Comprehensive Assessment of Surface Water Quality and Their Suitability for Drinking and Irrigation Uses (Case Study of Karun and Dez River Basin)

Sustainable quality of rivers water has become one of the main concerns in developing countries, so monitoring the water quality of these resources for various uses is essential to formulate a public health and environmental management policy. The purpose of this study is to evaluate the water quality of Karun and Dez river systems in Khuzestan province and to analyze the suitability of their water quality for drinking and agricultural purposes. To this end, various techniques, indicators and statistical analyzes are used to evaluate spatio-temporal changes in the interpretation of large and complex datasets of 12 water quality parameters collected from the Karun and Dez river basins over a period of 17 years (2003-2019).Evaluation of the trend of water quality changes in the study period also showed that according to WQI, the water quality of Karun and Dez rivers from 2003 to 2007 are in the category of "very poor"and "poor", and from 2008 to 2018 in the "unsuitable" and "very poor"category, respectively. Regarding irrigation parameters, the lack of a clear trend in their values can indicate the lack of effect of river water quality from natural factors and their obedience with human factors. Overall, this study highlights the importance of using water quality indicators that provide a simple interpretation of monitoring data to help improve water quality, because based on these indicators and PCA, it can be concluded that related human activities along the banks of the Karun and Dez rivers, especially in recent years, affect their water quality.