LAUSR

Abstract Drought loss risk curves can quantitatively assess regional drought and indicate the mechanism of drought hazards. In this study, the drought events were identified using the run theory based on Standard Precipitation Index (SPI) and Composite meteorological drought Index (CI) separately calculated by daily weather data during 1955–2012. The frequency of drought events was calculated by using the Copula function. The yield loss of soybeans under different irrigation levels in dry years was simulated by DSSAT-CROPGRO-soybean model. Finally, the regional drought risk for soybeans in Bengbu city was analyzed by constructing a series of relationship curves among the drought frequency, soybean drought loss, and the irrigation level. The results indicated that (1) both the SPI and CI were applicable to identifying drought events in the selected city, but SPI was more sensitive in identifying short-term drought events, and CI was more reliable in recognizing medium-term drought events. (2) The frequency of drought events during the target crop's growing period and the corresponding yield loss rate satisfied the semi-logarithmic function, and the average values of their determinant coefficients were 0.68 and 0.74 based on SPI and CI, respectively. (3) Irrigation could significantly reduce soybean yield loss in non-extreme drought events. Therefore, drought loss risk curves can reflect regional drought risk more quantitatively and facilitate the assessment and management of regional drought risk.