The arrested gravel front: stable gravel-sand transitions in rivers - Part 2: General numerical solution

Many rivers have an abrupt transition from gravel-bed to sand-bed morphology. In many cases the point of transition is neither prograding nor retrograding, but is rather arrested in place. Two mechanisms are hypothesized sized as responsible for stabilizing the gravel-sand transition, basin subsidence (or alternatively base level rise) and abrasion of gravel. The companion paper offers a simplified analytical solution for the long profile of a river with such a transition. This treatment allows for direct insight into the relation between the morphology and the controlling mechanisms at the expense of several gross approximations. The present paper offers a rigorous complete numerical solution which takes such facts as the streamwise Sorting of heterogeneous gravel into consideration.