Assessing agricultural drought risk and its dynamic evolution characteristics

Assessment of agricultural drought risk is significant for risk division and management. Nevertheless, the drought risk dynamic evolution characteristics have not been revealed. To this end, the agricultural drought conditions are characterized by the standardized precipitation index (SPI), and the time scale of SPI is determined based on agricultural damage data. The joint return periods of various drought severities and durations under different agricultural drought scenarios are calculated by using copula functions. Moreover, drought risk factors (resilience, vulnerability, and exposure) are also used to characterize drought risk. Subsequently, based on the moving window, the joint return period and risk factors in each window are calculated, and agricultural drought dynamics are explored. The Pearl River Basin (PRB) is selected as a case study. Results indicated that: (1) the 4-month most appropriate timescale for the SPI in characterizing agricultural drought based on agricultural damage data in the PRB; (2) risk factors method is more suitable than joint return period in assessing agricultural drought risk; (3) most of the PRB exhibit a significant increasing agricultural drought risk, while the drought risk of the Pearl River Delta has a decreased trend within the past 50 years. Generally, this study show new insights into agricultural drought risk assessment, thus promoting local agricultural drought preparedness and mitigation.