A new procedure to accurately define Nitrate Vulnerable Zones

1 ilustración: LU-IV procedure for assessing groundwater vulnerability to nitrate pollutionThe Nitrates Directive of the European Union (91/676/EEC) aims to reduce and prevent water pollution caused by nitrates from agricultural sources. It establishes that water resources should be considered polluted when nitrate concentration exceeds 50 mg L-1. The Directive requires the Member States to designate Nitrate Vulnerable Zones (NVZ), which are areas that drain into waters polluted or at risk of pollution by nitrates. InNVZ, farmers must follow mandatory measures within action programmes that include limiting N-fertilization and animal manure application to prevent nitrate leaching and runoff. One of the difficulties in implementing the European environmental policies for nitrate pollution control is the lack of a common standard criterion for NVZ designation, which in turn may limit the success of action programmes in poorly defined NVZ. Index-based groundwater vulnerability mapping has proven to be a useful tool to assist governments in establishing policies related to the planning of water resource management over the last few decades. There are still, however, research gaps in assessment techniques and scientific considerations behind the inclusion/exclusion of parameters and their relative weights and ratings. In addition, most methods for mapping groundwater vulnerability are based on the excessively simplistic idea that aquifer recharge is only produced by vertical infiltration. The Land Use-Intrinsic Vulnerability (LU-IV) procedure for assessing groundwater vulnerability to nitrate pollution and delimiting NVZ was recently developed to address the above-stated challenges