By Robin Whittle
Several articles have been written in the Deben Magazine concerning the river wall defences1,2,3,4. This article concentrates on the immediate need for action on the river wall of Flood Cell 1: Bawdsey to Ramsholt.
The clay river walls of the River Deben have provided landowners and the local community with grazing marsh and arable land for the past five hundred years. During this time the walls have been raised by about 0.6m/century to compensate for sea level rise and clay wall settlement (see Figure 1).
Figure 1: River wall at Ramsholt being enhanced in 2015
Where breaching occurs, the wall is either eroded down to saltmarsh level or, where there is no saltmarsh, down to the embanked fresh-water marsh level. The latter is very difficult and extremely costly to repair, usually requiring the use of helicopters. Overtopping is not necessarily damaging to a wall providing the wall is largely level and the overtopping is less than 200mm over a landward slope of not less than 1:2. (see Figure 2).
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