Evaluation and Zoning of Groundwater Vulnerability by Using Geostatistics and GIS Methods (Case Study: Grapevine Gardens in Malayer City)

Groundwater is an important part of the ecosystems renewable water. Therefore, reducing groundwater quality is a major threat to agricultural development, especially in arid and semi-arid regions. Suitable application of pesticides in agriculture as not to contaminate groundwater, It requires understanding how these pollutants are transferred to groundwater and assessing the vulnerability of groundwater to pesticide contamination. In this regard, in the present study, the vulnerability of groundwater to pesticides in Malayer vineyards, was assessed in three scenarios of vulnerability in normal, unconventional and optimal conditions using three indicators: GUS, RF and AF. For this purpose, 9 pesticide, Diazinon, Malathion, Dursban Or Chlorpyrifos, Confidor Or Imidacloprid, Dimethoate, Linuron, Fenvalerate, Metsulfuron and Propargite Was studied. Also, zoning maps were prepared using kriging method in GIS software. In the first scenario, Koc and conventional t1/2 pesticide values were used. Also, vulnerability in the other two scenarios was assessed as vulnerability in the worst conditions and vulnerability in the best conditions.Then, according to the regional values of different indicators, pesticides ranking was done by combined programming method. Finally, by combining the results, the pesticides were divided into three groups of suitable, intermediate and inappropriate. The results showed that the probability of vulnerability is low in the northern parts of the study area and the southern part has the highest probability of vulnerability. According to the GUS index, most of the area is in the middle class in terms of leaching. Also Fenvalerate, Linuron and Metsulfuron pesticides were evaluated suitable for study area.  Key words: Groundwater vulnerability, GIS, Pesticides ranking, Composite planning, Vineyard gardens