Simulation supported scenario analysis for water resources planning: a case study in Northern Italy

The work presents the results of a comprehensive modelling study of surface and groundwater resources in the Muzza-Bassa Lodigiana irrigation district, in the Southern part of the densely-settled Lombardia Plain (Northern Italy). The activity focused on the assessment of the impact of changes in land use and irrigation water availability on the distribution of crop water consumption in space and time, as well as on the groundwater resources in the area. In order to carry out the research, a distributed, integrated surface water-groundwater simulation system was implemented and applied to the study area. The system is based on the coupling of a conceptual vadose zone model with the groundwater model MODFLOW. In order to assess the impact of land use and irrigation water availability on water deficit for crops as well as on groundwater system in the area, a number of management scenarios were identified and compared with a base scenario, reflecting the present conditions. Results show that changes in land use may alter significantly both total crop water requirement and aquifer recharge. Water supply is sufficient to meet demand under present conditions and, from the crop water use viewpoint, a reduction of water availabity has a positive effect on the overall irrigation system efficiency; however, evapotranspiration deficit increases and is concentrated in July and August, when it may be critical for maize crops