Long-term erosion rate in the SW Cameroon margin

The SW Cameroon margin within the Gulf of Guinea (2°–5° N and 8°–13° E) displays a complex landscape and crosscut by three active pre- and syn-rift structures: the Sanaga Fault, Benue Triple Junction and Cameroon Volcanic Line (CVL). We evaluated the erosion activity on this margin using for the first time the erosion rate quantification (ERQ). From the Digital elevation model (DEM, 30 m), we extracted compound topographic attributes (CTA), areal morphometric parameters (Ar) and differential tectonic drainage system (DTD) which were combined with field data and the following results were obtained: CTA indicates the relationship between erosion rate variation and the different forms of landscape, runoff diversity and sediments transportation under lithostructural (Precambrian basement and Cretaceous to Recent volcano-sedimentary cover) control. Ar reveals a variable erosion activity triggering sedimentation, denudation and landsliding referring to specific lithostructural units and landscape types. DTD underlines the control of the erosion activity in South Cameroon Low Plateau-, West Cameroon Highlands-, Coastal Plain morphological units and associated lithostructural domains. The stream power index (SPI) and the topographic wetness index (TWI) outline the erosion heterogeneity/variability and represent the key indicators of the state of erosion within the lithostructural units and landscape types. The ERQ, therefore, demonstrates the complexity of the SW Cameroon margin landscape as a result of long-term heterogeneous erosion applicable to South American, Asian and Australian Precambrian to Recent terranes.