Landslide hazard zonation of catchments by using TOPMODEL and SINMAP models

In many civil engineering projects such as urbanization, road and dam construction, before designing and operating, the subject of landslide of the hillslopes, especially in the conditions of high rainfall, which may have financial and human damages, should be considered. TOPMODEL is a subsurface model used to estimate surface and subsurface runoff of watersheds based on the Dunny-Block mechanism. This model is capable of detecting catchment saturation area and estimating the soil moisture deficit (SMD) across catchment. There is a relation between the hillslope saturation index, which is a key parameter in landslide models, and SMD. In this study, the relationship between the two models of SINMAP (landslide model) and TOPMODEL and their parameters have been studied. For this purpose, the data of the ILAM Dam catchment data located in the southeastern province of ILAM in IRAN was used. The ten hillslopes of the area were taken to calculate the sliding. Using GIS, maps of SMD and index of saturation were calculated based on TOPMODEL, and finally, stability maps of SINMAP were calculated for the region. Hillslopes 3, 4, and 5 are quasi-stable according to the model, stability probability is less than 50% and stability probability is more than 50%, and in nature these hillslopes are unstable. The 8, 9, and 10 hillslopes that are used in nature from the vegetation of oak trees are stable, according to the model of these three hillslopes.