Abstract
The diffuse nature of nitrate pollution makes it difficult to evaluate existing or planned measures to reduce it. Tools are therefore been developed to assess this pollution, ranging from simple indicators to complex models. The aim of this paper is to compare indicators and models by analysing results obtained from their individual application to the same area. The pros and cons of each approach are evaluated in terms of both the conditions of their implementation and the results obtained. This comparaison helps to guide the choice of a methodology. Rules governing data that choice are set in relation to the nature of the diagnosis to perform and the characteritics of the area under study.