Backwards-in-time river profile modeling: constraints on Dynamic Topography in the Western Highlands of Cameroon

We present a backwards-in-time approach for both linear and non-linear cases of the stream power (SP) equation to constrain uplift, erosional histories, and paleo-topography. Our approach does not assume that every source of change in a river profile can be accounted for. Instead, we use existing dynamic topography models, coupled with a backward-in-time erosion model and flexural isostasy, to focus on the large-scale perturbations affecting the river profile. This allows us to resolve best-fit dynamic topography models based on observed stream profiles. Here, we focus on the Western Highlands of Cameroon, a slow-eroding setting which is thought to have undergone large-scale topographic changes since at least the Miocene, due to its proximity along the enigmatic Cameroon Volcanic Line (CVL). We show that large scale perturbations (knickzones) in 3 of the largest rivers draining the highlands south of the CVL can be explained by up to 400 m of relative uplift due to dynamic topography over the past 30 Myr. These models suggest that a mantle source is largely responsible for recent uplift in the CVL region, as opposed to a purely lithospheric process suggested by others.