mojtaba mojtaba

Land subsidence is a geo hazard that leads to slow or rapid decrease of ground level. Land subsidence presents a constant threat to the safety of surface infrastructures such as motorways, railways, power lines, and telecommunication cables. Arid and semi-arid countries like Iran are very susceptible to land subsidence phenomenon. Land subsidence has occurred in more of 300 plains of Iran, and Semnan Plain is one of the most important areas that face to this phenomenon. The purpose of this research was land subsidence susceptibility assessment using entropy model. In the first step, acquiring information about sixty-five land subsidence in the past was done. Twelve conditioning factors from different basic layers including topography, geology, land use, and ground water table were considered for modeling aims. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to assess accuracy of the Entropy model. The AUC for the entropy model was 0.715 that showed this model is acceptable for land subsidence susceptibility mapping in the Semnan Plain. Results of this research can help to policy makers and planners for environment and urban management and planning.

The landslides impose serious damages to the economy, environment and human throughout the world. Identification of areas susceptible to landslides is necessary to avoid risks. In This research for Landslide hazard zonation in sarkhoon karoon watershed have been used Shannon’s Entropy Index and Information Value Methods. For this purpose, at first, landslide locations were identified using satellite images and field surveys and then landslide inventory map was created for study area. In the next step, 10 Effective Factors in Landslide occurrence include altitude, slope, aspect, distance from road, distance from fault, distance from river, lithology, land use, stream power index, topography wetness index, Plane Curvature and Profile Curvature were identified and mentioned maps will be digitized in GIS. In order to determine the weight of factors used Shannon’s Entropy Index and to determine the weight of classes used Information Value. The final Zonation map in the five classes include potential risk of very low, low, moderate, high and very high were prepared. The ROC (Receiver operating characteristic) curves and area under the curves (AUC) for landslide susceptibility map were constructed and the areas under curves were assessed for validation purpose and its value ​​showed that the hybrid model has a higher efficiency (0.781) for landslide hazard zonation. Results showed that land use and distance to road factors have the greatest impact on landslides. According to the results of landslide maps 14.45% (11220.4 ha) of the area are ranked as very dangerous areas and 6.11% (4744.1 ha) as dangerous areas.The results of this research can help planners to choose favorable locations for development schemes, such as infrastructural, buildings, road constructions, and environmental protection.