Detection of climate change and its impact on the trend of water quality in Kamal Saleh dam basin

Climate change and its impacts on water resources have been proven. In order to detect the phenomenon of climate change, this study firstly analyzes the time series of temperature and rainfall in the Kamal Saleh dam basin. The temperature and precipitation data of the basin area stations were investigated in the existing time period. For this purpose, the randomness analysis, turning points and autocorrelation tests as well as trend tests including parametric test, linear regression and nonparametric tests, Man-Kendall and Spearman’s Rho, were performed in a seasonal time steps for each station. Also, the minimum and maximum annual temperatures were analyzed. In general, the rejection of assuming the randomness of temperature time series in some stations and the existence of trends in most of them, as well as the trend of decreasing winter precipitation and increasing summer precipitation can be inferred as a reason for the existence of climate change in the study basin. In the following, the impact of climate change on the quality of surface water of the basin were studied. To do this, the trend of water quality components at Tire Doab station during the fifteen years period was analyzed by statistical tests for spring and winter seasons. For amounts of K, Na, Mg, Ca, SO4, Cl, HCO3 in water, a significant trend at 90% confidence level was observed. The amount of EC had an increase in spring but not significant and showed a significant trend at 95% confidence level in winter. TDS showed a significant trend at 95% confidence level. These results indicated the potential impact of the climate change on decreasing water quality.