Our coast is disappearing! What can we do? http://www.andrewdunnphoto.com/ Erodedcliffpacifica.jpg‎

There are a number of possible approached to coastal management: Rapid coastal erosion often poses a threat to the settlement, industry and recreation that has grown up along the coast and we often look to protect the coast from erosion through appropriate management of the coastal system. There are a number of possible approached to coastal management: 1. Building Structures to defend the Coast 2. Pre-planning 3. Do-Nothing

There are a number of possible approaches to coastal management Fivepolicies.jpg‎

Building structures Can be divided into 2 types Hard Engineering These solutions generally involve concrete, metal, stone and other hard wearing materials that are intended to stop erosion and take little account of the environment. Soft Engineering These methods try not to disrupt the environment and tend to be used where the environment is more important than say a town or road

A) Hard engineering 1) Groynes £10,000 each (wooden groynes) £1.5m each (rock groynes) What are they designed to do? Stop longshore drift But further down the coast this may mean that beaches are starved of sand and shingle What are they designed to do? Stop longshore drift But further down the coast this may mean that beaches are starved of sand and shingle

Expensive at £5,000/m Designed to stop erosion, but what landforms would that prevent being created? Would you rather go on holiday and see Old Harry or a sea wall? 2) Sea Walls Energy is reflected (not absorbed). Over time the energy scours the base of the sea wall undermining it, causing it to collapse

3) Gabions Small rocks, bound in place by cages absorb the wave energy and reduce erosion Much cheaper than sea walls £1000/m, but do you think they are attractive?

4) Revetments £1,000/m Open structure of planks absorb wave energy, but allow sand and shingle to build up beyond Are these attractive?

5) Rock armour or Rip Rap Relatively cheap £1,000/m, but considered environmentally ugly. When resting on sand and shingle they may be moved out of position by waves

What if anything could make a home here? Would you have these? Advantages They all manage to absorb the energy from the waves and so reduce erosion They are long lasting Disadvantages They are not environment friendly They are not pretty They are expensive What if anything could make a home here? http://en.wikipedia.org/wiki/File:11-8-07_riprap_photo.jpg

B) “Soft” Engineering How attractive do you consider these to be? Advantages & disadvantages? How attractive do you consider these to be? B) “Soft” Engineering Less expensive than hard strategies Longer term, more attractive and sustainable as they work with natural processes Overall soft engineering is less expensive, longer term, attractive and sustainable as they work with natural processes, causing less damage.

Advantages & disadvantages? 1) Beach Nourishment Sand and/or pebbles are brought in to replace material that has eroded away. Where do you think this replacement material has come from? It has been dredged from the sea bed. In some cases it is pumped onto the shore. Advantages & disadvantages? The beach is widened; how will this affect the energy of the waves? It will reduce the energy that the wave has meaning less erosion. Cost: £100/m/yr Advantages: Helps protect against direct wave attack and longshore drift. Disadvantages: Alters natural ecosystem and may cause damage to marine life. Must be repeated relatively frequently, thus costly over time.

Advantages & disadvantages? 2) Stabilising Sand Dunes Grasses are planted in the sand dunes to bind them together, holding them in place. Adv: Works in harmony with natural ecosystem; sustainable Disadv: can only be used where dunes already exist. Artificial dunes can be created, but these are not replenished and so do not last long. Footpaths may be designated. Why might this be? To reduce trampling of the dunes by people, which erodes them

Advantages & disadvantages? 3) Managed Retreat When the land by the sea is of low economic value it may be allowed to erode. In some cases this eroded material forms beaches which naturally protect the coast. Adv: Cheap and sustainable! Disadv: People lose homes, land and livelihoods

Soft Engineering solutions Advantages There are no direct costs apart from that of removing any defences already in place and maintenance costs are very low. Sediment flow is also restored to its natural state, beaches can be naturally replenished due to erosion of the coast, providing protection and the balance of the coastline returns. Disadvantages A certain amount of land will inevitably be lost including settlements, farmland and other property. Because of this, managed retreat is often not a socially acceptable plan and may invoke the need for compensation to land-owners. There might be a loss of archaeological sites and heritage.

How do these stack up? Advantages They are more environmentally friendly They tend to be cheaper They look nicer Disadvantages If they are trying to, they slow up rather than stop erosion It might be your house that gets sacrificed?

What do you think should be done here? http://www.bbc.co.uk/learningzone/clips/a-farm-is-threatened-by-coastal-erosion-at-holderness-east-yorkshire/3189.html

Why protect/manage the coast?: Case Study Holderness Coast Locally, rates of erosion have been up to 10-20m with waves biting coast away Over 30 villages have been lost since Roman times, erosion has been taking place for last 6000 yrs Holderness Coast is fastest eroding stretch of coastline in Europe – an average of 2 metres fall into the North Sea each year

Mappleton and Holderness Coast This what they are doing along this coast – and what they are not!

Why are the beaches thin and narrow? Chunks of coast slump down the cliff Soft boulder clay The beaches are thin because the material is carried away by longshore drift Thin, narrow beaches do little to absorb wave energy Holbeck Hall, Scarborough Why are the beaches thin and narrow?

A bit of revision

Do you remember what this is showing? Direction of swash Longshore Drift Do you remember what this is showing? There were 3 processes … E, T and D? Which are the arrows showing? What is the heap of pebbles in the corner showing? What are wooden fence-like things called? Why are they there? This picture is showing LSD – which is?

And this happens if the long shore drift is allowed to carry on Deposits and seed are caught behind the shingle bar and a salt marsh begins to grow The coast changes direction What is this feature called? It begins with S But the long shore drift carries on But the load gets dropped as the longshore drift looses power

What is the feature you can see on this map? http://en.wikipedia.org/wiki/File:East_Riding_of_Yorks_outline_map_with_UK.png It is called Spurn Head © Copyright Stanley Howe and licensed for reuse under this Creative Commons Licence.

This Spurn Head What 2 features can you see in the picture which might be helping the Head from moving on? What kind of engineering is each of them? What do you think is happening in the lower pictures? © Copyright Stephen McKay and licensed for reuse under this Creative Commons Licence. Crumbling sea wall   © Copyright Charles Rispin and licensed for reuse under this Creative Commons Licence.

This Spurn Head What is going on in the top picture? Is it working? This is a sculpture of a welder made from flotsam and jetsam What is the method of sea defence you see in the back ground? Flotsam fell overboard while jetsam was thrown deliberately © Copyright Stephen Horncastle and licensed for reuse under this Creative Commons Licence. Beach sculpture Spurn Point Sculpture of welder made from flotsum and jetsum on beach.   © Copyright Steve F and licensed for reuse under this Creative Commons Licence.

This Spurn Head What are items in the top picture called? Tangled Nets   © Copyright Stephen Horncastle and licensed for reuse under this Creative Commons Licence. What are items in the top picture called? What do you think has happened recently in the bottom picture? Storm damage to the road near the narrowest point on the peninsula. Looking North   © Copyright Paul Allison and licensed for reuse under this Creative Commons Licence.

This is salt marsh Can you remember where that forms on a spit? How does it get there? © Copyright Paul Glazzard and licensed for reuse under this Creative Commons Licence.

No Homework to talk about You have it already Have a great half term