Assessment of alluvial aquifer intrinsic vulnerability by a generic DRASTIC model: a discussion on data adequacy and pragmatic results

DRASTIC is a model that commonly used to assess vulnerability groundwater contamination at the landscape scale. When sparse data are available populate layers of model, it can be difficult ascertain true usefulness produced map. In this research, an alluvial aquifer in Kermanshah province western Iran was mapped using generic model. The for populating were generally sparse. validated nitrate concentration map constructed from well water measurements within area. Based on collected and analyzed, range values 107 177 found. Therefore, final divided into only two classifications, moderate high, instead normal five classifications typically used. results showed there no significant relationship with by statistical methods. However, field conditions method have good accuracy. Field evaluations karst recharge acts as factor diluting concentrations. Evaluation all classification methods (generic DRASTIC, natural breaks (Jenks), equal intervals, quantile, geometrical interval, fuzzy classifiers) based cross-validation, most consistent classifier one 62% quantile second place 36%. Changing weights rates justify measured concentrations does not show inherent nature contamination. emphasize use correct study before any optimization. addition, if optimization performed, necessary add layer or relate those factors having greatest impact pollution dilution ionic content obtained concluded produce reliable result, useful planning reduce potential, particularly vulnerable areas.