Lesson video

Hi there.

I'm Ms. Roberts, your geography teacher, and I'm here today to take you through this lesson, which is part of our unit, all about the coasts, investigating what happens where the land meets the sea.

Today's lesson is all about that land and how we can protect it.

By the end of the lesson today, you will be able to name and describe different methods of coastal protection and you'll be able to talk about their effectiveness.

That's how successful they are at doing what they were designed to do.

Let's begin by looking at some key words for this lesson that are going to be very useful for you to use and understand.

There are three key words that I would like you to use today.

They are static, flood, and energy.

Something that is described as static means that it never moves, it never changes.

It stays exactly as it is and it stays exactly where it is.

You may already know what a flood is.

A flood occurs when there is simply too much water for a waterway such as a river to hold.

When that happens, the water will overflow or burst out onto the surrounding land, which would normally be dry.

Energy.

You are probably familiar with energy.

Energy is power and it's the power that we use to make things work.

For example, to provide heat or light or to operate machinery requires energy.

We get our energy from the food we eat and that enables us to go about our everyday tasks.

There are two halves to this lesson today.

First, we are going to think about the reasons why our coastal communities need protection.

And then later we are going to think about what can be done to protect those communities.

You may already have some ideas about this yourself.

Let's make a start then and think about why it's important for our coastal communities to be protected.

In the UK, more than 8 million people live on the coast in coastal communities, but the coastline is not static.

It is always changing.

It's a very dynamic environment.

Look at the photograph of this coastal area.

What problem could be caused here by the fact that this coastline is constantly changing? Can you see here that there are homes very close to the cliff? You can see a building here that is dangerously close to the edge as this coastline is eroded and the coastline and the cliffs continue to retreat further backwards.

Without a doubt, homes and buildings such as this one are going to fall into the sea.

Our coastlines have been continually changing for many thousands of years, but this becomes a problem when these changes begin to affect people at the coastline, when there are dangers to their homes and their businesses.

There are an estimated 1.

8 million homes as well as around 140,000 businesses that are at risk of being destroyed due to coastal flooding or erosion in the UK.

Okay? This could potentially affect anywhere between four and 5 million people, so protecting our coastal communities really is a very important issue.

We're going to look at one small coastal community now as a case study, as an example of the need for protecting our communities.

This is a location called Happisburgh, which is a village on the North Norfolk Coast and the population there is approximately 1,400 people.

The coastline here in this area has been constantly eroding and changing for well over 5,000 years.

One of the main reasons why this coastline is constantly eroding is because of the geology of the area.

There are many cliffs along this coastline.

The cliffs are about 6 to 10 metres tall, so they're quite high, but they are made of very soft types of rock such as sand, silt, and clay.

Soft rocks like these are very, very easy to erode, unlike harder rocks such as granite, for example.

So let's think about what you now know about the geology of this area.

To answer a quick question, this is a multiple choice question about the cliffs in this area.

Pause the video now and decide which of these is the best reason to explain why the cliffs are so easy to erode.

Have you decided? The correct reason is because of the geology?.

It's because they are made of very, very soft rock like sand, silt, and clay.

So these parts of the coastline that are made of these soft rocks are very easy to erode.

Well done.

You may be wondering how we know that the coastline here has been changing for as long as it has and how can we measure or record these changes? One of the ways that we know about these changes is by looking at historical maps of the same place.

We have three maps here for you to look at of the Happisburgh region.

We have a map from the 1890s.

We have a map from the 1950s, and we have the current ordinance survey map of today, 2024.

We're going to look more closely at each of these three maps and compare them to see what differences we can discover.

What we're going to do is draw a line on each map at what we call the high water mark.

The high water mark is the furthest point at which the high tide reaches.

So that's the furthest point that the sea will come in towards the land.

The orange line on this map shows the high watermark as it is today in 2024, so you can see how that orange line hugs the coast.

