Limnetica 30

Fluvial morphology is conditioned by three basic elements: flow regime, sediment yield and valley characteristics. These elements are controlled by factors operating at different spatial and time scales, within and outside of the basin. Moreover, the great influence of human activities has to be considered as they presently constitute one of the main hydromorphological factors. This paper synthesises the effects of different variables on fluvial morphology and structures the review around the three basic elements mentioned above with examples from the Iberian Peninsula rivers. Understanding the factors that affect channel morphology is of primary importance for assessing river habitat condition, considering that river reach characteristics are the result of the interaction between upstream and downstream catchment and local conditions. Finally, fluvial geomorphology is a key element in river ecosystems that creates geodiversity and heterogeneity of fluvial forms at different spatial scales (i.e., river habitats) and should be considered part of our natural heritage and a valuable natural element itself.