On the factors governing river morphology with a look on how rivers adapt to climate

Abstract

River morphology can be described at different scales: at the basin scale we distinguish the river network; at the reach scale the planform, the slope and average features, such as the width and bankfull water depth; at the cross-section scale the transverse variations of river bed topography; and at smaller scales we observe bedforms and sediment grains. What are the factors that influence the river mophology at the different scales? Does climate govern these factors and if climate changes, how does the river react?
This review addresses these important questions, focusing at the reach and cross-section scales. Important knowledge gaps are related to the channel width formation, a key factor for river morphology. Several predictors based on field data relate the equilibrium width to bankfull discharge, sediment size, vegetation and bank resistance. However, it is not clear if the river width also depends on the conditions at the start of the morphological process. An example are rivers that adapt their morphology after their water and sediment discharge regimes have been altered by an external factor, such as a dam of a change in climate. Does the morphology of these rivers depend also on their previous width?