The effect of increasing water use efficiency on improving the status of groundwater resources using WEAP model in Qazvin Plain

Introduction
Water supply and proper management of water resources is one of the serious challenges of water managers and researchers. The optimal management and finding suitable solutions in arid and water scarce areas to satisfy the human needs requires a careful attention to the optimal allocation and prioritization of water consumption among different sectors. Competition over water consumption in different sectors is one of the main causes of conflict and ultimately more exploitation of water resources and the resulting problems. Many regions of the world face significant challenges in freshwater management. Limited water resources allocation, environmental quality, and sustainable water use policies are growing concerns. A comprehensive water resources management approach is essential in different climatic and socio-economic conditions.
Materials and Methods
In this study, the availability and uses of water resources in Qazvin plain were evaluated using WEAP simulation model platform. The components of the hydrological cycle and rainfall-runoff process have been simulated using WEAP model at the watershed scale. Toward this attempt, different management scenarios regarding the reduction in the amount of demand for agricultural, drinking and industrial water have been developed. Also, increasing the water use efficiency and reduction in water losses were proposed. Finally, the effects of management scenarios on water resources were compared over the study area. Also, the results of proposed scenarios have compared with the continuing the current condition as a base case scenario
Results and Discussion
The results of the reference scenario showed that groundwater storage has a declining trend and the largest decrease has been occurred during 2017 and 2018 years. The amount of decreasing water resources was approximately 400 million cubic meters. While, according to the increasing groundwater storage and efficiency improvement scenario, the increase in the amount of available water will be equal to 1500 Million cubic meters increases. Comparing the amount of unmet demand between the two scenarios showed that in the scenario of increasing irrigation efficiency, the amount of water demand in the study area will decrease by about 40 million cubic meters.
Conclusion
The present study showed that through applying appropriate management measures in the region, it will be possible to rehabilitate groundwater resources and the current situation of the water crisis will improve. Otherwise, valuable groundwater resources in the study area will be seriously threatened and irreparable consequences such as degraded groundwater quality, land subsidence, drying or reduced well discharge will occur. Therefore, a balance between exploitation and available water resources in the study area is essential. According to the results, the replacement of modern irrigation systems with traditional irrigation methods in the Qazvin plain will reduce the loss of water resources. In addition, solutions such as artificial aquifer recharge can be considered in the restoration of water resources. Accordingly, conservation of water resources is necessary by implementing practical solutions due to the drought and water shortages in the region. the study of hydrological effects of water resources development plans using modeling approaches should be considered.