It hugs the coastline all the way along.

Let's now look at the map from the 1950s and see where the high watermark was then.

Then red line here is the high watermark from the 1950s.

Look closely at these lines.

What do you notice? They're not in the same place, are they? What has changed since the 1950s? Well, we can see that the orange line is now much further inland than the red one was, especially in the area near the coast guard station.

We can clearly see that the coastline has been retreating.

If we move now to the map from the 1890s and do the same thing, let's see what happens.

The blue line here shows the high water mark as it was in the 1890s.

Where do you think that blue line is today? It's in the sea.

Today that blue line would be in the sea, but in the 1890s the water stopped at that blue line because that's where the land was.

If we put all three of those high water marks onto this one map from today, we can clearly see how far the coastline has eroded since the 1890s.

I've annotated the widest difference with these black arrows here, so you can see the huge difference from where the land was in the 1890s to where it is today.

Do you know that widest difference is actually 151 metres? That is longer than the length of a football pitch and all of that land has been eroded, crumbled, and worn away by the sea.

All of these processes of erosion are continuing to happen today, just as much as they were between 1890 and 1950.

Right up to today, these processes do not stop.

Recent statistics tell us that between 2003 and 2023, over that 20-year period, 34 homes had crumbled into the water at Happisburgh as a result of coastal erosion happening there.

All of that land that was destroyed between the 1890s and today could have had other homes.

It could have had businesses.

It could have been roads and transport routes, all of which was destroyed when the land crumbled into the sea.

Let's have a quick check at what we understand to be happening here now.

Izzy and Sam have been talking about what's happened in Happisburgh.

But whose explanation is the best to describe what's happening? Sam says that the people built their houses too close to the cliffs and so some of them fell down.

Izzy says that the coastline is eroding all the time that land eventually collapses into the sea, and this means that the homes which were built away from the coast are now a lot nearer to the cliff edge.

Which of those explanations do you think is the best reflection of the situation? Izzy's explanation gives us a better overview because the constant changing of the coastline makes a difference to the lives of people here.

It's that the coastline stays the same and they build their houses too close.

The houses weren't close to the coast.

It's the fact that the coast has retreated closer and closer towards the houses.

Let's have a quick activity about the coastal erosion that's happening in its area.

Here is an aerial photograph of the Happisburgh area today.

What we can see here in the photograph is a caravan park that is currently sitting on the edge of the cliffs there at Happisburgh.

You can see very close by to the caravan park.

We have some of the village buildings, including the local church.

What would be your prediction about what could happen here in this area in the photograph in the future? I've given some sentence starters to help you, and I've provided a word bank.

Try to use those words to complete these sentences to make your prediction about what's going to happen here.

Pause the video to complete the activity.

Ready? Well done.

Izzy's going to share her answer with us now.

She says that in the future, she thinks some of the buildings in Happisburgh may fall into the sea.

She thinks this because the coastline has been retreating there for thousands of years because the sea is eroding the cliffs.

Did your answer include similar ideas to Izzy? Well done.

So we know that there's a lot of risk.

We know that home businesses, roads, other transport routes, caravan parks can all be lost to the sea.

So now what can we do about it? Let's find out in this second part of our lesson.

Everything that we find at the sea is at risk because of erosion.

That includes the homes, businesses, roads that we've mentioned, and it also includes animal habitats, historic sites, and other places along the coastline.

Currently, in England, there are about 700 properties that are vulnerable to being lost by coastal erosion by 2030.

That's only six years away.

If we extend that time period up to 2060, so just another 30 years on, that number increases to 2,000 properties being at risk of being destroyed.

Thanks to coastal erosion.

So for this reason, we need to think of ways of protecting the coast and preventing that loss from happening if we can.

There are many different ways to do this, but deciding the best way to respond to these threats is often a very difficult process.

The main reason it's difficult to decide what to do in these situations is often because of money.

Coastal protection schemes are very expensive.

