Assessment of landslide susceptibility, semi-quantitative risk and management in the Ilam dam basin, Ilam, Iran

This research is focused on developing landslide susceptibility, risk andmanagement zonation map in the ilam dam basin, in the west of iran. forthis purpose, all existent landslide locations in the basin (50 landslides) wereregistered using gps device and 70% of these points (35 landslides) wereused for landslide susceptibility modeling and the rest (15 events) were usedto evaluate the model. in order to prepare landslide susceptibility map, eightkey factors were used for landslide occurrence such as distance to fault,distance to stream, distance to road, lithology, land use/cover, slope percent,aspect and precipitation derived from the spatial database in arc gis 9.3. ahybrid method of logistic regression and analytic hierarchy process (ahp)were respectively used to determine the weight and rate of different factorsand their classes. after applying rate to classes of parameters using the ahpmethod, landslide susceptibility map was prepared by means of logisticregression analysis tool in idrisi software. the model accuracy wasassessed by receiver operating characteristic (roc) indicator and the pseudo-r^2 and used as a basis for risk mapping. the landslide risk map was preparedusing varnes equation through combining three maps of susceptibility,vulnerability and the elements at risk. in order to provide the landslidemanagement map, multi-criteria evaluation (mce) method was usedincorporating susceptibility and risk variables. the results suggest the logisticregression and ahp model has high accuracy (roc= 81.2%, pseudo-r2=0.32). we found that 39.84, 72.45, and 76.33 km2 of ilam dam basinarelocated in the high and very high classes of lands lide susceptibility, risk andmanagement maps, respectively.