Evaluation of water quality of the Anzali international wetland using TOPSIS method

Due to the vulnerability of water resources, quality control of surface water is one of the key issues in environmental conservation programs. In recent years, Anzali wetland has been exposed to numerous threats, including environmental pollutants. TOPSIS is an efficient and reliable way to assess the quality of water resources.

In order to evaluate water quality condition, Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO), temperature, pH, turbidity, Total Suspended Solid (TSS), phosphate (PO4-), nitrate (NO3-) and Fecal Coliforms (FC) were measured seasonally from 10 sites of Anzali International Wetland in 2014 and the water quality condition was estimated using TOPSIS method.

The highest BOD5, phosphate, temperature and fecal coliform were measured at station 8. Comparison of TOPSIS values in different sampling stations showed the minimum (0.339) and maximum values (0.689) at the stations 5 and 8, respectively. According to the result, the station 5 (Sorkhankal) had the best water quality condition and station 8 (Pirbazar) had the lowest one. Also, seasonal results of TOPSIS values showed that the maximum value was at spring (0.742).

Discharge of effluents from land uses, agricultural and industrial activities located along the stream, could be considered as important reasons for decreasing water quality. Our results showed that TOPSIS method was clearly able to demonstrate the qualitative changes of water resources, indicating a moderate water quality for Anzali international wetland