Zoning the Rate of Pollution in Domestic River Using Spatial Multi - Criteria Evaluation Model

Surface water, especially rivers, is the most important sources of water supplies for drinking, agricultural and industry use and livelihoods. Controlling the pollution of BalikhlouChai River as one of the most important sources of water supply in Ardabil province in Iran is very significance and vital. In this research, the pollution zoning by using the Spatial Multi-Criteria Evaluation (SMCE) model in BalikhlouChai River was carried out to evaluate the trend of changes in water index and other important parameters by considering the physicochemical, biological, socio-economic and cultural constraints. First of all six stations were selected in the study zone and the sampling was performed over a 12 months period, and then the average of obtained parameters was compared with the standard values of Department of Environment in Iran. The results showed that fecal coliform in most stations and BOD₅ in stations 4 and 5, and Nitrate in the stations 4, 5, and 6 were more than standard. Next, the related factors and criteria with the changes in pollution trend in river was identified, weighted and prioritized by the Analytical Network Process (ANP) model. Then the basic maps were prepared and the information layers were incorporated into the SMCE model. Finally, the zoning map of BalikhlouChai River specified in terms of pollution and river health in two contaminated and safe areas in the study basin. According to the results of this study, 3 zones for the safe and 3 zones for the contaminated areas in the study region of river basin were determined which respectively the numerical values of 1, 0.85 and 0.75 for the safe zones and 0.2 and 0.1 and about zero values for the contaminated zones were calculated. The results of quality and quantity zoning indicate that the northeast regions of the study area, including Ardabil City outlet and the Qarasu River basin have gained almost zero value.