Lesson video

Hello there.

Welcome to today's geography lesson.

I'm Ms. Roberts and this is a lesson from our unit, "All About Coasts".

We are investigating what shapes life at the coast.

Now this lesson is about using GIS to visualise and analyse coastal erosion.

By the end of the lesson today, you will be able to visualise and analyse coastal erosion using GIS platform.

Don't worry if you're not too sure what GIS is now.

I'm going to take you through everything step by step, beginning with some key terminology that we want to be able to use and understand in this lesson.

The first you've heard several times today is an abbreviation, GIS.

This stands for Geographic Information System.

A GIS, a geographical information system is a computer mapping system and it's a system that can capture and display or show us geographic data.

And this can be used so that we better understand spatial patterns in the world around us.

We can see things on a much bigger scale if we use a GIS.

We are learning today how to use that GIS to visualise and analyse coastal erosion.

But what does that mean? Well, visualising is when we are able to create images of things in our minds and this helps make things easier for us to understand and get to grips with.

Analysing is where we look at something and we really break it down, we look for patterns and relationships between things and find out what connections we can make.

So today we are using that geographic information system to create images of things in our mind and to identify patterns.

And this all relates to the erosion of our coastlines.

There are two learning cycles in this lesson.

In the first half of the lesson, we're going to think how can we use GIS to measure coastal erosion.

And then later we are going to think about how can we use GIS to analyse coastal erosion.

Okay, so let's get started first.

So often geographers can use photographs.

We can use photographs to help us visualise the impact of coastal erosion on people or the environment, for example.

Looking at the photograph here, we can clearly see that there is a clifftop that's been eroded away.

It looks very much like it's still in the process of eroding to me and there is a construction of some sort, a building there, which is something used by humans.

It could be part of somebody's garden shed or a caravan.

And this is perilously close, I would suggest to the top of that cliff.

If erosion continues, it's highly likely that that structure will be lost to the sea.

That's a lot of information from a photograph.

But are photographs limited in what they can tell us? What might those limitations? Photographs do give us lots of useful evidence.

They show us that coastal erosion is happening and they can give us clues as to why it's happening.

But there are things they don't tell us.

They don't tell us how quickly that cliff has eroded there, how quickly is it still eroding.

They don't give us any information about any erosion that's happening beyond the camera's field of view, that means what's happening to the left, to the right and beyond the area we can see in this photograph.

Photographs also can't tell us any causes of erosion beyond the camera's field of view.

So we can only make suggestions based on what we can see in that one small photograph.

So thinking about photographs, is this true or false? What would you think? Photographs cannot give us any useful information about coastal erosion.

Hmm, is that true or is that false? Have you decided? I think that that statement is false.

Now can you give me some reasons why we can say that that statement is false? Here's some ideas.

Perhaps you have some ideas like this as well.

Photographs are useful sources of evidence about coastal erosion and they can give us lots of clues about the causes of erosion, the impact of erosion, where it's happening and what's going on.

But they are limited.

We can only see one small area in a photograph.

We know nothing about what's going on beyond that field of view.

So because of that limitation there is a lot that we just can't tell from a photograph.

If we use a GIS, however, instead of a photograph, we can visualise erosion and we can measure the scale and the speed of it.

Now the screenshot image that you can see here is from a GIS that you can access and use and you are going to try access and using yourself in a moment.

But first we are going to look at a video and Mr. Schofield is going to tell you some more about how to use this GIS.

<v Mr. Schofield>In this video,</v> we're going to be using the National Library of Scotland's side by side map viewer to investigate, visualise and measure coastal erosion.

Now this GIS system is really useful for geographers because it allows us to compare maps and satellite imagery side by side.

So we can see on the left hand side of this screen, we've got a map and we can see in this menu box that it's says select map and it says, "OS Six Inch 1888-1915".

If I click on this, I can change this map into lots of different maps.

We're actually gonna stay on this map and on the right hand side, we've got a present day ESRI world imagery.

So that's satellite imagery from the present day.

So what we're able to compare here is an old map on the left with new satellite imagery on the right.

So what we're going to start with is we've got to find a place where we can investigate coastal erosion.

So I'm going to come to this top left hand corner and you can see the mouse cursor coming across to the left and I'm going to click on the search, the magnifying glass and I'm going to type into here Skipsea.

Oops, I spelled it wrong.

Let's try again.

It's Skipsea.

And it says there "East Riding of Yorkshire, Yorkshire and the Humber." And that's correct.

Now if I zoom out for a second and I'm just using the scroll wheel of the mouse, I could come to the top left hand corner and press this zoom out button here.

We can see that this is on the east of England.

It's along what we call the Holderness coast.

And so we see we've got something called Flamborough Head up here.

It goes down to something called Spurn Point, and Hull, major city is just down here.

So we're going to investigate this part of the world.

This is Skipsea.

I'm going to zoom back in and you should take us straight back to Skipsea.

There we go.

So this is Skipsea here.

Now if I zoom in, what we can do is we can actually look at coastal erosion visually.

So if you notice where my mouse cursor is, the little arrow on the left, where I move it around this map, there's also a little cross that moves around the map, the satellite imagery on the right.

If I go to this corner, the sharp corner on the road, you'll notice it's also the sharp corner on the satellite imagery on the right, which suggests that this road was here back when this map was produced between 1888 and 1915.

And it's still there now.

Now they're in the same point which basically means that they are what we call geo-referenced and that means it's using the exact coordinates to work out that they're the same location on both of these, on the map on the left and the imagery on the right.

