Author(s): Colin Thorne; Kevin Skinner; Gary Priestnall; Philip Soar
Linked Author(s):
Keywords: Flood management; Hawkcombe Stream UK; Hydrodynamic modelling; Sedimentation
Abstract: Until recently, flood management analyses and schemes often neglected to consider the implications of flood management for river sediment transfer systems. However, disruption of sediment dynamics in the fluvial system may have adverse impacts on flood defence infrastructure and in-stream habitats. In this paper, we report initial results from a project-centred study of the Hawkcombe Stream in Somerset, UK that was used to illustrate the nature of sediment-related problems and how they may be addressed. Two serious sediment-related issues are sedimentation in a culvert beneath the settlement of Porlock and degradation downstream of the weirs that mark the end of the flood defence scheme. Remedial works are now necessary to ensure that the flood defence functions of the culvert and channel are not compromised in the future. A qualitative Fluvial Audit was performed to establish the distribution of sources, transfer links and sinks in the sediment transfer system. Sediment transport modelling was then undertaken using the 1-D hydrodynamic model, iS IS, to provide advice on re-sectioning the culvert to allow it to transmit rather than trap coarse bedload.
Year: 2004