Lesson video

Hello, and welcome to today's geography lesson with me, Ms. Roberts.

This is a lesson from our unit about our coasts and what shapes life at the coast.

In today's lesson, we are going to be thinking about how we protect our coastline here in the UK.

By the end of the lesson today, you are going to be able to describe how different methods of hard or soft engineering can protect the UK coastline from erosion.

In order to do this, we are going to need to use some really good geographical terminology.

So let's begin by going through our keywords.

I'd like you to be able to use these keywords when you are talking about how we protect our coastlines.

The first keyword is erosion.

Erosion is a natural process, and in that process, the earth's surface, whatever that surface may be made from, whether it is rock, or soil, or sand, that surface is worn away, and when it is worn away, it is then transported from its original location to somewhere else.

The next important word for today is a cliff.

We often see cliffs on coastlines, don't we? They are very tall, vertical rock faces.

The next keyword is wave.

A wave is the movement of energy across water, and we can see this by the white water and the height of a wave as it moves across.

Our final key word for today is beach.

It's one of my favourite places to be is the beach.

The beach is that strip of land at the coast, which we find between the low tide mark and the storm tide mark, and beaches can be made up of materials or sediment like sand, mud, or stones that we sometimes refer to as shingle.

There are two parts to today's lesson, and I'm going to spend half of the lesson talking to you about hard engineering and then the rest of the lesson talking to you about soft engineering.

So let's begin by finding out what exactly is hard engineering.

The coastline of the UK looks the way it does and is shaped the way it is shaped, because of natural processes called erosion, transportation and deposition.

The methods of hard engineering and soft engineering that we are looking at today help to reduce these natural processes.

In particular, the process of erosion.

In the UK, in England, on the east coast, some very severe and high rates of coastal erosion are experienced every year.

We can see how extreme erosion is in these places by comparing old and new maps.

This part of England is called the Holderness Coast, and this area of Mappleton is experiencing erosion of around two metres a year.

You can see by comparing these maps just how much closer this settlement now is to the edge of the cliff.

As villages and settlements like Mappleton become ever closer and closer to the sea, the risks become greater and eventually homes, buildings, roads, vehicles could all be lost if they fall into the sea.

To reduce erosion and lower these risks, there are protection methods that we can use along our coastlines.

We can use hard engineering and soft engineering.

I'm going to take you through some specific methods of hard engineering in just a moment, but before we do that, let's have a quick check on our learning so far.

Multiple choice question for you here.

Why do some coastlines need hard engineering or soft engineering? Why do we need it? Is it A, to stop humans destroying beaches? B, to protect endangered species, or C, to reduce the erosion of coasts? Have a think and make your choice now.

Ready? The answer is C, to reduce the erosion of coasts.

That's what these protection methods are for.

Many methods of hard engineering are designed to reduce erosion by absorbing energy from waves, by slowing down those waves that hit the coast and by doing so will reduce erosion.

Hard engineering involves some construction, some building of fixed structures that we can see at the coast, and those fixed structures will help to reduce erosion or flooding or both in that location.

Some examples of hard engineering that we are going to look at some more now are called groynes, sea walls, and gabions.

This is a closeup picture of a gabion.

If we zoom out, you would see that this is a wire cage of hard rock.

We'll see some more about gabions later.

Thinking about those three images that you can see there, which one of these three pictures that are now muddled up in a different order? Which of these shows groynes? Make your choice now.

Ready? Is it A? No, A is a sea wall.

It's not C, because C is a closeup of a gabion.

The correct answer here is B.

B shows groynes at the beach and groynes are the first method of hard engineering that we are going to explore.

This picture shows a groyne on a beach.

You can see that long fence-like structure that is sticking out from the beach into the sea.

A groynes is a fence-like framework built at a right angle to the beach and they are usually made of wood or concrete.

They might also be made from piles of very large boulders.

They're called rock groynes.

Groynes are designed to reduce erosion because they trap or hold sand on the beach in between them, so these groynes are built in a long row at regular intervals along a stretch of beach and sand is held in between each pair of groynes so it isn't eroded away as it might naturally be if the groynes were not there.

We can understand how groynes work and how they do this if we think of them as part of a process.

The groynes are trapping sand between them.

Because they are trapping sand and that sand is not being eroded or taken away anywhere else, the beach can then become naturally wider.

A wider beach with more sand is stronger, so more of the wave energy can be absorbed by the beach and therefore the erosion is reduced.

Let's move on now and look at another method.

