Evaluating groundwater level and water-quality variation in Oshnaveh–Naqadeh Plain, Urmia Lake basin, northwestern Iran

Abstract

The groundwater depth and water-quality deterioration were evaluated at the Oshnaveh–Naqadeh Plain southwest of Urmia lake basin. During the 16 years from 2000 to 2016, groundwater levels dropped 3–16 m in the Naqadeh plain. In western parts of Oshnaveh, groundwater levels dropped about 16–25 m. To detect the reverse relation of water level and water quality with digging of wells or over exhausting of water, EC and SAR of the 78 wells located at the western parts of lake have been investigated, The exponential kriging generated a better spatial zoning of EC and SAR variation map of groundwater at two studied periods between 2000–2004 and 2012–2016. This study indicates that the higher values of EC more than 3000 µm/L are concentrated at the southwestern border of Urmia Lake. The spatial zoning of SAR map of groundwater values was higher in these wells than in others. The land-use map showed about 70% of this area is used for horticulture and agriculture; these lands are exposed to Urmia Lake salinity and water-level variations, the water quality in the wells of these parts is in poorer condition. The trend line of the slope of water quantity is negative, which implies that the situation of the lake and the water quality and quantity in the basin are worsening.