Study on water quality of the Balighli-chai and Ghare-Sou Dareh Roud Rivers using the biotic indices of aquatic invertebrates and Iran's water resources quality index (IRWQISC)

Balighli-chai and Ghare-Sou Dare Roud rivers are the main rivers of Ardabil Province in Iran which have had considerable alterations due to climatic changes and high-water withdrawals. The present study was planned to assess the water quality condition of these rivers based on the presence and abundance of the aquatic invertebrates macrofauna and Iran's water resources quality (IRWQISC) indices. The levels of abundance, Shannon-wiener index, Simpson's diversity index, FBI index, and IRWQISC were calculated in Fall 2018 for 18 stations along with the rivers. 12 families of aquatic macrofauna were identified in samples, with the highest abundance for Baetidae and Chironomidae and the lowest abundance for Asellidae. The levels of the Shannon-wiener index were between 0.4 and 0.6 for most of the sampling stations. The Simpson's diversity index had values between 0.3 and 0.6 for most of the sampling points. FBI index values for sampling points were in the fair to very good classes while the levels of IRWQISC showed relatively bad to bad conditions. Generally, the results indicated moderate water quality conditions for the studied rivers, which further revealed an urgent need for educated planning strategies to improve the ecological health conditions of these riverine ecosystems.