Soil degradation has both indirect and direct effects on the quality of surface and ground waters. In this sense, agriculture is one of the key activities causing water quality degradation in many parts of Mediterranean systems. In the European Union, the purpose of the Water Framework Directive (European Commission, 2000) is to establish a framework for the protection of inland surface, transitional, coastal and ground waters too. A major source of surface and ground water pollution is the diffuse contamination caused by nitrates in agricultural lands. This specific water protection was regulated by the Nitrates Directive (ND, 1991/676/EC), which in Spain was developed by a Royal Decree (261/1996/BOE), and in Andalusia region by a Decree (36/2008/BOJA) for the designation of water quality vulnerability zones (22 zones) and an Order of the Regional Government of Andalusia (18.11.2008/BOJA) to establish the action programs (1 unique program) to be implemented by farmers. However, the Nitrates Directive considers that different action programs may be established for different vulnerable zones or parts of those areas. Also, these action programs must take into account scientific and technical information that are available on each particular soil and climatic conditions, such as rainfall erosivity, length of the growing season, slope, soil infiltration and soil denitrification capacity. Within this context, the agro-ecological decision support system MicroLEIS DSS (technology developed by CSIC-IRNAS and transferred to Evenor-Tech, www.evenor-tech.com) is considered a very appropriate tool to include the soil and climatic attributes for a better identification of vulnerable zones and formulation of action programs. In this paper, the MicroLEIS DSS modelling infrastructure to predict soil erosion and contamination risks (ImpelERO and Pantanal models, basically) is discussed, as a scientific approach to identify detailed vulnerable areas, and formulate site-specific management plans for sustainable water use and protection in Andalusia region. The high variability of the results from this agro-ecological land evaluation research in Water Quality Vulnerability Zones demonstrates the importance of using soil information in decision-making regarding the formulation of site-specific soil use and management strategies.Peer Reviewe
