Water quality evaluation of Gazroudbar River using NSFWQI and Liou indices

Current information about the quality of water resources is highly important in preservation, planning and management of these resources. Gazroudbar River with a length of 61.73 km flows into the international wetland of Anzali. This study aimed to assess the water quality of this river by using and comparing NSFWQI and Liou indices. In this study dissolved oxygen, biochemical oxygen demand, pH, nitrate, temperature, total phosphorus, total solids, fecal coliform, turbidity, suspended solids and ammonium were measured based on “Standard Methods”. Sampling was done during 12 months (from September 2014 until August 2015) in five selected stations. The results of this study showed that the monthly average of NSFWQI index values were in the range of 50.4-60 and the monthly average of Liou index values were in the range of 1.1-3.85. According to the results of these indices, the first station had the best quality (NSFWQI=64.6, Liou=1.4) and the forth station had the worth quality (NSFWQI=49.25, Liou=3.73). According to the NSFWQI index, the water quality of the Gazroudbar River is within the category of medium (50-70) and based on the Liou index, the water quality is in the category of slightly polluted (2-3). According to the results, garbage dump, depletion of household, rural and urban wastewater, agricultural drain water, and animal waste into the river as well as a low river discharge are the main reasons to have an unsuitable water quality in the studied stations.