A Coastal Hard Rock Sediment Budget for the Inner Bristol Channel

by A. T. Williams, Polytechnic of Wales, United Kingdom,
P. Davies, Polytechnic of Wales, United Kingdom,

Document Type: Proceeding Paper

Part of: Sediment Transport Modeling


The dominant input into the inter-tidal zone from the hard rocks bordering the inner Bristol Channel is clastic material. This is derived from coastal recession as a result of subaerial and marine processes. Recession rates, cliff height and outcrop length combine to give calculated sediment supplies of 50 × 103 m3 of Trias, 35 × 103 m3 of Jurassic and 42 × 103 m3 of Devonian derived sediments to the system. Gravels and muds predominate in the supply with only some 17 × 103 m3 of sand sized sediments arising solely from breakdown of Devonian rocks. Large scale sinks within the system have a 125 -200 year supply of clastic inputs. Sink volumes for the northern shore have been measured as 2.5 million m3. For the southern shore, site sampling gave values of about 900,000 m3 (Porlock) and 350,000 m3 (Blue Anchor Bay). Total sink volumes for the southern shore exceeds those of the northern shore.

Subject Headings: Shores | Coastal environment | Rocks | Sediment | Budgets | Coastal processes | Light rail transit | Sediment transport

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