Landslide susceptibility analyses based on steady-state hydrological conditions and infinite slope stability model (Guneysu catchment area, Rize)

The aim of this study is to carry out landslide susceptibility analyzes based on steady-state hydrological conditions and infinite slope stability model. For this purpose, Güneysu catchment area located to the east of Rize in the Eastern Part of Black Sea Region of Turkey where shallow landslides are frequently observed in residual levels of magmatic rocks due to weathering was selected as the study area. The research was carried out in four stages; (i) firstly the national and international literature on the subject was evaluated; (ii) following the performing of the literature survey, the general characteristics of the study area were examined; (iii) additionally, detailed investigations have been carried out to produce shallow landslide inventory of the Güneysu catchment area; (iv) undisturbed samples were taken from the trail pits during the field studies; these samples were used to determine necessary mechanical and hydrological properties of the soils which are necessary for shallow landslide susceptibility analyses based on Stability Index Mapping (SINMAP). Geological, geomorphological and climatic conditions of the site were evaluated within the scope of the general characteristics of the study area. In the scope of aerial photo interpretation and field study; shallow landslide inventory, geotechnical site investigations and geophysical surveys were carried out. The samples obtained from the study area were examined within the scope of the laboratory study. In the last phase of the SINMAP model, landslide susceptibility maps were established after verification and calibration process, which was performed by using shallow landslide inventory. 12 different model studies were carried out considering that the residual soil levels evaluated in the analyzes performed may have infiltration capacity of 20%, 40% and 75%. Accuracy evaluations of the landslide susceptibility maps obtained as a result of model studies have been carried out. The correct estimation capacities of the models are calculated as 97.2% on average. When the variation of the stable areas with respect to different residual soil levels and different infiltration capacities is examined, the effect of the change in infiltration capacity is lost when the landslide susceptibility of geological material increases.