Most projects actually cost millions and millions of pounds.

As one small example, in Norfolk, a very small town called Sheringham has already spent 7.

9 million pounds on their coastal protection methods between 2003 and 2023, so that's how much they have spent in just 20 years.

Do you know with that amount of money they could have actually bought 10 chocolate bars for every single person living in the UK? That is an awful lot of money.

So what kind of options are we talking about them when we discuss these choices that can be made about coastal protection? There are four main different groups or types of options for coastal protection.

The first are the kind of defences that will protect the current position of the coastline.

We sometimes call these hold the line defences.

The second type of defence is to try and reclaim back some of that land that has been eroded.

We sometimes refer to these as advance the line defences.

So we are building something further towards the sea than the current coastline, and this means we can reclaim the land in between.

A third type of method for coastal protection is to manage the erosion that's taking place in the hopes of slowing it down.

This helps to limit the erosion and can also contribute to flood management.

Of course, the fourth option here, which may not sound like much of an option at all, but is sometimes the best thing to do, is to do nothing.

These are sometimes referred to as no active intervention policies.

And this is where we take action to move the people, move the buildings away from these areas that are retreating because of the dangers that exist there and simply allow nature to take its course and allow erosion to continue to happen.

I'm now going to share with you some of the ways in which those first three options can be carried out.

There are two main types of coastal defence strategies and they're called hard engineering and soft engineering.

When we talk about hard engineering, what we are talking about is putting a barrier between the coastline and the sea.

Hard engineering involves something being constructed, built or made by humans.

These are not natural structures.

They are heavily engineered, very complex constructions, like this wall here in the photo.

I'm going to show you some more examples of types of hard engineering now.

One method of hard engineering is to use cages called gabions.

These big wire cages are filled with chunks of cheap hard rock.

And all of these cheap hard rock chunks are squashed into these cages that are about a metre cubed.

The cages are then stacked on the coast in a row, one on top of the other.

The idea behind gabion is that the waves will crash into the cages and the energy of the wave will be absorbed by those rocks that are trapped inside the cages instead of by the coastline behind them.

This way, the impact of erosion is reduced on those areas of the coastline that are protected by the gabions.

Gabions are usually about a metre cubed in size and they cost around 50 pounds each.

However, the lifespan of gabions can range from just one to maybe 10 years.

This is because they are exposed to a lot of weather conditions, and they easily become rusty.

The wire can bend, it can split.

So generally these would only be a temporary measure to help to hold the line if you like until something more permanent can be put in place.

Another method of hard engineering that's designed specifically to interrupt processes like longshore drift is called groynes.

You might know that longshore drift is the process by which sediments such as sand is moved all the way slowly along a coastline.

Groynes, as you can see in the photograph, are like fences.

They're long fences built at regular intervals along a beach, and this restricts that transportation of sediment because it can no longer freely move all the way along the coastline.

Instead, it is blocked or stopped as it hits one of these fences.

Groynes are usually made of wood.

They can be straight like the ones in the photograph or they can be zigzag shaped.

They can be quite high or they can be quite low.

It all depends on the context of the beach in which they are going to be built.

Groynes cost about 1500 pounds per metre to construct.

So if you add up all of the metres of all of the fences in an area like this photograph of East Eastbourne Beach, it can mount up the cost quite considerably.

That being said, wooden groynes will have a lifespan of 40 to 50 years, so they do last longer than gabion, for example.

One of the first photographs I showed you of hard engineering before was a sea wall.

Sea walls are usually made of reinforced concrete and they are usually built at the bottom of a cliff that is of particularly vulnerable to erosion.

The wall acts as a barrier between the sea and the cliff.

And similar to the gabions, the idea is that the waves crash into the wall and the wall absorbs that energy instead of the energy being directed at the cliff and at the coastline.

There are many different designs of sea walls that we can see in various places around the UK and indeed around the world.

