Assessment of Water Yield and Water Purification Services in the Arid Zone of Northwest China: The Case of the Ebinur Lake Basin

Assessing how land-use changes will affect water-producing ecosystem services is particularly important for water resource management and ecosystem conservation. In this study, the InVEST model and geographical detector were used to assess the water ecosystem service functions of the Ebinur Lake Basin and analyze their relationship with land-use changes. The results show that in the past 25 years, the water yield of the study area showed a trend of a strong yield at first and then a weaker one; there was a relatively large water yield in the west and southeast regions of the basin. The order of water yield for different land-use types is as follows: forest land > grassland > water area > unused land > crop land > construction land. After 2010, the output load of nitrogen and phosphorus increased; thus, the water purification ability weakened. The main land-use types in areas that demonstrate a large change rate in water purification capacity in the basin are cultivated land and construction land. Changes in the two water ecosystem services were associated with land-use changes. Geodetector analysis results further validated this conclusion. This study proposes a viable, replicable framework for land-use decisions in ecologically fragile watersheds. This study not only helps to gain insight into urban growth patterns in the study area but also helps to inform different land-use stakeholders.