Efficiency assessment of two Information Value and Gopta-Joshi methods in landslide hazard mapping in the Talkhab watershed of Ilam
2011
Naderi, F., Geomorphologist, Teacher of Ilam Payam Noor University, Ilam | Haji Karimi, Staff Member of Ilam University, Agriculture Faculty, Ilam, Iran
Distinguishing the susceptible areas to landslide using appropriate experimental models of landslide susceptibility mapping is one of the primitive and basic works to reduce probable damages and reduce risk in country watersheds. In this research, at first, nine factors including slope, aspect, elevation, precipitation, and distance from road, distance from fault, and distance from drainage, land use and lithology are identified as effective parameters in landslides occurrence in the studied area. After preparing these layers in geography information system (GIS), the landslide distribution map of the watershed was prepared using aerial photos interpretations and field studies. Then, landslide susceptibility mapping was performed with two methods including information value (WINF) and proposed Gopta-Joshi method (LNRF). Finally, in order to evaluate the efficiency and verification of the landslide susceptibility mapping and determine the suitable model for landslide hazard mapping in the study watershed, the Landslide index was used. Based on this index, the information value and proposed Gopta-Joshi methods respectively classified the 79.8 and 58.5 percent of occurred landslides in high and very high danger classes; therefore, the information value method is more efficient in landslide susceptibility mapping in the Talkhab watershed than the proposed Gopta-Joshi method. Among the nine effective parameters, the geology factor has the highest effect in landslide occurrence; because about 50 percent of landslides occurred in Quaternary sediments which are susceptible to landslide.
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