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Management Strategies: Coasts
Terms in this set (14)
Do nothing/ No Active Intervention
Let nature take its course; coastal erosion is not fought.
Advance the Line
Define a line in the seaward direction and build up to it by reclamation e.g. Beach replenishment
Managed Retreat/ Managed Realignment
Create a sustainable flood defence by recreating eroded saltmarsh and mudflat habitat. This is done by creating new defences further inland and allowing the existing defence line to breach and the land to be tidally inundated.
Hold the Line
Keep the coastline at its present position by maintenance and building as required e.g. groynes, gabions, sea wall e.t.c
Rip-Rap/ Rock Armour
Large boulders, of 10 tonnes or more, are used as a sea wall. The gaps between the rocks allow water through, which means that the energy of the waves is dissipated very effectively. It is important that the boulders are big enough to withstand being eroded themselves and therefore becoming part of the coastal system.
Wave-Return Sea Wall
Concrete wall designed to reflect wave energy back into the sea.
This is where rocks and boulders are encased in wired mesh. They absorb the energy from waves
A wall made either of concrete or strong wooden posts and planks. Extends from coastline down to low tide water mark. It halts longshore drift. Sand piles up on the side facing the direction from which longshore drift advances.
Beach nourishment is carried out in places where the sand is being eroded, or where a beach is an important tourist resource. Sand and shingle are brought to the new beach from elsewhere. Alternatively, sediments are dredged and pumped from one side of a groyne to the other.
Advantages and Disadvantages of Rip- Rap
Advantages: Cheap and efficient
Disadvantages: Unattractive, dangerous access to beach, costs increase when rock is imported e.g. Beesands, North Hallsands
Advantages and Disadvantages of Groynes
Advantages: Cheap? Retain wide sandy beaches and do not affect access to the beach. Maintain tourism.
Disadvantages: Beaches to the south of the defences are starved of beach material due to their affect on long shore drift e.g. Barton on Sea due to Bournemouth Groynes.
Advantages and Disadvantages of Wave-Return Sea Wall
Advantages: Provide excellent defence where wave energy is high, reassures the public and long life span.
Disadvantages; Expensive, can affect beach access, recurved sea walls can increase the erosion of beach material. High Maintenance.
Advantages and Disadvantages of Beach Replenishment
Advantages: Restores beach material to maintain tourism. Cheap, retains the natural appearance of the beach and preserves the natural appearance of the beach.
Disadvantages:Off shore dredging of sand and shingle increases erosion in other areas and affects the ecosystem. Large storms will require beach replenishment, increasing costs. Bournemouth has used beach replenishment, costing £4 million; built over period of a month (Dec 2006-Jan 2007).
Advantages and Disadvantages of Gabions
Advantages: Efficient, absorbs wave energy
Disadvantages: Not visually attractive; unnatural. Shorter life span than a sea wall.
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