The Effectiveness of the South‐to‐North Water Diversion Middle Route Project on Water Delivery and Groundwater Recovery in North China Plain

Abstract

AbstractThe South‐to‐North Water Diversion Middle Route Project (MRP), which started its operation in December 2014, was designed to transfer water from Danjiangkou Reservoir (DR) in Hanjiang River Basin to North China Plain (NCP) to alleviate water shortage and long‐term groundwater depletion in the water‐receiving region. This study investigates the effectiveness of actual MRP operation during 2015–2018 using the observed water budget data collected from DR and the groundwater level data from 559 monitoring wells. Assuming that MRP was in operation during 2005–2014, ensemble water diversion simulations were performed to study the sensitivity of MRP effectiveness to two important factors: the downstream water demand of DR (Dwd) and the ratio (Ir) of water diversion volume (Qd) replacing groundwater pumping in NCP. Even though the observed and simulated mean annual Qd during 2015–2018 (i.e., 4.3 and 7.0 km3/year, respectively) failed to meet the original water delivery target of 9.5 km3/year due to its short operation and the coincidence with a dry cycle, MRP is effective in groundwater recovery as an increasing trend (+0.3 km3/year) in groundwater storage (GWS) was observed in NCP during 2015–2018. MRP's effectiveness is sensitive to Dwd and Ir. Dwd should not exceed 23.0 km3/year to guarantee Qd reaching the original target, and Ir should not be less than 33% to guarantee GWS recovery. Those findings suggest that a reasonable decrease of Dwd and an increase of Ir are the recommended pathway to ensure the effectiveness of MRP in meeting both water delivery and groundwater recovery targets.