Mapping Irrigation Priority Areas and Hot Spots in Northeast Italy: A Simplified Framework for Water Authorities

Productive agricultural areas of Italy’s northeast are under ever-increasing strain from extreme events, such as drought. Largely irrigated agriculture, the northeast is a producer of key staple crops like corn and wheat that underpin food security both locally and globally. Irrigation water management in the area typically falls under the control of regional water authorities (Consorzi di Bonifica). Staff within water authorities include both farmers and technical experts; thus, knowledge of water management may vary. Regional drought risk and the limits of technical capacity among water authority employees highlight the need for a framework to bridge gaps in technical knowledge. Identification of priority areas and hot spots during the key irrigation months, May to September, is critical to sustaining agricultural production and improving resilience to extremes such as drought. A threshold-based framework using standard drought-related variables, Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), and Surface Soil Moisture (SSM) from largely code-free sources at a 1 km spatial resolution and at a monthly timestep can help to identify regional priority areas and persistence-based hot spots. When comparing monthly priority from May to September across three distinct rainfall years, a wet (2019), normal (2020) and dry year (2022), results showed greater variability across months in 2019 and 2020, regardless of one year being wetter than the other. In the dry year, there was a notable increase in priority areas moving into the middle summer months, with a peak in July of the highest priority level. Results align with existing 2022 drought research, which shows that extremes were highest in the middle summer months. Persistence-based hot spots indicated that, for each month across the three years of interest, higher-priority hot spots were more prevalent in June and July, with the highest-priority hot spots primarily located in the central and eastern parts of the study area, respectively. Past drought events, such as the extreme event in 2022, have led to water shortages and water-use restrictions. The increasing frequency of such events may require decision-makers within water authorities to prioritize irrigation water use in the face of shortages or restrictions, and a reproducible framework can aid in such decision-making.