Knickpoints from watershed scale to hillslope scale: a key to landslide control and geomorphological resilience Knickpoints and landslide patterns
Résumé
The analysis of different geomorphic contexts in the Puy-en-Velay Tertiary basin (Massif central, France) reveals the importance of knickpoints in active landslide patterns at different spatial scales. At the watershed scale (mesoscale), landslides are essentially located downstream of knickpoints as a result of headward erosion dynamics driven by the incision of the river Loire and local base level lowering. At the hillslope scale, knickpoints illustrate morphostructural conditions and landslide dynamics, dependent on the elevation of the crystalline basement relative to the lowering of the hydrographic network. Hillslopes currently connected with the hydrographic network are still active, while disconnected hillslopes are fossilised. Finally, knickpoints can be considered as being strong discontinuities separating different geomorphologic units. The latter form as a result of variable adjustment tendencies to the base level (present or old) and consequently different hillslope dynamics. In short, knickpoints mark a limit between areas of different different hillslope dynamics. In short, knickpoints mark a limit between areas of different geomorphologic sensitivity and differ in their capacity for resilience.