Common assumptions in landform models
Change in landform shape from single event is small -- continuous process assumption
Water flow as steady and uniform
Processes and materials are spatially and temporally uniform
Simplified boundary and initial conditions
Notes:
Many models of landform evolution share common simplifying assumptions. These include the assumption that the change in landform shape from single events is small. Therefore, even though most sediment transport and fluvial erosion occurs during floods, the long-term cumulative action of these floods is often assumed to be equivalent to the continuous action of a “representative” discharge. In some cases, however, it is necessary to explicitly treat high intensity events in an “event” framework. For example, modeling of the effects of debris avalanches on landform evolution will probably require such an approach.
Similarly, water flow in channels is often modeled as steady and uniform, but these assumptions may need to be relaxed for certain applications, such as understanding erosional and depositional processes on floodplains.
Often the action of processes and the materials upon which they act are often assumed to be spatially and temporally uniform, although random variability is another common assumption.
Finally, almost all models utilize simplified boundary and initial conditions, as will be apparent when simulation models of landform evolution are introduced later. One example of such simplified boundary conditions is that the lowering of base level occurs at a constant rate, so that steady-state landforms can develop.