Monitoring water quality and eutrophication phenomenon of Azad Dam using Iranian Water Quality Index and Carlson's Trophic State Index

Abstract

Water reservoirs are an important to the supply of drinking water and agriculture. In Iran, study of water quality in the dam has been considered in recent years. This study was conducted to determine water quality of Azad Reservoir (Kordestan-Sanandaj) based on Iranian water quality (IRWQI) and Carlson trophic (TSI) indices. Sampling was carried out at five stations during different months in 2015-2016. Results showed that mean (±SE) of NO3, NH4, TP, PO4, DO%, pH, EC, SDD, TH, BOD5, COD and Chl-a were observed 0.21±0.01, 0.048±0.004, 0.030±0.001, 0.016±0.001 mg/l, 114±3 %, 7.89±0.37, 290±40 µS/cm, 2.00±0.14 m, 138±1, 2.18±0.19, 9.28±1.13 and 4.73±0.73 mg/l, respectively. Result showed that trophic status of Azad dam was mesotrophic based on chl-a parameters and eutophic to hypertrophic based on other variables (TP, SDD, DO%) at bottom layers of some stations. Mean of Carlson trophic status was represented mesotrophic (high quality) at Azad dam. Based on IRWQI, water quality of dam was classified excellent quality. Although, mean of indices was suitable for drinking water and agriculture activities but due to decline water quality and increased trophic levels in some months, it is necessary to apply appropriate management strategies for maintaining of water quality of the reservoir.