Abstract

To reach social and economic sustainability in arid and semi-arid areas under water scarce situations, it is important to promote efficient use of water through improved management of water resources. This paper develops a nonlinear discrete-time dynamic model to describe the operation of a single-purpose reservoir during the irrigation season. The model hybridizes the dynamics associated with the water released from a reservoir to the actual water used by crops at farm level. The impact on crop yield because of water deficit and the effect of soil moisture dynamics on crop water requirements are considered by an integrated soil water balance model. As the developed model is a nonlinear one, it is solved using a new global optimization algorithm, namely particle swarm optimization (PSO). The model provides an irrigation time interval in each growth stage and determines the optimal distribution of area, the water to each crop and the total farm income. The model’s applicability is illustrated through a case study of Mirzakhanlu Reservoir system in Northwestern Iran. Also, the consideration of economic benefits in the objective function and its effect on the water allocation decisions for crops are studied. Thus, the output from the model contains initial storages, releases, overflows and evaporation losses for each 10-day period on the reservoir side; and allocation of water, actual evapotranspiration and initial soil moisture for each crop for each 10-day period on the field side, therefore facilitating decision making for optimal utilization of the available water resources