A CMIP6-based framework for propagation from meteorological and hydrological droughts to socioeconomic drought

The propagation threshold between different droughts is necessary to investigate the mechanism of drought evolution. At the same time, Dongjiang basin is of great significance in water resource management and regional socioeconomic development, as it is one of the main water sources in South China. However, studies have often been limited to propagation between meteorological and hydrological droughts, while studies on the propagation threshold from meteorological and hydrological droughts to socioeconomic drought have rarely been reported. This study developed a framework for the propagation threshold from meteorological and hydrological droughts to socioeconomic drought. The framework improved the method of pooling and exclusion of droughts and proposed new matching rules for different droughts. Using these rules, meteorological, hydrological, and socioeconomic drought events were consistently matched one by one. From the matched combinations of multitype drought events using copula conditional probabilities, the propagation thresholds from meteorological and hydrological droughts to socioeconomic drought was found. The CMIP6 datasets were applied to build SPI (standardized precipitation index) and SRI (standardized runoff index) for identifying meteorological and hydrological droughts. Socioeconomic droughts based on SWSDI (standardized water supply and demand index) were further evaluated by the SWAT (Soil and Water Assessment Tool) and SD (Supply and Demand) models. Results showed that the integration of the improved pooling and exclusion method and new matching rules would provide accurate and reliable matching among meteorological, hydrological, and socioeconomic drought events in the future. The higher the severity of socioeconomic drought, the larger the propagation threshold of meteorological and hydrological droughts. The threshold for propagation from meteorological to socioeconomic drought was larger than that for propagation from hydrological to socioeconomic drought. In particular, radiation forcing significantly increased the propagation threshold between meteorological or hydrological and socioeconomic droughts. The framework provides a foundation for drought propagation and even socioeconomic drought prediction.