal different demands are met satisfactorily, whereas historical operations have led to shortages in meeting Lake Urmia's environmental water requirement.