Evolution of groundwater ecosystem service value in the receiving areas of Beijing-Tianjin-Hebei around the opening of the Middle Route Project of South-to-North Water Diversion

The Middle Route Project of South-to-North Water Diversion (MRP) has effectively increased the amount of available water resources in the receiving areas of the Beijing-Tianjin-Hebei region, curbed the trend of declining groundwater levels, expanded the area of landing funnels, and increased the magnitude of ground subsidence, and enabled the groundwater system to play an important ecosystem service value. This article classified groundwater ecosystem services in the receiving areas of Beijing-Tianjin-Hebei into four categories: provisioning services, regulating services, supporting services and culture services, according to the classification of the Millennium Ecosystem Assessment. We constructed an ecosystem service value assessment index system and a monetized quantitative value assessment model to assess the groundwater ecosystem services value (GESV) around the commissioning of the MRP, and analyzed the contribution of the MRP to the GESV. The results showed that the total annual average of the GESV in the receiving areas of Beijing-Tianjin-Hebei before the water connection was 124.298 billion yuan, and after the water connection was 144.033 billion yuan, of which the value of the regulating and supporting services increased and the value of the supply services decreased. The enhancement of the GESV in the water-receiving areas of Beijing-Tianjin-Hebei by the MRP has increased year by year, and its contribution to the GESV increased from 10.508 billion yuan in 2015 to 49.354 billion yuan in 2019.