Let's think about gabions.

Here is this closeup picture of a gabion.

A gabion is a wire cage about a metre cube and it's full of chunks of hard rock like you can see here.

We take these cages and we place them at the bottom of a cliff or another part of exposed coastline that we want to protect.

Because they're only about a metre, we have to place lots of these, side by side in a very long row or stack them up to make one bigger, stronger structure.

What then happens is at high tide, the waves come and they crash into the gabion instead of into the cliff behind them.

When that happens, the energy from the waves is absorbed by the gabion instead of the cliff entirely taking all of that energy.

This reduces the erosion that's taking place there and the cliff is protected.

The next method of hard engineering works in exactly the same way.

Think about a wall, this is a sea wall.

They're made of reinforced concrete usually and they are built or constructed in front of a cliff or another part of the coastline that we want to protect.

Some walls can be very large, very tall.

Some can be much smaller.

They can be various shapes and sizes.

A lot of sea walls are curved, but many are also straight.

Some are even built in various types of architectural shapes to make them more of a tourist attraction.

Sea walls, like gabions, act as a barrier, so they protect the cliff or the coastline behind them.

The waves come along and they crash into the wall.

The wall absorbs that energy from that crashing wave.

The cliff behind the wall is then protected and as a result erosion is reduced.

So, seawalls there and gabions are both doing a very similar job to absorb the wave energy.

Let's try a quick question about hard engineering.

We've seen three methods, seawalls, groynes, and gabions.

Which of those three methods is the one that involves using cages of hard rock? Have you decided? The answer is C, gabions.

Well done.

Now, I'd like to take what you know so far hard engineering and protecting the coast and put it to use by completing this short activity.

Here you can see the pictures of the hard engineering methods we've been looking at.

I would like you to write a short description of each method.

I would like you to describe what it does to combat coastal erosion.

Pause the activity now and then when you are ready, come back, and I'll share some example answers from the Oak Academy students with you.

Ready? Okay, let's have a look then.

You may have had some very similar ideas to these examples.

Groynes.

Wood or concrete fences built at right angles to the beach.

They trap sand or shingle so it is not eroded away, and so they maintain the beach by making it wider.

Sea walls.

Reinforced concrete walls are built in front of cliffs or coastlines to protect them from erosion.

They block strong powerful waves and absorb energy.

When the waves crash into the sea wall.

Gabions.

Wire cages full of hard rock that are placed at the base of cliffs.

Waves crash into them and they absorb the energy from the wave.

This protects the cliff behind the gabion from erosion.

All three short, succinct, and accurate answers.

It's great to see a lot of geographical terminology being used there as well.

Now we're going to explore soft engineering methods and see how these are different to hard engineering methods that we use to protect the coast.

The main difference between hard and soft engineering is that soft engineering involves working with nature to reduce erosion and flooding at the coast.

The examples of soft engineering that I'm going to explore with you in some more detail are called beach replenishment.

We sometimes call this beach nourishment as well.

And then dune stabilisation.

Sometimes this is called dune regeneration.

Although there are other methods of soft engineering, these are the two we will be exploring today.

Many methods of soft engineering are aimed at reducing or even trying to stop the natural processes of erosion, transportation, and deposition that are happening at the coast.

There is some soft engineering happening in this photograph that you can see here.

Soft engineering can also involve human interaction with natural processes and purposeful reshaping of coastal landscapes.

Before we move on to look at those two methods in particular, let's just stop at this point and think about what we know so far about soft engineering.

Listen to this sentence, soft engineering involves building structures at the coast.

Would you say that that sentence is true or false? Have you decided? This sentence is false.

Now, can you give me a reason why it is false? Ready? Perhaps you have ideas like these.

Hard engineering is building structures at the coast.

Soft engineering is when we work with nature at the coast.

Those structures that we build are part of hard engineering.

Sea walls, gabions, groynes, they're not part of soft engineering.

Let's now look at beach replenishment.

This photograph shows beach replenishment happening.

Beach replenishment is when we deliberately replace beach material such as sand or shingle or whatever other the sediment a beach is made from.

We replace that material that has already been lost due to erosion.

Sand or shingle is brought from somewhere else where there is an excess of it.

Often sand for beaches can be found on sandbars offshore, so not on the coast.

We don't need the sand in those sandbars, but we do need the sand on our coasts, on our beaches so we can excavate that sand from the sandbar and bring it and replenish our beaches with it.

