Coastal Management

Coping with the Pressure

Today’s Aims are to:

• Look at the different types of management methods

• Distinguish between hard and soft engineering• Research the methods through trial• Consider management for schemes for various

areas

Review

Last week we looked at the impacts that beaches and transportation have on the coast.

1.Define the term: Berms2.Name 3 different types of beach landform3.What issues can arise from sediment transportation?

In Groups

• 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.

1. Set out each experiment describing how you went about it and what the outcomes were

2. Rank the different methods in terms of the following variables

- Durability

- Cost

- Effectiveness

3. Are there any other methods you can think of that would do the job just as well.

4. Include a field sketch of what you are doing.

The Management

Have you seen any of these?

Hard Engineering

• DEFINITION• 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.

Examples Southport

Southport 1948Blackpool 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

Examples

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.

Soft Engineering

• 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.

Example

Cliff Regrading – Soft Engineering

Restructuring a cliff face to take away the steep gradient. reduces instability

Plenary• 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?

• Where does the transport start? • Where does it end?

Today’s Objectives were to:

• Look at the different types of management methods

• Distinguish between hard and soft engineering• Research the methods through trial• Consider management for schemes for various

areas

Today’s Objectives were to:

Look at the different types of management methods

• Distinguish between hard and soft engineering• Research the methods through trial• Consider management for schemes for various

areas

Today’s Objectives were to:

Look at the different types of management methods

Distinguish between hard and soft engineering • Research the methods through trial• Consider management for schemes for various

areas

Today’s Objectives were to:

Look at the different types of management methods

Distinguish between hard and soft engineering Research the methods through trial• Consider management for schemes for various

areas

Today’s Objectives were to:

Look at the different types of management methods

Distinguish between hard and soft engineering Research the methods through trial Consider management for schemes for various

areas

For tomorrow’s lesson

• Find definitions for the following terms• Mudflat recharge

• Managed Retreat

• Shoreline management plan

• Earthbanks