Where drought matters most: A crop calendar-aware index for prioritizing irrigated agricultural drought hotspots in Italy

Drought increasingly threatens irrigated agriculture in Mediterranean regions, where limited water resources, diverse cropping systems, and growing climate variability require tools that can support timely and spatially targeted water management decisions. However, drought assessments based only on climatic anomalies may overlook where water deficits are most relevant for agriculture, since their impacts depend on whether drought occurs during the crop growing season, how much irrigated land is exposed, and the economic importance of the affected crops. This study introduces PRIME (PRiority Index for crop-season drought ManagemEnt), a crop calendar-aware index designed to rank irrigated agricultural areas according to their drought management priority. PRIME combines drought frequency derived from the Standardized Precipitation Evapotranspiration Index (SPEI) computed over local crop-specific growing seasons with irrigated crop distribution and gross production value. The index was applied to 17irrigated crops in Italy over 1951−2022, covering 1.84 million hectares of irrigated farmland. Results identify priority hotspots where recurrent crop season droughts overlap with strategic irrigated production systems, particularly in the Po River Valley and in the irrigated districts of Emilia-Romagna and Veneto. Additional priority areas appear in central Italy and in perennial crop systems of southern regions such as Apulia, Calabria, and Sicily. At the crop level, maize-growing areas most frequently show high management priority, while localized high value systems, including sugar beet, fruit crops, and olives, are often associated with the highest PRIME classes. By translating crop season drought exposure into a priority ranking, PRIME provides an operational and reproducible screening tool to help water authorities, irrigation agencies, and policymakers identify critical areas for drought preparedness, resource allocation, and targeted adaptation in Mediterranean irrigated agriculture.