Deficit irrigation strategy impacts on economic, social, and environmental indicators: evidence from the lands covered by Qare-soo watershed in Iran

Uncontrolled extraction of surface and groundwater for agricultural production in the Qare-soo watershed of Golestan province has exceeded its potential and has seriously endangered this vital resource. Therefore, there is a gap of 50 million cubic meters between the current and potential water extraction in this watershed. The agricultural sector is the largest water consumer in the country, so providing comprehensive water resource management practices and developing the right policies in this sector seems necessary. In this study, using the Positive Mathematical Programming method (PMP) with Maximum Entropy (ME) approach, the deficit irrigation (DI) strategy impacts on economic, social and environmental indicators in the lands covered by the Qare-soo watershed has been investigated. The required data were obtained using the two-stage cluster sampling method by completing 163 questionnaires by the farmers of the watershed in 2017–2018. Four scenarios, i.e., full irrigation, 5%, 10%, and 15% DI were conducted. The results showed that by the implementation of the DI, the cropping pattern has been severely affected and has shifted to higher economical crops, and also the simulation results of the PMP model showed that the cultivation area reduced by 7.1%, 14.4%, and 19.8%, respectively. As the results showed, the intrinsic value of water in the watershed is much higher than the amount paid by farmers. Moreover, the effects of DI on economic, environmental and social indicators in the watershed were examined. Therefore, the application of DI policy along with changing the cropping pattern can effectively reduce excessive water consumption and help to preserve and sustainability of water resources in the Qare-soo watershed.