Abstract:

[Objective] This study aims to conduct a comprehensive evaluation of the ecological benefits of the South-to-North Water Diversion Project (SNWDP) by systematically quantifying the ecological benefits in the water-receiving areas during the first phase of the Middle Route Project. [Methods] The water receiving area was divided according to administrative units and assessed using statistical and remote sensing data. Taking 2014 as the base year and 2018, 2020, and 2023 as evaluation years, we evaluated the ecological benefits brought by project-supplied water in Beijing, Tianjin, 11 counties (or cities) of Henan, and 6 counties (or cities) of Hebei. Ecological benefit index systems were established for forest land, urban green space, wetlands, water bodies, and groundwater ecosystems by integrating the function value method and the equivalent factor method. For forest land, urban green space, and groundwater ecosystems, multiple ecosystem service functions were quantitatively analyzed. The market value method, replacement cost method, and other valuation methods were used to estimate the unit prices of each function and calculate their total service value. For wetlands and water body ecosystems, ecological benefits were calculated using the equivalent factor method based on regional characteristics. A spatiotemporal precipitation adjustment factor was introduced to dynamically adjust the factor values in the basic equivalent factor table, thereby determining the value of one standard unit of ecosystem service equivalent factor. [Results] Cumulative ecological benefits generated by the water supply from the first phase of the Middle Route Project amounted to 44.859, 18.328, and 37.102 billion yuan in each evaluation period, respectively. Wetlands and water bodies accounted for the largest proportions, at 64.90%, 58.98%, and 46.98%, respectively. From 2015 to 2018, new ecological benefits from water bodies and wetlands reached 24.724 and 4.391 billion yuan, respectively; for 2019-2020, they were 9.100 and 1.709 billion yuan; and from 2021 to 2023, new ecological benefits from wetlands and water bodies were 11.079 and 6.352 billion yuan, respectively. The annual average new ecological benefits for each period were 11.215, 9.164, and 12.367 billion yuan, indicating that the project’s water supply generated approximately 10 billion yuan of ecological benefits per year in the water receiving areas. In addition, the ecological benefit value per cubic meter of water varied across provinces and cities. In Beijing, the values were 1.64, 1.38, and 3.01 yuan; in Tianjin, 3.34, 2.19, and 0.52 yuan; in Henan’s 11 counties, 8.16, 5.06, and 3.79 yuan; and in Hebei’s 6 counties, 6.12, 2.69, and 4.07 yuan, respectively. The benefit value ratios for Beijing∶Tianjin∶Henan∶Hebei in each evaluation period were 1∶2.10∶4.99∶3.74, 1∶1.59∶3.66∶1.95, and 1∶0.17∶1.26∶1.35, respectively. [Conclusion] This study provides a case reference for ecological benefit evaluation the follow-up projects of the SNWDP and other inter-basin water diversion projects. It provides technical support for the scheduling and utilization of ecological benefits of the Middle Route Project, and further provides a calculation basis for promoting the establishment of horizontal ecological compensation standards between the water receiving and source areas.

Key words: Middle Route Project of South-to-North Water Diversion, ecological benefit evaluation, indicator system, function value method, equivalent factor method, horizontal ecological compensation standards