Groundwater imbalance and its mutual feedback relationship with land use in West Liaohe Plain

The West Liaohe Plain (WLP) is an important ecological barrier in northern China. Due to the increase in irrigation water since 2004, the groundwater level has continued to decline in the WLP. To investigate the regional groundwater imbalance, ecological effects, and their influence factors, the regional groundwater balance and its mutual feedback relationship with land use in the WLP were analyzed by using the methods of groundwater level measurement and long-term monitoring, the spatial correlation analysis, water balance analysis, land use transfer matrix, and contribution to groundwater level change. The results show that the groundwater level in the WLP in 2020 decreased by an average of 2.23 m compared with that in 2004, with a groundwater storage decrease rate of 10.90×10⁸ m³ per year (average value). The large decline of groundwater level occurs in the centralized irrigated area in the central part, in particular in the Keerqin District, Tongliao City. The contribution of groundwater extraction to the groundwater level decrease is 33% in the WLP and more than 50% in the Keerqin district. In the area with a groundwater level decrease, the groundwater level depth increases from 4.71 m to 8.34 m, resulting in grassland degradation and coverage reduction. The sustainable extraction of groundwater in WLP is 24.28×10⁸ m³/a. Increased groundwater extraction for agricultural irrigation is the main reason for the groundwater level decrease. To prevent the continuous groundwater level decline, comprehensive management methods, such as improving the capacity of water-saving irrigation, adjusting the planting structure, introducing water from the outer watershed, and reducing the amount of groundwater extraction are suggested. This study can provide technical support for regional agricultural cultivation planning and groundwater management and protection.