Effect of High Water and Water Scarcity Periods on The Quality of Surface Water Kashkan Basin

The alternative occurrence of high water and water scarcity in the basins is evident phenomenon. The occurrence of these periods in the Kasha's basin, addition to effect on quantitative condition of surface water, cause to changes in the quality of water in this basin. So, in this research using regression analysis in the soft ware’s environment Spss, Excel follow two main purpose. First, the study of relationship between high water and water scarcity periods with quality parameters of Kashkan basin’s surface water. Second, evaluating the surface water’s quality of mentioned basin for use in the agricultural and watering use during the high water and water scarcity periods. So, use the analyzed statistic of 12 parameters of water quality and daily discharge statistic of 8 hydrometer station in the rivers such as Dehno, Doab Aleshtar, Upper Kashkan, Khorram Abad, Middle Kashkan Cholhool, Madinrood, Down Kashkan in the 30 years (1351-1380) statistic periods.
Also flow continuity curve draw for each of mentioned rivers and extract the Q95 index as hydrologic drought threshold from this curve. The result show that in the majority cases, there is meaningful logarithmic relationship between high water and water scarcity periods with water quality’s parameters, and in the following of high water and water scarcity periods, the amount parameters of studied water quality in this rivers have upward and downward trend and lead to changes in surface water’s quality of this basin. Also, with evaluating the surface water’s quality of basin for agricultural and watering use indicate that in the alternative wet and dry period, the water of rivers such as Dehno, Doab Aleshtar, Upper Kashkan, Khorramabad, Middle Kashkan and down Kashkan has been among the good quality water and in the Cholhool and Madianrood rivers was acceptable and medium.