Spatiotemporal dynamics of blue and green water resources in a mountainous watershed: A case study of the Wujiang River Basin, China

Abstract

Study regionWujiang River Basin, China. Study focusBlue and green water play key roles in water management and sustainable development in the Wujiang River Basin. It is essential to conduct a comprehensive study on the availability of blue and green water resources due to the uneven distribution of water resources in the basin. In this study, the monthly, seasonal, and interannual variations in blue and green water resources were analyzed during 1985–2014, and the changes in blue and green water resources were predicted for the period 2015–2100 based on the 5 Coupled Model Intercomparison Project Phase 6 (CMIP6). New hydrological insights for the regionFrom 1985–2014, blue water resources were dominant in the Wujiang River basin, accounting for 53.6% of the total water resources. Blue water resources exhibited an increasing trend, while green water resources exhibited a decreasing trend. Precipitation exhibited a much more significant impact on blue water resources than on green water resources. The spatial distribution of blue and green water resources in the basin is uneven, where the blue water resource with an annual average of 629.5 mm, indicating an increase followed by a decreasing trend from upstream to downstream. The green water resources had an annual average of 544.7 mm, with a decrease followed by an increasing trend from upstream to downstream. Delta and multi-model ensemble (MME) can effectively reduce the uncertainties associated with CMIP6 model output. Annual precipitation and mean annual temperature increase from 2015 to 2100 in SSP1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5. Compared to the baseline period, blue water resources show the highest growth in the recent (2015–2040) and intermediate (2041–2070) periods in SSP1–2.6, i.e., by 4.9% and 13.7%, respectively. In the final period (2071–2100), blue water resources exhibit the highest growth in SSP5–8.5, i.e., by 21.5%. The future projections indicated that the uneven spatial distribution of blue water resources in the basin will persist. This study improves our understanding of the blue and green water resources in the Wujiang River Basin under climate change scenarios and can provide valuable insights for integrated water resources management in the Wujiang River Basin.