Evaluation and Analysis of Groundwater Vulnerability Using Empirical Orthogonal Functions and Cluster Analysis

DRASTIC is known as the most prototype models of groundwater vulnerability assessment. The DRASTIC constitutes from seven schematic parameters consisting: Depth to groundwater, Recharge to aquifer, Aquifer geology, and surface Soil texture, Impact of vadoze zone and hydraulic Conductivity. In this study the models parameters were extracted by the main schematic maps of model. Instead using the linear combinations of parameters by the proposed weights of model, a principal component analysis (PCA) also known as empirical orthogonal function, was taken into account for assessing a more reasonable and accurate value for aquifer vulnerability. The advantage of this approach is accurate derivation of model weights and consideration of the maximum model parameters variances affecting groundwater system vulnerability. In the current study the models parameters evaluated for Qorveh-Dehgolan aquifer and the groundwater vulnerability of this site assessed using PCA. Eventually the first component (PC1) scores clustered using different Clustering Analysis (CA) and the best method delineated by Dunn cluster validation technique. PCA Results showed a large value of variance justification by PC1 equal to 72.5 percent. Also Dunn validation technique delineated the Single method as the best clustering manner.