Human–environment interactions in residential areas susceptible to landsliding: the Flemish Ardennes case study

Studies on landslide susceptibility and landslide risk generally start from the assumption that mainly natural factors control the occurrence of landslides. The role of human activity is considered less important. We investigated the role of human–environment interactions in the Flemish Ardennes, Flanders' most landslide-susceptible region. The establishment of a detailed landslide inventory brought insight into the spatial occurrence of landslides and into the different landslide types and characteristics. A statistical model, i.e. logistic regression, allowed the significance of environmental factors controlling landslide occurrence to be determined, and a landslide susceptibility map to be produced. Being a residential area, however, the Flemish Ardennes is a region where humans play an active role with regard to landslide risk. Although the location of many archaeological sites in this area is known, almost no archaeological sites are found on landslide-susceptible hillslopes. This might indicate that in prehistorical and historical times humans were more familiar with local environmental characteristics and avoided unstable hillslopes. Comparison of topographic maps (1777–2001), on the contrary, indicate that over the last 250 years buildings and other infrastructures have been constructed on old landslides. Given that humans are living, working and driving on or close to unstable hillslopes, the landslide risk has therefore increased. The landslide inventory map and the landslide susceptibility map are important tools for landslide risk reduction. Here ‘science meets policy’, as both maps allow linking construction norms and other mitigation measures to hillslopes already affected by landslides and to susceptibility classes with very high, high and moderate landslide susceptibility.