Response of Intertidal Areas to Historic Sea-Level Rise

The data suggest that vertical accretion on the intertidal areas of Blyth Sands/Yantlet Flats and Mucking Flats and the saltmarshes downstream of Gravesend has exceeded sea level rise over the past 30 years (Royal Haskoning, 2004). However, some areas of intertidal flat along the northern shore (e.g. Southend Flat) appear to have eroded over this time period. Overall, Blyth Sands/Yantlet Flats have vertically accreted at a rate of 4-5 mm per year between 1970 and 1998 (HR Wallingford, 2002a). Similarly, Mucking Flats has accreted by around 11 mm per year during the same time period (HR Wallingford, 2002e). Vertical accretion rates on saltmarsh surfaces have been measured up to 3.9 mm per year at Higham and 3.4 mm per year at Benfleet. Historic relative sea-level rise has varied between 1.22 and 2.14 mm per year (Woodworth et al., 1999) and as such, sediment availability to the estuary downstream of Gravesend is adequate to meet demand under current environmental conditions.

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