Modification of GALDIT Model by using Entropy Method for Gharesoo-Gorgan Rood Coastal Aquifer Vulnerability Assessment

Document Type : Research Article


1 Msc in GIS/RS, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Assistant Professor, Department of GIS/RS, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran

3 Assistant Professor, Department of Irrigation and Drainage, Aburaihan Campus, University of Tehran, Iran


It is highly important to identify vulnerable areas and protect groundwater resources in the  Gharesoo-GorganRood coastal aquifer due to the overexploitation of groundwater resources in this area. Therefore, in this study, the GALDIT model and Entropy method in GIS environment was used to evaluate the vulnerability of coastal aquifer. The parameters of the type of aquifer, the aquifer hydraulic conductivity, the height of groundwater above the sea level, distance from shoreline, the qualitative impact of seawater intrusion, and thickness of aquifer were used in the GALDIT model, which influence the assessment of coastal aquifer vulnerability. The maps were arranged in the form of six information layers using ArcGIS software. To more accurately assess the vulnerability, the weights of GALDIT parameters were modified using the entropy method, and GALDIT-Entropy vulnerability map was obtained. The correlation coefficient between the TDS parameter and vulnerability indices in the study area was used to obtain the optimal model. The correlation coefficient between GALDIT-Entropy model and TDS parameter was obtained 0.51, while the amount of this coefficient was 0.43 for GALDIT model. According to GALDIT-Entropy model, the northwest, southwest and west areas of aquifer have higher vulnerability to seawater intrusion. The map of this model is classified into four vulnerability classes of low, moderate, high, and very high which compose 14, 33, 30, and 23% of the study area, respectively. The GALDIT-Entropy model reduced the errors from expert opinions in the initial GALDIT. The proposed method can be used to assess vulnerability in the coastal aquifers with the same hydro-geological conditions.


Main Subjects

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Volume 6, Issue 1
April 2019
Pages 41-50
  • Receive Date: 23 July 2018
  • Revise Date: 04 December 2018
  • Accept Date: 04 December 2018
  • First Publish Date: 21 March 2019