An Overview on the Landslide Susceptibility Assessment Techniques

Natural disasters and their consequences have considerable and destructive effects on human life, properties, infrastructures, and, of course, on environment. One of the most important natural hazards, landslide plays a very important role in these effects throughout the world. Therefore, many countries, particularly the developed ones, invest huge amount of money either in mitigation or in prevention of landslides. The first, and probably the most important, stage of mitigation and/or prevention efforts is to assess landslide susceptibility by obtaining data related to landslides, i.e. preparation of landslide inventory and database. If taken into consideration, results of these assessments, i.e. landslide susceptibility maps, will provide useful information and economic benefits for urban planning, development plans, engineering applications, land use potential planning, and so on. When international scientific literature related to landslide assessments is examined, there has been an increasing interest in landslide susceptibility mapping studies in the last decades, instead of evaluating hazard and/or risk. Particularly, in recent years, depending upon the breakthroughs in computer technology, GIS (Geographic Information System), and RS (Remote Sensing) techniques, very important developments were achieved in these studies. This can be concluded as one of the most promising efforts with respect to combat with natural hazards since they opened wide range of opportunities for analyzing, evaluating, and assessing earth processes, notably for landslides. Thus, there are a multitude of studies carried out by different researchers in different parts of the world with the aid of these technological items. In this study, it was aimed at assessing landslide susceptibility techniques by means of a detailed literature survey based on an overview including twenty years' experiences. The techniques were categorized into two distinct groups such as qualitative and quantitative ones, and briefly examined individually. By doing so, a historical development of the techniques and actual trends in landslide susceptibility assessments were evaluated. It was revealed that some traditional methods seemed to have disappeared, while the new ones, particularly included in the GIS software, became very popular. However, at present, there seems to be no agreement on these techniques which can be the most effective one among the researchers.