Note to teachers This revision session looks at – how human activity, especially management, influences the geomorphic processes affecting coastal landscapes. the factors that need to be considered when deciding on the appropriate management strategy for any coastline a ‘mini decision making exercise’ where the ideas can be applied. There are handout sheets to accompany. (02.1 Coast management)

Distinctive Landscapes: Coasts and human activity Geography GCSE Revision Distinctive Landscapes: Coasts and human activity Learning outcomes To outline the methods used to manage coasts. To evaluate the methods in terms of their effectiveness and impacts on geomorphic processes affecting coasts To understand the issues that are considered when deciding on any coastal management strategy.

Geomorphic processes changing the landscape Human activity and the coast. We have looked at the geomorphic processes operating at the coast and how these shape the coastal landscape. Another major influence on the coast is human activity and this will greatly affect the geomorphic processes. Transportation Weathering Geomorphic processes changing the landscape Mass movement Erosion Deposition Garry - One could add “the 4 agents causing erosion on Earth are ice, rivers, waves and wind” This course just looks at rivers and waves as agents of erosion. Human activity includes settlement, industry, agriculture, tourism and coastal management. All these activities will affect the geomorphic processes.

Human activity and the North Norfolk coast. The North Norfolk coast has been described as the UK’s “most vulnerable coastline”. Some parts (e.g. Blakeney) are low lying and are threatened by rising sea levels and increasing flood risk. Some parts (e.g. from Sheringham to Happisburgh) are threatened by rapid coastal retreat. The soft rock geology, exposed coast and rising sea levels are increasing the rate of erosion. What are the possible strategies for managing the coast?

Coastal management. There are 4 broad strategy options: 1) Hold the line. Defend the coast where it is. 2) Managed realignment or retreat. A ‘re-drawing’ of the coast boundary. 3) No active intervention. Do nothing 4) Advance the line. Push the sea back. There are few, if any, examples in the UK. The management strategy for each unit of the UK coast is set out in a Shoreline Management Plan (SMP) - “a document which sets out a strategy for a specified length of coast taking account of natural coastal processes and human and other environmental influences and needs”. The various methods possible can be divided into ‘hard’ or ‘soft’ engineering.

How can the coast be defended? There are many actions that can be taken. Generally the actions can be divided into two groups - Hard Engineering These methods generally involve construction using concrete, metal, stone. They are intended to stop erosion and ‘hold the coastline’. Soft Engineering These methods try to work with the natural physical processes in an area, rather than building large barriers.

Examples of hard engineering

Sea walls are concrete walls that are curved to deflect the power of the waves. They deflect rather than absorb wave energy. They are very effective at preventing erosion. However, they are also the most expensive (approx £2.5 million per km) and the deflected waves often scour the base, undermining the wall. This can mean that the waves wash away the protective beach.

Rock armour/rip-rap are large boulders that are placed on the beach Rock armour/rip-rap are large boulders that are placed on the beach. They are effective in absorbing the wave energy and protecting the sea walls. However, they can be ugly and wave turbulence can wash away the sand and shingle beneath, undermining the boulders.

Off-shore breakwater (reef) are rock structures placed in the sea, parallel to the coast. They force waves to break before they reach the shore and so reduce their energy. Off-shore breakwaters are not very attractive and can also have big impact on the wildlife and be a danger to people.

Groynes are wooden (sometimes concrete) structures that stop longshore drift. They build up the beach by reducing the movement of material along the coast. A wide beach will then protect the land behind. However, groynes can increase erosion further down the coast by starving those areas of sediment. They cost approximately £5,000-6000 each and will last about 25 years.

Groynes Many coastal resorts build groynes to stop longshore drift and try to keep the beach in place. Why? The beach absorbs the energy of the waves and is an excellent protection against wave erosion. The beach is an amenity (asset) for tourism.

Revetments are wooden structures that break the force of the waves Revetments are wooden structures that break the force of the waves. This will cause the waves to deposit material rather than erode or remove it. They are cheaper than a sea wall. However, they will last only about 25 years. They are not very attractive and not really suitable for a tourist resort as they restrict access to the water.

Gabions are cages of boulders built into the cliff face Gabions are cages of boulders built into the cliff face. The small rocks help to absorb the wave energy. They are much cheaper than sea walls but they are very weak and not long lasting. They are not very attractive.

Examples of soft engineering

Beach replenishment/nourishment is when beach material is added to the beach. A wide beach is excellent protection as it absorbs wave energy. The added material provides a natural solution that does not disrupt the beach ecosystem. It is natural looking and difficult to tell that management is taking place. However, it can be expensive to keep transporting large amounts of beach material and will need frequent replenishment unless protected by other methods.

