Contrasting Effects Of Climate And Lulc Change On Blue Water Resources At Varying Temporal And Spatial Scales

Blue water (BW) resources are of vital importance for human beings and ecosystem health. Disentangling the contributions of varying climate and land use/land cover (LULC) changes on BW changes is thus crucial and urgent for intelligent water governance. To this end, this study takes the Yellow River Basin (YRB) as a case study of the region that has been undergoing serious water deficit issues, and quantifies the climate and LULC change impacts on BW (water yield and deep aquifer recharge) at varying spatial scales for two periods: 1980-2000 and 2000-2015. Four major results were obtained. First, climate and LULC changes resulted in opposite impacts on BW in the two periods. In 1980-2000, BW driven by climate and LULC changes was decreased, but increased in 2000-2015. Second, climate and LULC change contributions to BW changes were largely scale-dependent. For the whole YRB, the contribution of climate change to BW change were >92% in both periods. For most sub-basins, LULC change, however, played a major role in controlling BW changes, which were either positive or negative, yielding a minor contribution of LULC change to BW for the whole basin. Third, urbanization was important in controlling BW changes. Urbanization-driven LULC change contributed to >80% of BW changes in urban areas. In comparison, climate change contributed to >55% of the BW changes in vegetated areas (cropland, forest, and grassland). Fourth, the dominant land use types for BW changes altered for the past decades. Compared with the impact in the first period, the grassland contribution to BW changes decreased more than 30%, but the forest and urban land contributions both increased over 10% in the second period. Our study provides deep insights regarding climate and LULC change impacts on BW in the YRB, and has immediate implications for land use conversion planning.(c) 2021 Elsevier B.V. All rights reserved.