Assessment of Hydro-geochemical factors affecting coastal aquifer of Ghaemshar using by factor analysis and clustering

In this study, 26 wells in exploitation are used which corresponds to the average of two periods of minimum and maximum of (water table levels) from 2011to 2015, to detect controlling process and to determine the origin of groundwater ions. In this sample, the main ions, and nitrate with hardness and alkalinity, pH, EC and TDS are evaluated. In this study in factor analysis and clustering SPSS software is used, also in the cluster analysis ward’ method and Euclidean distance are used. The results of the factor analysis showed three components which control qualitative changes of groundwater in the minimum and maximum periods of water table have 83.5percent in minimum and 80.1% in maximum period in comulatative variance. These components are salinity, dissolution, and human activities. After clustering a determining the sub clusters, ion exchange, Gibbs and Piper diagrams are used to determine the chemical processes governing the aquifer of Ghaemshahr plain and their combined diagrams are depicted. In the Gibbs diagram, the weathering and evaporation and crystallization factors are groundwater chemistry controllers. In the Piper diagram, the type of water is mostly calcium bicarbonate and a small number of sodium chloride, mixing (Ca, Mg, and Cl), and last type is sodium-magnesium bicarbonate. This type of water is due to weathering and dissolution of carbonate sediments, the influence of salty water, and the leakage from saline aquifers that occurs due to ionic or invers-exchange processes along with chemical reactions. In general, three natural, non-natural, and mixing factors control the status of groundwater chemistry. The natural factors include the interaction between water-rock, salt water intrusion and evaporation from the surface of the water table. The Non natural processes (human activities) include the entry of urban sewage, industrial wastewater, and, agricultural effluent from various chemical types of fertilizers (nitrogen, sulfate and phosphate). The third process involves the increase of water level, the salt water intrusion, and advance in the aquifer, and evaporation from the water table resulting from excessive harvesting. This study showed that the use of multivariate statistical methods can be useful in analyzing the usual hydro-geochemical methods.