Research on the Ecosystem Service Value of the Xiaolangdi Reservoir Area Using the Value Equivalence Method

Land-use transformation driven by large-scale water conservancy projects profoundly reshapes regional ecosystem structures and the supply capacity of ecosystem services, yet targeted quantitative assessments linking land-use evolution to ecosystem service values (ESV) in the Xiaolangdi Reservoir resettlement zone remain insufficient, restricting scientific ecological management and territorial spatial governance for reservoir-affected counties and districts. This study draws on the latest ecosystem service valuation theories proposed by domestic and international scholars and applies the value equivalence method to quantify variations in land-use pattern changes and ESV across nine resettlement counties and districts (including the Sanmenxia urban area) affected by the Xiaolangdi Reservoir relocation project. Data collected included historical records (1995–2020), digital elevation models (DEM, 30 m resolution), and land-use information. By applying value equivalence theory and analyzing land-use change impacts, the study calculated changes in ESV and conducted sensitivity analyses across different land types. The findings reveal significant impacts on surrounding counties following the reservoir’s completion. Data indicate that the expansion of water areas drove the total ESV to rise from US$3.3261 billion in 1995 to a peak of US$3.6557 billion in 2010, followed by a decline to US$3.6128 billion in 2020. The most pronounced changes occurred during the first five years post-reservoir filling (2000–2005), marked by elevated water sensitivity indices. This research clarifies the differentiated responses of ecosystem service functions to land-use changes across reservoir-affected counties, provides quantitative decision-making support for coordinated ecological restoration, cultivated land protection, and sustainable land management in the resettlement area of the Xiaolangdi Reservoir, and offers a replicable technical framework for ecosystem service valuation of large sediment-laden river reservoir regions worldwide.