IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Role of sediment-flow feedbacks in the formation and self-maintenance of pool-riffle sequences
Role of sediment-flow feedbacks in the formation and self-maintenance of pool-riffle sequences
The traditional analysis of pool-riffle sequences considers them as static features of the stream bed, where the riffles are often idealised as weirs. A distinct hydrodynamic behaviour under low and high flow conditions can be used to qualitatively explain observations that most pool-riffle sequences present no drastic sediment erosion or deposition and are thus stable in the long term. Typically, during low flow conditions the riffles work as weirs and concentrate the higher bed shear stresses, whereas high flow conditions (floods) would drown the weirs and generate a migration of the higher shear stresses to the pools. This shift in shear stresses is a result of the interaction of the water surface profile and the shape of the cross sections at pools and riffles, and provides a cleaning mechanism for the sediment deposited in the pools. We often quantify the ability of a pool-riffle unit (i.e. a pool and the contiguous upstream riffle) to self clean as the shear stress reversal index p/r, where p and r are the bed shear stresses at the pool and the riffle, respectively. A value of p/r greater than unity guarantees self-maintenance.
File Size : 296,694 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 30/09/2015
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