Assessment of qualitative changes in Urmia quaternary plain groundwater

In this study, the quality of Urmia plain groundwater in 1380 and 1393 are discussed and analyzed. The main purpose of this study is to investigate the temporal and spatial changes in groundwater quality, mapping elements for the study time period and comparison of the elements in the waters with the region and international standards. Statistics of meteorological data as well as Urmia plain groundwater quality data, (20 sample wells), (1380-1393), are the most important data in this study. 1:25000 topographic maps and 1:100000 geological maps and GIS software are important used tools in this paper. The methods of study analysis are based on geostatistical methods and analysis of Wilcox, Piper and Schoeller graph. The results show that in 1380 the maximum of chloride is in the center of plains, but in 1393 the maximum amount of it, is pasted to east of plain (west margin of Urmia lake). In 1380, Sodium is high in the north, center and south but in 1393 some of these values is in the East and Northeast. Calcium ions in 1393 in comparison to 1380, has increased in east part of plain. In 1380 maximum bicarbonate ions (2.9) is seen in the west of plain while in 1393 maximum of this ion (2.10) has been seen in the eastern half of plain. The maximum electrical conductivity (EC) of groundwater in 1380 at about 1656 cm/ micromhos is in the center and northwest of plain. While in 1393 it was 2300 units and more can be seen in the east of plain. The total hardness of the water in 1380 from center of plain moved to the east of plain in 1393. In general, most of the elements during the study period in terms of time and place have changed. Despite the particular circumstances in the region, the quality of groundwater in the triple use especially in drinking use, is good.