Managed retreat is when the existing coastal defence methods are deliberately removed or abandoned allowing the sea to flood inland. This method encourages salt marshes and wetlands to develop in the flooded areas, which then provide a natural ‘buffer zone’. It is relatively inexpensive where there are few buildings but is not suitable for highly developed areas. Land will be lost to flooding where managed retreat is the chosen option, which will make it unpopular with those affected e.g. farmers, land owners.

Hard or soft engineering – an evaluation Hard or soft engineering – an evaluation. What are the advantages & disadvantages? Hard engineering Soft engineering Advantages It works! It does protect the coast. Tends to be cheaper Looks more ‘natural’ and less impact on ecosystems Can adjust to rising sea levels Disadvantages Very costly May look unsightly and ‘unnatural’ May affect ecosystems Is not flexible to cope with rising sea levels It can make matters worse elsewhere on the coast May be unpopular with landowners who want their property ‘protected’. Comment. It doesn’t have to be an ‘either / or’ choice. Both strategies can be adopted. However hard engineering is often considered less sustainable, for the disadvantages mentioned above.

Question. How have human activities affected the geomorphic processes operating at the coast? Discuss with your neighbour – what would you write? Any examples will do as long as you explain. The number of examples will be dictated by the space and marks available. At many places human activities such as coastal management have greatly altered the natural processes. For example, … … sea walls are designed to stop the sea eroding the coast. Curved sea walls will deflect wave energy and limit the impact of hydraulic action and abrasion. …. groynes will stop the process of transport of beach material by longshore drift. Creating a wide beach causes wave energy to be absorbed and help to prevent further erosion. However, in both examples protecting one part of the coast will affect the geomorphic processes elsewhere. As erosion and longshore drift are reduced in one place there will be less sediment transported further along the coast, thereby making the processes of erosion more serious there. If this is a ‘case study’ question just make sure you give named examples from Norfolk where these actions have been used e.g. at Overstrand.

What protection measures are in use here? Groynes – to prevent LSD and create a wide beach, which will abosorb wave energy Rock armour / Rip rap – to break the energy of the waves. Sea wall – to deflect waves. Beach replenishment – to create a wide beach that will absorb wave energy. 20

What strategy - Hold the line? Do nothing? Managed retreat? What are the questions that need answering when deciding on the appropriate strategy? How serious is the problem? How fast? How many people or properties are affected? What could be done and how much will it cost? Is it worth protecting? Will the benefits exceed the cost? What will be the effects further along the coast, if action is taken? If it is protected, how long will it last? Is the action sustainable?

Deciding on the strategy. Before any strategy is decided there needs to be – An Environmental Impact Assessment. What will be the effects on the environment here and further down the coast? A cost benefit analysis. No action can be justified if the costs exceed the benefits. Is it sustainable? How long will the benefits last? Rising sea levels and a soft rock geology might mean that in the long term nature is guaranteed to win. Is it sensible to fight the inevitable?

A decision making exercise. Study the map below. The local authority is under pressure from 3 locations to protect the coast. However, limited funds means that only one location can be protected. Which one would you recommend and why? Note: The validity of your choice (and the marks available) is dependent upon the quality of the reasons you give. You must apply your geographical knowledge. Location 1: Blakeney. A small village of 5,000 people. The site is low lying and threatened by rising sea levels and increasing flood risk. Location 2: Sheringham. A small town of 15,000 people. The coast is made of soft, porous cliffs 20 metres high. The cliffs are rapidly retreating. Direction of longshore drift. Direction of longshore drift. Location 3 Sidestrand. A very small village of 2,000 people. The coast is made of soft, porous cliffs 20 metres high. The cliffs are rapidly retreating.

Arguments in favour of protection Arguments against taking action Location Arguments in favour of protection Arguments against taking action Verdict? Blakeney Flood risk is a ‘sudden’ hazard that threatens lives. 5000 people could be at risk Only 5000 people live there. The costs would probably exceed the benefits. LSD should continue to create a wide beach that protects the coast Sheringham A large town with valuable commercial activities (business, tourism). Many people and properties at risk. The benefits would outweigh the costs. Erosion is a ‘slow’ hazard. Lives should not be lost. Rising sea levels will increase rates of erosion and weathering. Sidestrand 2000 people could be at risk. Only 2000 people live there. The costs would exceed the benefits. Protecting this coast will reduce LSD and make the problem worse further south.

A decision making exercise. Study the map below. The local authority is under pressure from 3 locations to protect the coast. However, limited funds means that only one location can be protected. Which one would you recommend and why? Note: The validity of your choice (and the marks available) is dependent upon the quality of the reasons you give. You must apply your geographical knowledge. Blakeney. Is action cost effective? Decision – Install flood warning system and recommend long term managed retreat. Location 2: Sheringham. A large community too valuable to abandon. Decision – Hold the Line (review in 50 years time) Direction of longshore drift. Direction of longshore drift. Location 3 Sidestrand. Is action cost effective? Decision: No active intervention and long term abandon this area .