Optimizing groundwater recharge plan in North China Plain to repair shallow groundwater depression zone, China

The North China Plain is one of the main grain producing areas in China. However, over -exploitation has long been unsustainable since the water supply is mainly from groundwater. Since 2014, the South-to-North Water Diversion Project's central route has been charted to the integrated management of water supply and over-exploitation, which has alleviated the problem to a certain extent. Although the Ministry of Water Resources has made many efforts on groundwater recharge since 2018 most of which have been successful, the recharge has not yet been sufficiently focused on the repair of shallow groundwater depression zones. It still needs further optimization. This paper discusses this particular issue, proposes optimized recharge plan and provides the following recommendations: (1) Seven priority target areas are selected for groundwater recharge in alluvial and proluvial fans in the piedmont plain, and the storage capacity is estimated to be 181.00x108 m3; (2) A recharge of 31.18x108 m3/a is required by 2035 to achieve the repair target; (3) It is proposed to increase the recharge of Hutuo River, Dasha River and Tanghe River to 19.00x108 m3/a and to rehabilitate Gaoliqing-Ningbailong Depression Zone; increase the recharge of Fuyang River, Zhanghe River and Anyang River to 7.05x108 m3/a and rehabilitate Handan Feixiang-Guangping Depression Zone; increase the recharge of Luanhe River by 0.56x108 m3/a and restore Tanghai Depression Zone and Luanan-Leting Depression Zone; moderately reduce the amount of water recharged to North Canal and Yongding River to prevent excessive rebound of groundwater; (4) Rech-arge through well is implemented on a pilot basis in areas of severe urban ground subsidence and coastal saltwater intrusion; (5) An early warning mechanism for groundwater quality risks in recharge areas is estab-lished to ensure the safety. The numerical groundwater flow model also proves reasonable groundwater level restoration in the depression zones by 2035.