Assessment of factors affecting the intrinsic vulnerability of groundwater rated by the mean residence time estimation method

We analyse the factors used for assessing groundwater intrinsic vulnerability to pollution in the mean residence time estimation method, providing a final vulnerability evaluation. The following factors were analysed: depth to shallow groundwater, effective precipitation infiltration coefficient, terrain inclination, volumetric water content of soils and rocks in the unsaturated zone and volumetric water content of the topsoil. GIS surveys were performed for two geomorphologically diverse regions: a highland piedmont and a lowland plain in Poland (Central Europe). In both cases, groundwater had spatially diverse vulnerability to contamination. The research method used relied on determining the percentage participation of the area with particular values of the parameters analysed in areas of different degrees of vulnerability. Knowledge of the extent and distribution of variability of the parameters analysed in areas of particular degrees of vulnerability helps explain the causes of spatial variation in groundwater intrinsic vulnerability to contamination in given areas.