Assessment of Saltwater Pollution in Azarshahr Plain Groundwater, Iran: Conjugating GALDIT Method and Geostatistics

Abstract

Overutilization of groundwater resources can put their quality under stress. It could be base on rapid declination in groundwater level leading to salt water intrusion in the coastal aquifers. The objective of this study was to map the vulnerability of salt water intrusion of the Urmia Lake, Iran to nearby coastal aquifer (Azarshahr) using GALDIT method. The GALDIT index based on six parameters including; groundwater occurrence (<em>G</em>), Aquifer hydraulic conductivity (<em>A</em>), Level of water table above the sea level (<em>L</em>), Distance from shore (<em>D</em>), Impact of existing amplitude and extensive of saline water intrusion (<em>I</em>) and Thickness of aquifer (<em>T</em>) was computed in 21 observational points of the study area. A ranking system was developed both to give the relative importance of GALDIT factors and to differ categories within each GALDIT factor. After computing the GALDIT index for certain points, Geostatistic method was utilized instead of the layer overlaying to figure out the vulnerable zones. Results showed that except the central part of the study area and just 2 small portions in the northwest and southeast having moderate vulnerability hazards, others have a minimum vulnerability degree to the intrusion of Urmia Lake saltwater. Consequently, the GALDIT approach assisted to manage the monitoring of locations with high vulnerability risk.