Future river basin health assessment through reliability-resilience-vulnerability: Thresholds of multiple dryness conditions

Increasing dryness conditions under global warming are posing severe threats to water resources management in China. Projecting river basin responses to dryness conditions is beneficial to effectively managing water resources. However, existing studies have seldom considered the impact of multiple dryness conditions on future river basin health under global warming. Therefore, we combine the 3- and 12-month standard precipitation evapotranspiration index (SPEI) and reliability-resilience-vulnerability framework (RRV) to map future river basin health based on the responses of basins across China to different dryness conditions from 2021 to 2050. The calculation is based on downscaled outputs of 10 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for three future emission scenarios (i.e., RCP2.6, RCP4.5 and RCP8.5). The results show that water deficits are projected to occur in most areas of China and significantly increase in the basins located in the northern part of China in the next 30 years due to global warming effects. The conditions in parts of the basins located in the northern part of China (especially in the Northwest River basins and Yellow River basin) are projected to be unhealthy and deteriorate significantly in the future, while the basins located in the southern part of China are projected to be moderate. The health status is anticipated to be worse under the RCP8.5 scenario than the RCP2.6 and RCP4.5 scenarios. Integrated results from the three thresholds indicated that normal dryness is applicable to most areas of northeastern, northern and southern China, while abnormal dryness is applicable to the remaining areas. Our findings could help reduce the impact of future dryness conditions on water resources and provide insights into risk planning and management for river basins in China under global warming.