Statistical Analysis and Interpretation of Water Quality Data of the Vitens Well Fields

Abstract

The study area of the Water supply company Vitens is located in the northern and eastern part of the Netherlands. The company operates more than 80 well fields abstracting groundwater from about 880 wells. To carry out the main task of hydrochemical interpretation and to estimate the risk of environmental conditions to the groundwater quality in the capture zones of the Vitens well fields, chemical quality analyses of groundwater in the well fields were carried out and methodologies for statistical and hydrochemical interpretation procedures were designed and tested. Statistical methods such as cluster analysis and multidimensional scaling have been applied for the analysis and interpretation of the groundwater quality data. Initial statistics utilised the application of the Stuyfzand and Piper methods to obtain a first hand idea on the water types. Hierarchical cluster analysis was carried out for further classifying the water types in the study area. Thirteen components from the well samples namely pH, CH₄, NH₄, Fe, Mn, Ca, Mg, Na, K, HCO₃, Cl, SO₄, and NO₃, were used for this purpose. With hierarchical clustering analysis, the water samples were classified into 12 clusters. Cluster 1 and 3 contain the majority of the samples and were subdivided into 8 sub clusters. Multidimensional scaling and GIS Arc View have been applied to visualize the results of clustering in two-dimensional plotting. The results were used to cany out an intensive hydrochemical interpretation of the study area, which finally led to the formulation of 8 major and 3 minor water types.