LANSLIDE HAZARD ASSESSMENT: ACASE STUDY IN QALA DIZA AREA

Abstract

During the last decades, expansion of settlements into areas prone to landslides in Iraq has increased the importance of accurate landslide inventory and susceptibility studies. Landslide inventory map is the spatial distribution of the gravity–induced mass movement. Susceptibility mapping provides information about hazardous locations and thus helps to potentially prevent infrastructure damage due to mass wasting. This study aims to assess the localization and size distribution of landslides in addition to implement selected parameters to predict landslide susceptibility using remote sensing techniques in mountainous environments. The study area is located in the Qala Diza area, Kurdistan region (NE Iraq), within the Zagros Fold–Thrust Belt, which is characterized by the High Folded Zone (HFZ), the Imbricated Zone (IZ) and the Zagros Suture Zone (ZSZ). The available reference inventory includes 353 landslides (representing a cumulated surface of 35.38 km2) mapped from twelve QuickBird scenes using manual delineation. The landslide types involve rock falls, translational slides and slumps, which occurred in different lithological units. We first analyzed cumulative landslide number–size distributions using the inventory map. Then, twelve factors, mainly derived from a Digital Elevation Model (DEM) of Shuttle Radar Topography Mission (SRTM), as well as geological and environmental predicting factors were appraised. We used logistic regression approaches to determine the landslide susceptibility (LS). The areas under the curve (AUC) of the prediction rate curve (PRC) for the landslide susceptibility shows that the accuracy of the map is 85.15 %. The results indicate that the Hypsometric integral (HI) and the lithology are the more dominant factors that lead to detect the occurrence of landslides. We argue that the use of adequate morphometric parameters can increase the efficiency of landslide susceptibility mapping in other regions of interest.