Living with landslides: Land use on unstable hillslopes in a rural tropical mountainous environment in DR Congo

Abstract

Landslides are processes that naturally occur on numerous hillslopes across the world. In inhabited regions, landslides are commonly seen as a threat and a land degradation process. Yet, in densely-populated rural mountainous regions in the tropics, local communities have often no choice but to live on steep terrains naturally impacted by landslides. Besides, landslides may also be a source of opportunities for these communities. However, little is known on the rationale underlying land use in landslides. The aim of this study was to assess the extent, modes of valorization and degree of satisfaction of famers exploiting landslides in a populated rural mountainous environment of DR Congo (territory of Kalehe). We interviewed 82 farmers living on 57 representative landslides, these mass movements having been selected according to their characteristics (size, type) and position along the hillslopes and taking into account accessibility or safety constraints. We show that almost all landslides are being exploited by farmers and that they adapt their land use to the type of landslide. Indeed, significant contrasts are observed between landslides and the surrounding hillslopes for subsistence crops, forests, eucalyptus plantations and pasture. Farmers also adapt land use according to local variations in slope or wetness within a given landslide. Nearly half of the farmers reported that their land was more valuable inside than outside landslides. Better soil fertility, higher soil moisture, lower sand or stone content, lower slopes are some of the main factors that increase the land value, offering more favorable conditions for cropping than on land outside landslides. Despite the perceived risk of landsliding, famers settlement on unstable slopes appears justified by the immediacy of the benefits that outweigh the potential dangers. Better understanding the reasons for the settlement of populations on unstable slopes may help devise better risk reduction strategies.

Keywords: Africa; Mass movement; Perception assessment; Structured survey; Subsistence farming; Vegetation.