Sediment transport capacity relations for overland flow

Nearly all physically based models of soil erosion and landform evolution include an equation for the sediment transport capacity of flow, yet the choice of relation varies from one model to another. This raises the question of the empirical and theoretical support for particular choices. We review descriptions of the effect of discharge and slope on sediment transport capacity of overland flow. A limited range of relations is defined for which there is strong theoretical and empirical support. Nevertheless, suggestions are made for improved experimental designs that further evaluate theories of sediment transport capacity and reduce uncertainty in its application to catchment modelling of sediment transport.