Validation of an intrinsic groundwater pollution vulnerability methodology using a national nitrate database

The importance of groundwater for potable supply, and the many sources of anthropogenic contamination, has led to the development of intrinsic groundwater vulnerability mapping. An Analysis of Co-Variance and Analysis of Variance are used to validate the extensively applied UK methodology, based upon nitrate concentrations from 1,108 boreholes throughout England and Wales. These largely confirm the current aquifer and soil leaching potential classifications and demonstrate the benefits of combining soil and low permeability drift information. European legislation such as the Water Framework Directive will require more dynamic assessments of pollutant risk to groundwater. These results demonstrate that a number of improvements are required to future intrinsic groundwater vulnerability methodologies. The vertical succession of geological units must be included, so that non-aquifers can be zoned in the same way as aquifers for water supply purposes, while at the same time recognising their role in influencing the quality of groundwater in deeper aquifers. Classifications within intrinsic vulnerability methodologies should be based upon defined diagnostic properties rather than expert judgement. Finally the incorporation into groundwater vulnerability methodologies of preferential flow in relation to geological deposits, soil type and land management practices represents a significant, but important, future challenge.Original Abstract: La importancia de las aguas subterraneas en el abastecimiento de agua potable, y las muchas fuentes de contaminacion antropogenica, ha llevado al desarrollo del mapeo de vulnerabilidad a la contaminacion intrinseca de aguas subterraneas. Se han utilizado un analisis de co-varianza y analisis de varianza para validar la metodologia que se ha aplicado extensamente en UK basada en concentraciones de nitrato de 1108 pozos a traves de Inglaterra y Gales. Se confirma ampliamente las clasificaciones actuales de acuiferos y potencial de lixiviacion del suelo y se demuestra los beneficios de combinar la informacion de suelos y derrubios de baja permeabilidad. La legislacion europea tal como el Marco Directivo del Agua requerira evaluaciones mas dinamicas del riesgo a la contaminacion de agua subterranea. Estos resultados demuestran que se requieren varias mejoras en las metodologias futuras de vulnerabilidad intrinseca a la contaminacion de agua subterranea. Tiene que incluirse la secuencia vertical de las unidades geologicas de modo que