The evolution of sediment waves influenced by varyingtransport capacity in heterogeneous rivers

摘要

Large sediment inputs can cause pronounced variations in sediment storage and fluxin a drainage network and lead to deformation of alluvial forms and impacts on riverresources. Recent research has attempted to isolate this problem by focusing onthe evolution of individual sediment waves created by large point inputs. New one-dimensional models can predict streamwise variation of sediment transport anddeposition for engineering problems such as the fate of sediment released fromdecommissioned dams. Model predictions and supporting evidence from experimentsand field studies indicate that dispersion has a strong influence on wave evolution ingravel-bed channels. However, significant translation can occur where the inputmaterial is substantially finer than the ambient bed material, and streamwise vari-ations in channel morphology common to many natural channels can imprint reach-scale variations in storage otherwise absent in uniform channels. Three-dimensionalpatterns of erosion and deposition associated with sediment waves pose importantunsolved problems for the dynamics of alluvial forms and the effects on aquatic andriparian ecosystems.