Saving Teignmouth and Holcombe Beaches and maybe more of the GB coastline.
What is proposed here is to reduce the effect of sea storms on our coast - not tsunamis where the vertical end wave dynamic is astronomical and almost unopposable.
There are three options here that will protect the beaches and preserve some of the natural wave action that they have on those beaches
- A submarine breakwater made from concrete interlocking tetrapods
- Changing the sea bed parallel to the beaches through intermittent GPS focussed dredging and the production of a sand bar and deep water gulley distal seaward to this.
- Using underwater concrete to form revetments to absorb foul weather pounding
I think the concrete that is proposed to cover the beach would be better used to produce concrete tetrapods for a submarine breakwater running parallel to the beach. If the tetrapods are arranged in an intermittent manner in short lengths like this - _ - _ - _ - , it will reduce the power of the seas without abolishing altogether the waves that the beach enjoys and of course protect the beach and the cliff or bluff behind. The gaps will ensure that the marine life will quickly return. Quite often the tetrapods are used to reinforce existing breakwaters, coming well above the low water line and spoiling the view. I propose that their use here is kept well below this so there is no disruption of the view - it implies of course that there is adequate depth for this.
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Changing the sea bed is easily possible with the ability of dredgers to hover precisely through GPS and contour the sea bed parallel to the beach front forming a deep water runnel that will accommodate wave action and simultaneously use the sea bed removed to form a bar or soft breakwater on the beach side of the runnel. Again, marine life will quickly return afterwards.
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Slanted revetments can be made from UWC (or underwater concrete), again parallel to the beach front but arranged to allow partial transit of wave action. They can be designed to throw wave action laterally as well and thus direct thrust where or not it is needed to protect the beach head.
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All of these methods will preserve the aesthetic nature of the beach water front as well as the sands.
Tetrapods can be moved and thus their action can be altered to where best their action is needed. The technology for these in standard breakwaters is well known and it would probably be the quickest and cheapest to install. Gaps, as mentioned can be made large and marked for landing small craft or the RNLI. That these are made onshore and can be added to or adjusted makes them attractive.Their shape offers interlocking and stability and a large footprint spread on the seabed.
The effect of seas will build some sea bed up and around the pods and tend to reinforce their effect.
The beach and adjoining coastal seabed can be modelled on existing or new soundings and photographic data and used with historic weather information to generate what is likely to be a best outcome.
Success here might offer a formulae or algorithm for other threatened coastal features.
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