GROUNDWATER VULNERABILITY ASSESSMENT TO PESTICIDES AND THEIR RANKING AND CLUSTERING

n this study, the different methods for groundwater vulnerability assessment to pesticides contamination and their uncertainties were introduced. Then, the groundwater vulnerability of agricultural regions of Pasha-Kolaa dam (Mazandaran province) to 7 pesticides has been assessed by the mobility potential indices in the typical conditions of pesticide properties (t 1/2 and K OC) and the zonation maps of groundwater vulnerability in this region have been generated in the GIS environment. According to the uncertainty of the pesticide properties and the lack of necessary data for uncertainty analysis in the region of study, the mobility potential indices in different scenarios of pesticide properties (worst and best conditions of pesticide properties) (t1/2 and KOC) have been calculated, mapped and zoned. The zonation maps in three scenarios (best, typical and worst conditions of pesticide properties) were compared. Next, according to the regional values of mobility potential indices, generated for different scenarios, the pesticides are ranked using the composite programming method. Finally, the pesticides are clustered to three groups (suitable, transitional and unsuitable) by the combination of the results of previous sections. The clustering results showed that among of studied pesticides, 2,4 D Acid, Dimethoate and Fenvalerate are suitable ,and Metsulfuron and Triclopyr are unsuitable pesticides for region of study. The other pesticides showed transitional condition.