Evaluation of Land Sensitivity Potential to Subsidence Phenomenon using PCSM Method and Shannon’s Entropy Theory (Case Study: Abarkouh Plain)

The goal of this study is to prepare the potential map of subsidence in Abarkouh plain. For this purpose, data of 34 piezometer wells and 77 logs were used. Five factors affecting the subsidence include groundwater level, lithology of the aquifer, land use, aquifer thickness, and the thickness of the clay layer were selected and with Point Count System Model (PCSM) using, each study points leveled and their raster layers prepared with using Kriging interpolation. According to the importance and effect of each studied parameters in the occurrence of the subsidence, the weight of each layer was calculated using the Shannon’s entropy theory. Then, the raster layers multiplied by weight of each parameter and combined together, and the potential map of the land subsidence was obtained. Finally, in order to investigate the accuracy and validation of the produced map, the results compared with the land subsidence map that obtained from Sentinel -1 radar image. The results of the land subsidence potential map (PCSM method) showed that the eastern, northern and northeastern regions of the study area had the highest potential of subsidence. Besides the groundwater table drawdown, these areas contain clay with considerable thickness. According to the Shannon entropy theory, the thickness of the clay layer had a maximum effect on the subsidence occurrence. The comparison of subsidence potential map with the subsidence map that extracted from radar images showed the high efficiency (R=0.87) of the method that used in the present study.