Approccio metodologico per la gestione delle RIS con particolare riferimento alle aree costiere antropizzate. Caso di studio: Piana di Oristano

Water contamination by nitrates from agricultural sources is a major problem in Sardinia (Italy) where Nitrate Vulnerable Zones (NVZs) has been defined in the Arborea reclamation area (W. Sardinia). In this area, intensive agriculture and farming are the mainstays of the local economy. Agricultural practices have seen an increase in the use of animal and chemical fertilizers for enhancing soil productivity. This, accompanied by the intensive use of groundwater resources for irrigation has led to the deterioration of groundwater quality, in areas particularly vulnerable to nitrate contamination. In the test area, the intrinsic nitrate contamination risk from agricultural sources has been evaluated through the combined application of the parametric methods, SINTACS, QI and IPNOA. Risk assessment, using vulnerability and hazard map-ping, is considered a fundamental aspect of sustainable groundwater management. All parameters used in this risk assessment were implemented, classified, weighted and integrated in a GIS environment. The concentration of nitrate pollution in groundwater has been estimated by using numerical methods; the transport numerical model is coupled to a groundwater flow model, obtained using the modular three dimensional finite difference groundwater flow model (MODFLOW), and it is made applying 3-D Multi-Species Transport Model (MT3D). Results show that higher nitrate concentrations are located in those areas where agricultural and livestock farming are concentrated. Therefore, these results could be interesting for future development and long term planning of groundwater protection management. The risk methods adopted has been validated using the measured distribution of nitrates in the groundwater with the different vulnerability classes. Areas where nitrate occurs at concentration higher than 100 mg/l well overlap those areas identified by the model as high risky ones. On the other hand, the areas with nitrate concentration less than 25 mg/l closely match those areas at low and moderate risk. The results obtained with the methods presented in this work may offer a valuable contribution to the existing solutions addressed to nitrate groundwater pollution management. The proposed method to identify action plans aimed at informing and training farmers in much better fertilization management and agricultural practices. In addition, this study provides the political authorities with a planning tool for water resources and soil protection aimed at a sustainable land use and at environmental protection.