Landslide zoning and its risk management plan in Kohgiluyeh and Boyerahmad province using Haeri-Sami model

Introduction: In land use planning and sustainable development strategy, the selection and arrangement of land use options, project design and environmental management practices with legal and technical requirements are based on capability mapping and zoning of the severity and type of environmental hazards such as landslide and land instability. Landslide can be defined by mass movement of massive materials influenced by gravity and environmental factors such as earthquakes, floods and flood rains .This phenomenon has an effective role in destroying communication roads, residential areas and creating erosion and sediment in catchment areas. By zoning the risk of occurrence of landslide, it is possible to identify sensitive areas with high risk of land slipping and, by presenting solutions, appropriate control and management methods to some extent prevent landslides from occurring or reduce the damage caused by their occurrence. Landslide hazard zonation is in fact the division of the land surface into separate areas and the ranking of these areas based on the potential risk of landslide occurrence.
Methodology: In this research, the zoning of landslide hazard in Kohgiluyeh and Boyerahmad province has been done using the empirical Haeri-Sami method and the integration of thematic maps of rocks, slope angle, fault length, road and river length, rainfall, rainfall intensity and earthquake on a scale of 1: 1,500,000. After preparing of landslide zoning map, by carefully examining the images of Google Earth, areas of the province that were expected to have more potential for landslides were identified. Then, during extensive field observations, the geographic coordinates of the observed landslides were recorded and by providing the coordinates of the landslides in the Arc Map software and transferring them to Google Earth images, the location of landslides was identified and the respective area was prepared as a polygon file and transferred to the Arc Map software environment, and a digital map of the landslide distribution of the province was prepared. The Density Index (DR) was used to assess landslide hazard zonation map.
Results and Discussion: The results showed that only in term of geology about 40% of the area of Kohgiluyeh and Boyer Ahmad province has a high sensitivity to the occurrence of landslides, in the case of other factors such as slope angle, fault length, road and river length, rainfall, rainfall intensity and earthquake, about 95% of the area of Kohgiluyeh and Boyer Ahmad province has a small sensitivity to the occurrence of landslide. After integrating the numerical score of the thematic maps of the Haeri-Sami model, the landslide hazard map was prepared in four classes without danger, very low, low and moderate risk, with a distribution of area of 26.3, 33.8, 36.9 and 2 percent respectively. In relation to the evaluation of the performance of the model using the density ratio index, the results showed that the model has been able to distinguish between landslide hazard zones and are very accurate in the low risk class.
Conclusion: Based on the results of zoning, it can be said that the occurrence of landslide hazard in Kohgiluyeh and Boyerahmad province in the current situation is almost negligible and can only be managed by management plans for risk control or the principle of prevention, the occurrence of landslides in the province were prevented in the future. In general, for land risk management, there should be two components of the management tool and management method. The preparation of a hazard zonation map, the acquisition and use of the necessary techniques and training and promotion can be used as management tools and risk prevention, control and risk reduction in areas susceptible to landslide, can be considered as management practices. The results of this study are an effective step in planning and managing the land in Kohgiluyeh and Boyerahmad province.