Integrating Census Statistics and Gridded Crop-Water Modelling to Assess Irrigation Requirements and Water Withdrawals in Italy

Agriculture is the dominant consumptive water-use sector in many regions and is increasingly exposed to climate variability, rising food demand, and competition for freshwater resources. This study develops a spatially explicit assessment of agricultural irrigation water use in Italy by integrating official agricultural census statistics, gridded irrigation-area data, and crop-specific irrigation-requirement model outputs. ISTAT ۲۰۱۰ agricultural census data were used to characterize irrigated area by crop, irrigation system, and water source at administrative scale, while the Global Map of Irrigation Areas version ۵ (GMIA v۵) provided gridded information on irrigated area and water-source attribution. Crop evapotranspiration and irrigation-requirement data were derived from a gridded daily model based on ERA۵ climate forcing, crop calendars, and soil-water-balance calculations. Spatial preprocessing, reprojection, rasterization, and crop-category harmonization were performed to align all datasets at a common ۰.۰۸۳۳۳۳-degree resolution. The integrated framework was applied nationally and to the Piemonte region as a focused case study, comparing the reference year ۲۰۱۰ with the ۲۰۰۵-۲۰۱۴ mean. Results show that total irrigated area estimated from GMIA and ISTAT is highly consistent at province level, with only ۰.۱۲ percent difference, although larger discrepancies occur for groundwater because the source categories are not directly equivalent. At national scale, aspersion represents the largest irrigated area, whereas Piemonte is dominated by surface sliding and slide infiltration followed by flooding. The estimated irrigation requirements and withdrawals show lower values in ۲۰۱۰ than the ۲۰۰۵-۲۰۱۴ average, with water withdrawals decreasing by about ۱۵.۶ percent in Italy and ۲۳.۷ percent in Piemonte. The findings demonstrate that combining official statistics with gridded crop-water modelling can support evidence-based irrigation planning, spatial prioritization of efficiency improvements, and agricultural water-management policies.

کلیدواژه ها:

Irrigation requirement ، agricultural water use ، ISTAT ، GMIA ، evapotranspiration