Integrated modelling for agricultural policies and water resources planning coordination

• An economic model, a hydrological model and an optimisation tool are integrated.
• The simulation system aims at supporting water resources planning at the basin scale.
• In particular, effects of Common Agricultural Policy on water demand can be explored.
• The simulation system is applied to a real world basin and the results are discussed.

Pressures due to agricultural activities play a major role in the status of water resources systems. The evaluation of the effects of agricultural policies is therefore a key problem in water resource planning and management. The work presented in this paper is an attempt to include the predictable effects of the Common Agricultural Policy (CAP) of the European Union (EU) in the process of water resources planning at the basin scale prescribed by the EU Water Framework Directive (WFD). The approach is based on the combined use of three models: (i) an economic model used to predict the likely land use scenarios at the basin scale following CAP reform; (ii) a spatially distributed hydrological model for the assessment of the related irrigation water requirements; and (iii) a decision model supporting stakeholders and decision makers in the process of water resources planning. The paper presents an application to a pilot study area in Northern Italy. The results highlight how the CAP may produce an adjustment in the agricultural sector, with a shift towards more extensive land use and to a greater diversification of production. The predicted changes in land use type and distribution are shown to have significant influence on water requirements, with a generalised decrease of their amount, which may exceed 10% in some areas. In turn, the decrease of irrigation demand can be exploited to achieve a higher degree of satisfaction of other water users in the basin and can improve the attainment of the WFD objectives.