Spatial and Temporal Assessment of Water Quality Changes in North, Northwest and Southwest Rivers of Iran, Involving Multivariate Statistical Techniques and GIS

Surface water, especially rivers, is one of the most important water resources that play an important role in supplying water for various activities. The purpose of this study was to investigate the temporal and spatial variability of water quality parameters in three different basins, in terms of land use, at 50 hydrometric stations in 9 rivers in the period 1992-2015 by using multivariate and GIS statistical methods. In this study, factor analysis based on 10 qualitative parameters was performed to determine the most important parameters affecting the surface water quality of the study area. The results of Principal component analysis showed that the North, Northwest and Southwest basins have two significant main components with 82.38%, 79.86% and 81.60% of the total variance, respectively. Cluster analysis of hydrometric stations located in northwestern and southwestern regions was divided into two clusters and north into three clusters. In the cluster analysis, some stations in Aji Chay, Atrak and Zayanderood rivers had different water quality characteristics than other stations. These stations are located downstream of the rivers. Based on the pattern of mean water quality parameters in GIS and land use map, station 2 had the lowest values for most parameters.