Analyses of spatial and temporal characteristics of water conservation function in Qaidam Basin

Water conservation is the dominant function of ecological system services in the Qaidam Basin, and it plays an important role in protecting the ecological security of the Tibetan Plateau. Based on a comprehensive analysis of land use, climate, soil, and terrain data in the Qaidam Basin, the spatial and temporal characteristics of water conservation function of different ecosystems in the basin were analyzed using the InVEST model, and the cold and hot spot distribution patterns were calculated. The results showed that: 1) Grassland was the main vegetation type in the Qaidam Basin (occupying 30.00% of the total Qaidam Basin area) and was mainly distributed in mountainous areas, with its area increasing from 1980 to 2018. 2) The average annual amount of water yield and total water conservation in the Qaidam Basin was 32.17 × 10⁸ and 12.17 × 10⁸ m³, respectively. The temporal and spatial variations of water conservation function varied significantly from 1980 to 2018. The spatial distribution of water conservation was consistent with that of precipitation. The water conservation of mountainous areas above 3500 m accounted for 91.39% of the total water conservation in the Qaidam Basin. Grassland was the main water conservation vegetation, and its water conservation value accounted for 95% of the total water conservation in the basin. The water conservation amount increased from 1980 to 2018, and the increase in high and medium coverage grassland areas was the major factor that improved water conservation. 3) The hot spot region of the long-time average annual value of water conservation was mainly distributed in the east, southeast, and south mountain areas, and accounted for 10.93% of the total basin area. This region has abundant precipitation and is mainly distributed with medium and high coverage grasslands. This region has a strong water holding capacity and water conservation function owing to the high coverage of vegetation. The cold spot region of the water conservation function was mainly distributed in the northern, central, and northwestern regions of the basin. Owing to sparse vegetation, low precipitation, and high evapotranspiration, this region has a low water conservation function. This study identified the key areas for water conservation in the Qaidam Basin and the importance of grassland water conservation, which can be used as a reference for formulating grassland ecological protection policies in the basin.