Agricultural drought hazard assessment from the perspective of the impact of continuous drought on actual crop transpiration

Drought hazard assessment is essential for drought risk reduction, and transpiration sensitively reflects crop responses to continuous drought. The DSSAT-CERES-Maize was calibrated by adjusting genetic parameters and validated using four-season experiment data of summer maize. The daily potential and actual transpiration were simulated to construct a crop transpiration drought index (CTDI), which is defined as the relative deviation of actual transpiration from potential transpiration. The CTDI was compared with commonly used indices, validated against drought records, and subsequently applied to identify the spatiotemporal evolution of maize drought hazard and drought-prone zones and periods across six cities in the Huaibei Plain from the 1960s to the 2010s. Temporally, drought hazard at the seedling and milking stages decreased significantly, particularly in the central and southern regions. Spatially, Fuyang, Huainan, and Bengbu exhibited the highest hazard during the maize growing season. Suzhou experienced consistently low hazard, whereas Huaibei showed substantial variability. The central region was characterized by high drought intensity and prolonged drought duration, while drought severity in the south declined over time. These findings indicate that the CTDI provides a sensitive and accurate method for assessing agricultural drought hazard. Drought risk reduction strategies should prioritize the maize milking stage in Fuyang, Huainan, and Bengbu.