Copulas-based bivariate socioeconomic drought dynamic risk assessment in a changing environment

As the only unnatural phenomenon among the four drought types, socioeconomic drought exerts direct negative impacts on socioeconomic system. Socioeconomic drought is closely related to regional sustainable development, which however is received the least attention. Therefore, this study aims to construct a practical framework to fully assess socioeconomic drought dynamic risk. Based on an improved Multivariate Standardized Reliability and Resilience Index (IMSRRI) and copulas function, the joint return periods of different grades drought were calculated to assess the drought risk from a macro perspective, while three drought risk indicators (resilience, vulnerability, and exposure) were adopted for drought risk assessment from a micro perspective. In addition, a 30-year sliding window was applied on the IMSRRI series to explore the dynamic drought risk in a changing environment. Furthermore, the linkages between drought risk indicators and teleconnection factors (Arctic Oscillation (AO), El Nino Southern Oscillation (ENSO), and Pacific Decadal Oscillation (PDO)) were explored. The upper Yellow River Basin (UYRB) was selected as a case study, and the study period is from 1959 to 2010. Results indicate that: (1) the 'boolean AND' joint return periods of the moderate, severe and extreme drought in the UYRB were 5.03, 11.7, and 40.78 years, respectively, and the resilience, vulnerability and exposure values of socioeconomic drought were 0.11, 14.38, and 0.37, respectively; (2) the year of 1995 was the turning point of socioeconomic drought risk (before 1995, socio-economic drought risk was decreasing, after 1995, socioeconomic drought risk was increasing), which corresponds well to that of the IMSRRI series; and (3) socioeconomic drought risk is significantly associated with teleconnection factors, with the descending correlation order of PDO > ENSO > AO. This study sheds new insights into socioeconomic drought dynamic risk assessment in a changing environment.