Future Dynamics of Irrigation Water Demand in the Farming Landscape of the Venice Lagoon Watershed under the Pressure of Climate Change

Climate change impacts on the Venice Lagoon Watershed (VLW), an area of 2,038 km2 in the north-eastern part of Italy, are expected to be particularly relevant for agriculture, given that approximately two-thirds of the total area is devoted to field crops, horticulture and market gardens. Farmer's irrigation behaviour plays a crucial role for the sustainability of crop productions and water consumption. In this study, an agent-based model is developed to explore how farmers' decisions affect future water consumption in the VLW. The model is an "agentized version" of a soil water balance model based on the FAO-56 procedure. A climatic projection representing the IPCC A1B scenario is used to produce future daily data about relative humidity, precipitation, temperature and wind speed. In order to inform the farmers about the simulated future weather conditions, two types of meteorological services are made available: (1) a bi-weekly bulletin and (2) the seasonal forecasts. The precision of these services varies according to the selected exogenous information scenario which simulates different conditions, from perfect knowledge to poor forecasts. Using the available forecasts, farming agents take adaptation decisions concerning irrigation and crop management on the basis of their own risk and water saving attitudes. Farmer's attitudes are characterized by fuzzy classification depending on age, relative income and crop profitability. Farming agents' adaptation decisions directly affect the crop and irrigation parameters, which in turn affect future water needs of the area. By incorporating available and future meteorological services, the model allows to investigate farmers' decision making process and the consequent future irrigation water demand for the period 2015 to 2030. This paper describes the conceptual model following the ODD+D protocol. Preliminary results are under analysis.