Investigating the contribution of climate variability and land use change in water quality changes of Haraz River (Mazandaran Province)

To analyze surface water quality in the Haraz River, 12 water quality variables accompanied by hydro-climatologic parameters analyzed by Mann-Kendall Non-parametric test during the period of 1991-2015. To detect probable effects of land use changes, these changes also analyzed by GIS in 1991, 2006 and 2015 years. The results showed that most of time series of water quality have significant increasing trend that represents severe reduction in water quality of Haraz river. According to the results of Mann-Kendall test (trend analysis of hydro-climatic parameters, detection of abrupt change point and Kendall τ correlation test) and also land use changes trend, it was concluded that both climatic and land use change can be effective on reducing the quality of water resources so that temperature increase and precipitation decrease on one hand can be led to decrease of some parameters such as Ca2, HCO3- and TH, and on the other hand, these changes together with land use changes can be the main reason of increase in most of parameters such as TDS, EC, Na, Cl-, SAR etc.