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| Titel |
Numerical modelling of colmation and decolmation processes for gravel-bed river restoration schemes |
| VerfasserIn |
Alex Stubbs, Bettina Bockelmann-Evans, Thorsten Stoesser |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141867
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| Publikation (Nr.) |
 EGU/EGU2017-5419.pdf |
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| Zusammenfassung |
| It is well established that man has greatly influenced river sediment loading, which
has had a detrimental effect on the aquatic ecosystem, in particular on salmonid
spawning in gravel-bed rivers. Successful spawning relies upon a balance between
colmation and decolmation processes. Excessive colmation results in juvenile fish being
injured through abrasion and adhesion. Without decolmation, juvenile fish trying
to emerge from the riverbed, following their incubation period, become trapped.
Sediment oxygen demand and intragravel flows can also be influenced by colmation
and decolmation resulting in changes in dissolved oxygen levels in the riverbed.
Therefore, river restoration schemes often aim to emulate the balance between these
processes. However, though conceptually well understood, the physical processes of
colmation and decolmation are at best poorly described. This makes the design
of restoration schemes challenging and as a result many have had little effect on
salmonid spawning whilst some have even been detrimental. It is only with recent
advances in technology that it has been possible to understand the complexities of the
processes, in particular the influence of microscopic turbulent flows within the
near-bed region and within a riverbed’s pore matrix. This research aims to further
understanding of colmation and decolmation by focusing on the quantification of
turbulence close to and within the riverbed facilitating the modelling of these processes.
By enhancing the capability of the 2D numerical hydraulic modelling package
DIVAST (Depth Integrated Velocities And Solute Transport), this research ultimately
aims to improve the design and assessment of gravel-bed river restoration schemes. |
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