Water yield service flow assessment under future SSP-RCP scenarios in the Yellow River Basin: Coupled effect of climate and land use change

As extreme climate events and human activities increase in frequency, the unreasonable use of water resources and imbalance in supply–demand pose a serious threat to human society. The concept of water yield service flow (WYSF) introduces a new perspective into the research on water supply and demand (WSD) coupling mechanism and water resources management. However, most of the studies on WSD only consider limited factors in their simulation and neglect the supply–demand coupling mechanism, leaving the research from the standpoint of WYSF at a stage that awaits further exploration. This study constructed a coupled analysis framework to examine the impact of Climate and Land Use Change (CLUC) on WSD, aiming to reveal the flow pathways of water under the context of environmental changes in the Yellow River Basin (YRB). On the basis of the supply–demand coupling mechanism, the spatial pathways of WYSF were finally mapped. The results indicated that: (a) The magnitude of climate change is the greatest under the SSP585 scenario, whereas it is more moderate under the SSP126 scenario. (b) Three scenarios exhibit an identical spatial pattern of land use change, which is primarily characterized by the expansion of impervious surface on cultivated land and the encroachment of forest and grassland into water. However, the extent of expansion and reduction varies, with the SSP585 scenario showing the most dramatic change, followed by the SSP126 and SSP245 scenarios. (c) Generally, under the three scenarios, sub-basins with greater supply are located in the upper and lower reaches, whereas areas with greater demand tend to cluster in the northwest and middle and lower reaches. This showed that there is an obvious mismatch in WSD. (d) The analysis of the WYSF networks showed that the introduction of WYSF concept for research can more accurately reflect the spatial match of WSD.