Subsidence risk zoning in Varamin County based on effective criteria using TOPSIS and VIKOR techniques

Subsidence is a crisis that modern societies are currently facing. It has the potential to inflict irreparable damage to the lives and properties of residents, as well as disrupt urban infrastructure, including water, oil, and gas transmission lines. While horizontal displacement is also possible, its extent is typically minor. Subsidence results in the formation of cracks and fissures in the ground, alterations in underground water quality, changes to the Earth's surface topography, and other related issues.

In this study, using the multi-criteria decision-making approach, the seven criteria have been taken into account to produce subsidence risk map. At first, expert opinion on this issue have been used to investigate the effect of different criteria on subsidence. Then the weight of each criterion was obtained using the geometric mean method. Then to combine the layers, VIKOR and TOPSIS fusion techniques were used. To evaluate the implemented method, Sentinel 1 radar images were used to prepare a subsidence map, and a comparison between the two maps has been made.

The analysis indicated that land use, underground water, and rainfall had the most significant influence on subsidence, with weights of 0.4292, 0.2699, and 0.1473, respectively. In contrast, slope and elevation had the least impact, with weights of 0.0220 and 0.0375, respectively. A subsidence map was successfully produced using Sentinel-1 images and Differential Interferometric Synthetic-Aperture Radar (DInSAR) techniques, and this map was compared to those obtained through VIKOR and TOPSIS methods, demonstrating a favorable level of compatibility.