A spatial-temporal optimal allocation method of irrigation water resources considering groundwater level

The healthy and sustainable development of irrigation area not only serves as the guarantee of national food production security, but also shoulders the important task of regional ecological security, in which maintaining groundwater level plays an important role. Due to the close relationship between groundwater level and irri-gation recharge groundwater, realizing rational use of water resources under strictly implementing the total limit of water use and holding reasonable groundwater level is of great significance to the healthy development of irrigated areas. Therefore, this study established a spatial-temporal optimal allocation regulation method of irrigation water resources by coupling groundwater numerical technology and the characteristics of hydrological cycle with comprehensively considering the dual constraints between total water consumption and reasonable groundwater depth. Besides, taking Helan County, a typical area of Qingtongxia Irrigation district in Ningxia as an example, a case study on optimal allocation of irrigation water resources was carried out. The results show that compared with the actual current water use situation, the total irrigation water shortage rate of Helan County Irrigation District (HCID) decreases from 21.61% to 21%. Under the combined control of total available water and groundwater depths, it is realized the fairness and balance of water use in different regions and periods by the allocation of water resources in spatial and temporal. Meanwhile, the area located in the reasonable groundwater depth range increased by 1.65% after optimization. Overall, the balanced and optimal allocation method of irrigation water resources with both total water use and groundwater depth control is not only improving the efficient and rational utilization of limited water resources, but also can regulate groundwater depth to guarantee regional ecological health and sustainable development.