The process of beach replenishment helps us to maintain our beaches, but we have to keep doing this.

It needs to be redone very frequently because we are not stopping erosion in this case.

The erosion will still continue.

The material that we replenish the beach with will be eroded away, but then we take it back from the offshore sandbar and we replenish the beach.

We can think of how this works as a process.

The destructive waves come along and they remove that beach material.

The beach becomes thinner and thinner as more and more waves erode it and destroy the beach.

Humans come along and we replenish that beach material.

We dump a load more sand or shingle or whatever the beach is made from onto the beach.

That's what was happening in that photograph.

This process can then repeat and continue.

Erosion can happen again, we replace the material again, and ultimately as this cycle goes on and on, it means that that beach is not destroyed.

Isn't that an interesting concept? Let's have a look at what we know about beach replenishment now with this quick check.

Here are four sentences.

I would like you to tick the column to decide whether each sentence is true or false.

Ready? Let's check.

Beach replenishment is only used on sandy beaches.

That is false.

It can be used no matter what type of sediment the beach is made from.

Beach replenishment works with nature to reduce coastal erosion.

That's true.

Beach replenishment prevents the destruction of beaches by waves.

Absolutely, that's what it's designed to do.

Beach replenishment needs repeating regularly to be effective.

This is also true because erosion continues.

The next method of soft engineering that we are investigating today is called dune stabilisation.

You can see some sand dunes in this picture.

Sand dunes are little hills, sometimes quite big hills actually, or mounds of sand, and these form naturally alongside beaches.

They are a natural defence against flooding and erosion.

They protect the coastal community behind them and they can prevent beaches from eroding.

Look at the picture and you can see some grass growing from this sun dune.

This is a special type of grass that grows along the coast called Marram grass.

This grass, which is naturally there, helps to strengthen dunes so that they can grow.

Whilst Marram grass grows naturally, humans can help by planting more grasses on the dunes.

This helps to make them even stronger so they can go bigger, and this helps dunes to be maintained and stabilised.

Sand from the beaches that may otherwise be eroded by wind is trapped in the grasses instead of being eroded, and therefore with the buildup of this sand, the dunes can grow.

The stronger the dune, the better it is at reducing erosion and protecting the coast.

The dunes in this picture are at a place called Formby in Merseyside, and these dunes protect a very long stretch of coastline there in the northwest of England.

So this time I have sentences about dune stabilisation.

I'd like you to tick the column to show whether these sentences are true or false.

Ready? Okay.

Dune stabilisation involves planting grasses on mounds of sand called dunes.

Absolutely, that's true.

That's exactly what this process does.

Dune stabilisation helps to reduce erosion of beaches.

That's true because the sand is trapped in the dunes.

It doesn't leave the beach.

Dune stabilisation involves building a wall to stabilise the sand dunes.

That's not right, is it? That's false.

Hard engineering is about building walls.

Dune stabilisation is a type of soft engineering.

Finally, dune stabilisation helps to stabilise an existing natural feature of the coast.

That's right, sand dunes are a natural defence for our coastlines.

So let's put all of our new learning from this lesson to use in one final activity.

I want you to select a method of hard engineering and a method of soft engineering of your choice from those that we have looked at in this lesson.

I want you to compare and contrast them.

What are their similarities and what are their differences? Pause the video and when you come back, I'll share some ideas with you.

Ready? Good.

Your answer may look like this.

I have chosen to compare sea walls and beach replenishments.

Both of these methods help to protect the coast by reducing erosion.

So there's our similarity.

Sea walls are constructed from strong concrete in front of a cliff.

The waves crash onto the sea wall and the cliff is protected, so erosion is reduced.

Beach replenishment is when sand or shingle is added to a beach to replace what has already been eroded away by destructive waves.

This has to be repeated in the future to maintain the beach.

So those descriptions are how they are different.

Did you choose those methods or did you choose others? I'm sure you will have had similar ideas to these.

We've discovered a lot today about how we protect our coastlines, so let's review our learning.

We now know that hard engineering is the building of fixed structures, and these are designed to slow down the waves at the coast and the rate of erosion.

Soft engineering is when we work with nature to reduce the risk of flooding and erosion at the coast.

Some examples of hard engineering include groynes, sea walls, and gabions.

Some examples of soft engineering include beach replenishment and dune stabilisation.

I hope you have enjoyed investigating the methods that we use to protect our coastline, and I'm looking forward to joining you for another lesson from this unit about what shapes life at the coast.

See you next time.