Assessing groundwater use in irrigation districts with multiple resources (MIGRAD)

A water allocation model at farm-scale was developed to interpret water allocation patterns in an intensive agricultural district of Southern Italy, supplied by groundwater and surface waters (from reservoir) with variable costs and distinct management regimes. The model aims at evaluating the impact of farm-scale water costs on water resources management and groundwater conservation at district scale. Semi-structured interviews were carried out involving local stakeholders to define (i) the relationship between irrigation source selection and water tariff applied by the irrigation district, and (ii) the conjunctive use of groundwater based on water cost convenience. It was demonstrated that farmers' choice depends on the ratio between volumetric water tariff and the groundwater pumping cost at farmscale. The results also demonstrated that a restrictive water tariff policy applied during drought periods produced an increase in the groundwater use instead of reducing the water consumption. The model allowed to analyze the drivers influencing farmers' behaviour, thus assessing the effectiveness of water protection policies, specifically those related to water tariff.