Assessment of drought and landuse changes: Impacts on groundwater quality in Shabestar basin, North of Lake Urmia

Management of groundwater quality is very important in arid and semi-arid areas. In this study, satellite images from TM, ETM and OLI sensors were used to evaluate the impacts of land use changes on groundwater quality for 1990, 2007 and 2015 in Shabestar basin. After processing and analyzing images, the basin was classified into five land use classes including pasture, bare land, farming, garden and residential. Motivate averages of 3, 5 and 7 years were used to determine precipitation changes trends and identifying wet and drought periods.  Zoning maps of qualitative parameters including EC, SAR, TH, Cl and Na for 40 wells in a decade (2002 to 2012) were plotted using geostatistical methods to evaluate changes in groundwater quality. The obtained results from motivating average graph showed that drought was occurred during the first period 1997 to 2003 due to lack of rainfall, the worst drought was occurred in year 1999. Overall, the quality of groundwater was improving over the period. So that water quality was low in the first period (2002-2005) due to coinciding with the drought period and water quality was improving due to coinciding with wet periods in the second and third period (2006-2009 and 2010-2012). The amount of water quality parameters has increased in the southern and western parts of the region where located in the vicinity of Lake Urmia and water in these areas aren’t suitable for farming and drinking. It can be due to overuse of groundwater affected by land use changes in this parts of the region.