JWSS - Journal of Water and Soil Science

One of the factors leading to the contamination of water resources is human activity, producing waste materials. In this paper, the effects of contamination on the water quality of Taleghan River, was simulated using of Qual2k model and the seasonal changes were evaluated. The qualified data collected during two months, August (as the dry season) and February (as the wet season), were used in the modelling. The results showed that the dissolved oxygen change was in the range of 4.5-6.52 mg/L in August. However, it changed between 4.8-5.3 mg/l in February and this reduction in the wet season was due to the run off deposition and the seepages of farmland near the river. Furthermore, BOD in the wet season and the dry season changed by 6-31 and 10-26 mg/l, respectively. These changes were due to the sewage dilution in flow during the wet season. Evaluation of the pH values in wet and dry seasons also showed that water of the river was more alkaline in the wet season, which is due to the effect of non-point resources or the fertilizer entrance after farm land bleaching by rain. Evaluation of Taleghan river EC variation also showed these changes were not significant during the wet and dry seasons. Water temperature was altered by 3-10⁰C and 19-25⁰C, respectively, in February and August.