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Flood Hazard Research Centre, Middlesex University, Enfield EN3 4SF, UK
The northern coast of the Isle of Sheppey comprises actively-eroding cliffs up to 50 m high cut into the London Clay. From 1867 to 1998 the average cliff-top recession was about 1 m a–1, while the maximum recession was 1.9 ± 0.08 m a–1. From 1897 to 1998, this provided at least 4.5 x 105 t a–1 of fine-grained sediment to the Thames Estuary system and southern North Sea. This sediment input due to erosion is comparable in magnitude with fluvial sediment input from the Thames. The sinks for this material are unclear, but it is likely that the Essex and Kent estuaries and marshes have historically been important in this regard. Given climate change and accelerated sea-level rise, estuaries will again act as sinks, and it is prudent to maintain these supplies of sediment so that these estuarine systems can adjust to this forcing. To maintain sediment supply, shoreline management and estuary management needs to recognize more explicitly the importance and scale of fine-grained sediment supply and transport, including any implications for statutory land use planning.
