Comparison of physicochemical and biotic indices to determine water quality in Jajrud River, Iran

Aquatic organisms are currently used as bio-indicators to determine the water quality of rivers in many countries. In this study, the results of Karun Macroinvertebrate Tolerance Index (KMTI) as a bioindicator and Revised Iranian Water Quality Index (RIWQI) as a physicochemical index were compared to evaluate water quality. For this purpose, water and benthic macroinvertebrate samples were collected from seven stations in four seasons in 2019. According to the RIWQI and KMTI index values, water quality at the stations was evaluated between 37.21 to 75.98 and 2.9 to 6.21, respectively, falling into poor, medium, and good categories. In this study, KMTI index had a significant correlation with RIWQI index (p<0.01). Also, both indices had a significant correlation with total dissolved solids (TDS), oxygen saturation (DO%), biochemical oxygen demand (BOD), nitrate (NO3), phosphate (PO4), turbidity (NTU), and fecal coliform (p<0.01). The values of KMTI index declined when these water quality parameters increased, which can be caused as a result of the parameters' impact on decline in sensitive species. The obtained results from KMTI and RIWQI indices demonstrated that tourism activities, restaurants, industries, and residential areas imposed a surplus of environmental burdens in some parts of Jajrud River. Therefore, river basin management must be implemented to rehabilitate the impacts due to human manipulation, improve the water quality, reduce public health risks, and proceed toward sustainable development.