Last week we looked at the impacts that beaches and transportation have on the coast.
Define the term: Berms
Name 3 different types of beach landform
What issues can arise from sediment transportation?
Given the different types of coastal management discussed so far it is your job to try out these methods given the materials at hand.
You will be writing a short report of no more than 350 words on the effects of coastal protection that you make. Some wood Gravel Sand Rocks Only use the gravel last. Design your protection and see how it works.
Set out each experiment describing how you went about it and what the outcomes were
Rank the different methods in terms of the following variables
Are there any other methods you can think of that would do the job just as well.
Include a field sketch of what you are doing.
Have you seen any of these?
controlled disruption of natural processes by using man-made structures.
Sea Walls – Hard Engineering
Highest protection in the short term, lifespan about 50 years.
Halts local erosion. They are very expensive to build.
Erosion continues where scheme ends, need maintenance .
Blackpool Sea Wall
Groynes – Hard Engineering
Groynes are designed to slow down longshore drift
The Build up of sand reduces the wave energy and thus protects the beach
They are usually made of tropical hardwoods which are more resistant to erosion.
A few are made of concrete, steel or in more recent times large rocks.
They are built at right angles to the shore and spaced about 50-100 metres apart. Groynes may have a life of 15-20 years
Groyne showing sediment depositation
Groyne showing protective effects
Terminal Groyne Effect
Occurs when there are piecemeal protection schemes.
For instance a groyne field is built and sediment builds up between the groynes
The coastline continues to erode.
On the downdrift side there is a sediment deficit. The erosion of non protected side continues
The unprotected down-drift shoreline is set-back landward compared to the protected up-drift shoreline.
Terminal Groyne Effect In Action
Revetments – Hard Engineering
A sloping feature which breaks up or absorbs the energy of the waves but may let water and sediment pass through.
The older wooden revetment consists of posts fixed into the beach with wooden slats between.
Modern revetments have concrete or shaped blocks of stone laid on top of a layer of finer material.
Gabions – Hard Engineering
A gabion is a metal cage filled with rocks, stacked to form a simple wall.
They are used to protect a cliff or area in the short term only.
They are easily damaged by powerful storm waves and the cages tend to rust quite quickly.
Gabions have the advantage of ease of use and are relatively cheap.
Rip Rap – Hard Engineering
Riprap (Rock Armour) consists of layers of very hard rock with the largest, often weighing several tonnes, on the top.
Riprap absorbs and deflects wave attack.
the use of ecological principles and practices to reduce erosion and achieve the stabilization and safety of shorelines and rivers, while enhancing habitat, improving aesthetics, and saving money
Soft engineering is achieved by using vegetation and other materials to soften the land-water interface, without compromising the engineered integrity of the shoreline.
Beach Nourishment - Soft Engineering
This is a technique used to restore an eroding or lost beach or to create a new sandy shoreline.
It involves the placement of sand with or without supporting structures along the shoreline to widen the beach.
It is the only management tool which serves the dual purpose of protecting coastal lands and preserving beach resources.
Cliff Regrading – Soft Engineering
Restructuring a cliff face to take away the steep gradient. reduces instability
What would be the most cost effective methods of protecting these coasts
Consider SMP’s for various areas on the coast and their effectiveness
Where does coastal erosion occur in the real world? Have a look at this map and think about the following questions:
Where on this map does coastal transport take place?