Abstract

Gaveh-rood and Gheshlagh Rivers are the main branches of the Sirvan River. Zhaveh dam was built on this river, with the purpose of use in agriculture and industry. Determine the water quality and water pollution in the Sirvan River and predicting the trophic conditions of the Zhaveh Dam reservoir are important goals of this study before the operation phase of the dam. Sampling was done at 5 selected stations of surface water in the branches of the Gheshlagh and Gaveh-rood Rivers, as well as the reservoir of Zhaveh Dam location. In this study, 27 water quality parameters (such as physical variables, hardness, alkalinity, nutrient, and sulfate) were investigated. Comparing the data of the current research with different standards showed that only the nitrate was within the permissible limit, but other parameters from one to several times (especially organic nitrogen) exceeded the permissible limit, which indicates that the water is polluted and has bad quality in different stations (especially in stations 2 and 3 in Gheshlagh branch). Based on the classification of the Iran water quality index (IRWQI) and the Comprehensive Water Pollution Index (CPI), all sampling stations (except the upstream of Gheshlagh River, Station 1) were classified in the “very bad” group (class V) and severely polluted (CPI=2.01) classes, respectively. Based on the values of TN and TP, the area was classified as a hypertrophic condition. Therefore, it is recommended to improve the water quality of the river to reduce adverse effects and promote sustainable use of water sources.

Keywords: Water quality index, Pollution index, Trophic state, Sirvan River, Kurdistan