Sea walls can be huge straight concrete walls or they can be curved to match a coastline.

They may have a lip on them or they may be stepped at different levels.

Because of the differences in design, size and structure, the cost of sea walls can vary greatly.

But generally speaking, the cost from around 3,000 to 9,000 pounds per metre.

Now, given that most coastlines are several kilometres long, that several thousand metres long, these can be some of the most expensive coastal defence strategies.

Once they are built though, sea walls will last up to around a hundred years or longer.

I have two more types of hard engineering to share with you.

This next photograph of hard engineering that you can see here is called rip rap.

Rip rap can also be called rock armour.

Now, earlier, we mentioned that the cliffs in Happisburgh, they erode so easily because they are made of soft rock.

Harder rock like granite doesn't erode very easily at all.

It takes a long, long time for granite to erode.

Rip rap consists of boulders of hard rock like granite.

Those boulders are imported from other places that have a surplus supply.

And these huge boulders are then dumped in areas where erosion is a problem.

And they can be used almost to construct what looks like a very natural sea wall.

They look prettier than constructed sea walls, so people often prefer to have rip rap than a large concrete wall.

Boulders like these can cost about 2,000 pounds per metre and will last as long as a sea wall.

If you look at the photograph, you can see that the rocks here, this rip rap, it doesn't look like it's been put there on purpose by humans.

It looks like it could have been there for thousands of years as part of the landscape.

This is why rip rap is often very popular amongst residents of coastal areas.

One final piece of hard engineering to tell you about is something called revetments.

Revetments work in a couple of ways.

A revetment is essentially a wooden fence that is built at an angle against a cliff, so it's sloped, and it runs all the way along a cliff and sticks out to about five metres distance.

The revetment act in a similar way to a sea wall by helping to reduce the wave energy before it can hit the cliff behind it.

But what happens here is that sediment, which is washed up from the sea, is trapped behind that revetment.

That helps to build up behind the revetment, so it's almost creating its own sea wall, which further helps to reduce the energy and it also prevents the buildup of that sediment in other places.

Similar to groynes, because these are made of wood, the lifespan of revetments is approximately 40 to 50 years.

They cost about 2,000 pounds per metre to instal.

You've heard a lot about hard engineering strategies there.

Let's stop here for a quick check on our understanding of those different methods.

This is a multiple choice question.

You can see three photographs which show you different types of hard engineering.

Which one of these shows rip rap? Pause the video and make your choice.

Ready? Okay.

It's picture C.

Those beautiful big boulders of hard rock there are rip rap.

So now that you've seen some hard engineering examples, I'd like to explain some soft engineering examples now.

Soft engineering doesn't involve construction whatsoever.

Soft engineering is actually when we try to work with nature in ways to reduce erosion.

Soft engineering is a lot more low tech than hard engineering is, and it's about trying to manage erosion in a more sustainable way using resources that are already available.

One method of soft engineering is called beach nourishment.

This involves actually replacing the beach material that has been lost to erosion.

What we can do is bring in sand or sediment or shingle from another place that has a surplus of it.

For example, when sand or shingle has built up on a spit, we can take it from that spit and bring it back to the beach that it was eroded from.

Beach nourishment costs about 10 pounds per metre and it can have a lifespan of up to a year, and that's because the processes of erosion continue to happen.

So although we can bring that sand back from the spit where it was deposited and put it on the beach, it will only end up being eroded again and taken back and it will be a continual process.

Another way that we can try soft engineering on beaches is something called beach reprofiling.

When we talk about beach reprofiling, what we're talking about is moving the material, the sand or the shingle that already exists on the beach and moving it around so that we change the shape of the beach.

So for example, diggers can be used like you can see in the photograph to push the sand or shingle a little higher up the beach to form a ridge.

This will help the sediment to be eroded at a slower rate.

Beach reprofiling and other soft engineering methods are often cheaper and much nicer to look at than hard engineering defences such as sea walls.

