Prediction and evaluation of groundwater level changes in an over-exploited area of the Baiyangdian Lake Basin, China under the combined influence of climate change and ecological water recharge.

Groundwater (GW) and surface water (SW) are important components of water resources and play key roles in social and economic development and regional ecological security. There are currently several stresses placing immense pressure on the GW resources of the Baiyangdian Lake Basin (BLB) in China, including climate change. A series of ecological and environmental challenges have manifested in the plain area of the BLB due to long-term over-exploitation of GW, including regional declines in GW level, aquifer drainage, land subsidence, and soil secondary salinization. Climate change may aggravate environmental challenges by altering GW recharge rates and availability of GW. This study applied the fully processed and physically-based numerical models, MODFLOW and the Soil & Water Assessment Tool (SWAT) in a semi-coupled modeling framework. The aim of the study was to quantitatively analyze changes to shallow GW levels and reserves in the plain area of BLB over the next 15 years (2021-2035) under climate change and different artificial recharge schemes. The results indicated that GW storage and levels are rising under the different GW recharge schemes. The maximum variation in the GW level was 20-30 m under a rainfall assurance rate of 50% and water level in the depression cone increased 14.20-14.98 m. This study can act as a theoretical basis for the development of a more sustainable GW management scheme in the plain area of the BLB and for the management and protection of aquifers in other areas with serious GW overdraft.