Analysing riffle-pool dynamics of a large floodplain river with a system-oriented approach

作者：Vetter Thomas^*

来源：Zeitschrift fur Geomorphologie, 2011, 55: 355-372.

DOI：10.1127/0372-8854/2011/0055S3-0066

• Riffle-pool sequences
• velocity reversal hypothesis
• shear stress reversal
• bathymetric bedform survey

Investigations of a large floodplain river with a sandy, gravely bed and riffle-pool morphology were carried out to study the velocity reversal hypothesis. The river is divided into a reach with bed load equilibrium and a reach with bed load deficit due to an intermitted sediment sink. The resulting variability offers a good opportunity for analyses of the effects of sediment availability. A system-oriented approach taking into consideration bed form, bed material, and fluvial process, and integrating them by means of fluid mechanics is introduced.
Bathymetric surveys conducted during floods and bed material sampling formed the basis of the field investigations. Discharge data and geodetic surveys from external sources complemented the dataset.
Evidence is presented that a reversal of mean velocity or a reversal of shear stress did not account for the maintenance of the riffle-pool morphology in the study reaches. By contrast, dimensionless shear stresses appear to explain much of the differences in bed material mobility of riffles and pools because this approach takes into consideration the effects of bed material size. Significance and transferability of the approach to other fluvial systems is promising mainly because the approach is complementary rather than contradictory to other studies and hypotheses.

• 出版日期2011-4