The cost of reprofiling a beach can vary between 1,000 pounds or up to 20,000 pounds per beach because machinery like diggers need to be hired and paid for.

And again, as the processes of erosion are continually happening, reprofiling of a beach will only last for approximately a year before it will need to be done again.

Let's quickly compare hard engineering with soft engineering.

Hard engineering examples are things like your sea walls, revetments, gabions, whereas soft engineering involves things like beach nourishment or reprofiling.

Hard engineering generally costs more and is not as sustainable as soft engineering methods.

And the other main issue with hard engineering solutions is that they can appear unsightly.

People don't like them.

They can be ugly.

They can spoil people's views because they interrupt the natural systems, they don't work with them.

You've heard a lot now about hard and soft engineering methods of protecting the coast, so let's use our new learning to complete some activities.

First of all, in this check for understanding, I would like you to complete the gaps in these lists of bullet points.

The first column is about soft engineering, and the second is about hard engineering.

Pause the video now while you complete the activity.

Don't forget if you'd like some extra support, you can always work with a geography buddy.

Ready? Great.

Okay.

First of all, we can say that soft engineering is lowering cost and hard engineering is highering cost.

We can say that soft engineering works with natural systems, but hard engineering interrupts them.

Did you identify correctly those missing words? Well done.

Now, bit of a hands-on creative task for you here in Task B.

You have a map here of a two-kilometer stretch of coastline.

This is an area that experiences very rapid coastal erosion, just like Happisburgh, for example.

There are several properties, homes and roads at risk in this area, and the town council needs to decide what to do about protecting the coastline.

As well as having this map here for reference, you are also shown some of the views of the public.

One person is a cafe owner and they are concerned that if the coastal defences are ugly, then tourists would stop coming.

That might have a direct effect on their business.

Another resident is worried about the fact that their home could collapse into the sea.

The town council has a budget of 100,000 pounds to spend on coastal protection.

The council also have a duty to consider the local community and what they think of the new coastal protection methods.

There is a list here of different options that are available, how much they cost, and how long they will last.

Now, either individually or with a small group or even as per work, I would like you to decide which type of sea defence you think the council should choose.

I would like you to explain some advantages and disadvantages of the choice that you make.

Pause the video now while you complete this exciting activity.

Have you finished? There's so many different combinations in different ways, so there isn't really a wrong answer here.

What we are looking for is that you've given thought to having enough money in the budget to carry out the defence that you've chosen and that you understand some of the advantages and disadvantages.

One of the Oak Academy children, Izzy, is happy to share her decision.

She says, "I chose to build a 1000-meter sea wall." She thinks this will be really good at stopping the waves from eroding the land behind it.

And she worked out that it would cost all of the 100,000 pound budget.

Disadvantage, though, is that it would only cover about half of the coastline, which would leave the other half unprotected.

And while the sea wall is strong and will last for a hundred years, it doesn't look very pretty.

So some of the local people will probably be unhappy because their coastline is unprotected and other people will be unhappy because it has made the area less attractive.

So Izzy's choice has gone for something that will be very long lasting and they can afford to do, but the disadvantage is that it isn't gonna protect everyone and not everyone is going to be happy with it.

Well done, Izzy, and well done to you for all your hard work today.

Here's a little summary of everything we've covered in this lesson.

We know that there are many people that live in coastal communities in the UK and that those people are at risk of losing their homes because of coastal erosion, like the people in Happisburgh.

There are a number of different ways that people can try to reduce erosion.

There are lots of hard or soft engineering options such as sea walls, groynes, and beach nourishment.

And whilst all of these coastal defence options do exist, there are many different points of view that we need to consider when we are deciding whether installing coastal defences is cost effective in an area.

Great job today.

I've really enjoyed this lesson and I'm looking forward to seeing you again for the next part of this unit, all about our coastlines.

Bye for now.