So if I come to the coastline, what I can do is I can put my mouse on here and you'll notice that where my mouse cursor is on the left, on the left hand map, it's still quite a long way from the sea.

You can see there's a road here, there's car parking.

But the cross on the right is right on the beach.

And what this is suggesting is, well it's not suggesting, it's telling us that coastal erosion has meant that this land has been eroded, this section here in between the periods of these two different maps.

What I can do is I can go to the top and click on Swipe.

I can actually go into this middle point here and drag this handle over and look at the land that's been lost.

So this land here that I'm dragging across has now become sea, but back when that map was produced that bit was land.

And that's an incredible visual reference of coastal erosion.

But we can be more accurate than that and we can be more accurate than that by using the measuring tool.

So what I'm going to do is I'm gonna come up to the right hand corner and we can see there's a little tool there saying, "Measure Tools." I'm going to click on that measure tool.

I'm going to go down to the bottom one where it says measure distance and I'm going to click on it.

And what I can do is I can go and look, I'm using the satellite imagery on the right here.

You'll see the mouse cursor with a little orange circle on it.

I'm going to click on where the edge of the coastline is.

I'm just gonna come to about here, which is on this sort of cliff line and I'm going to take it, I'm gonna come out into the sea up until the point where if we look on the map on the left you can see the cross on the left to where the old coastline used to be where the old cliff line, you can see there's sort of arrows pointing with the black line there and I'm going to click somewhere on this.

So I'm going to double click and it gives me a distance and you can see there it says 118 metres and that is the distance that has been lost, the coast, the amount of land that's been lost between the map on the left when that was produced and the satellite imagery when that image was taken, which is around the present day.

<v ->Thanks, Mr. Schofield.

</v> That was really interesting.

I thought it was so informative being able to swipe that map across and just see the extent of land that had been eroded there in that area.

Were you paying attention then to Mr. Schofield's video? I'd like you to just have a go at this multiple choice question.

Can you complete the sentence? The ESRI world imagery on the right is.

Older than the map on the left, from the same year as the map on the left, or more up to date than the map on the left? Make your choice now.

Have you chosen? The ESRI world image on the right is more up to date than the map on the left.

The right hand side shows the most recent images of the area and the map on the left is from a point in history.

So we can use a GIS like this one and we can take information from that GIS and use it to work out other things.

What we can do is work out the average coastal erosion rate per year using the information from the GIS.

We know that we can find the distance that's been eroded.

Mr. Schofield just showed us how to do that.

And we know the years that are between when that map was produced and the most recent images that we can see in the GIS.

If we divide the distance by the time, then we will find the average erosion rate per year.

So in this case we found that the distance eroded, we've rounded here to 118.

The years between the maps was 110 and that means the average erosion rate per year is 1.

07 metres.

Now that might seem like not very much, but when you consider that that's 1.

07 metres of the entire length of the coastline, you start to realise just how much that actually is in reality.

And that 1.

07 metres of the entire stretch of coastline is happening every single year, which ultimately leads to these big swathes of land being eroded at the coast.

So let's try a bit of a calculation ourselves.

Let's take a hypothetical situation.

If we've got 200 metres of land that's been eroded and it's taken a 100 years for that erosion to happen, what would the average rate of erosion per year be? Now you can pause the video while you do the calculation and then when you come back, I'll share the answer with you.

Okay, right here we are.

So the distance is 200 metres, the years, the time is a 100 years and that gives us 200 divided by 100 is two metres per year in that situation.

Good job.

Right, your turn now.

We are going to use a GIS to do some tasks yourself.

You're going to use the same GIS that you've just seen in the video.

If you follow the link here, you will get straight to the webpage that you need.

First of all, I want you to get used to using the GIS system by completing these tasks to look at the rate of coastal erosion near Atwick, which is on that same area of the Holderness coast that we were looking at in the video.

There are step-by-step instructions here for you to follow.

You are going to use the search tool to zoom in and actually locate Atwick.

You are going to use the measure distance tool.

You are going to compare the old and the new maps and then write down the distance that's being eroded.

And like we did before, you can round to the nearest metre.

After you have done that, I want you to use the information you have found to work out the average rate of erosion and we have given you the formula here.

Pause the video now, take your time to get used to using the app.

You may want to do things a couple of times until you get used to all those features.

And when you've completed all parts of task A, come back and I will share the answers with you.

All done? Great.

Now that may have been your first attempt at using a GIS system, so I hope you have found it to be a very useful tool that you'll be able to use now and in the future.

So here's a screenshot from the GIS.

You may have had this yourself and I've circled the cross on the left hand map because it wasn't perfectly visual on the photograph.

So the distance that has been eroded as we can see is approximately 100 metres.

It was around about a 100.

01 metres exactly, but we're going to round for ease of our calculation today.

Now we can work out the average rate of coastal erosion in Atwick.

We have a 100 metres that's been eroded.

There is 110 years between the maps.

A 100 divided by 110 gives us no 0.

9.

If we think nor 0.

9 of a metre, it's probably easier to use centimetres.

So we can convert that to 90 centimetres as the average rate of coastal erosion per year in Atwick.

Great job.

That brings us to the second part of our lesson and in this part of the lesson we're moving on from thinking about measuring coastal erosion to analysing coastal erosion.

Remember to analyse is to really break something down and to look for those patterns and connections.

Let's look at a very basic example of analysing something and making connections just to make sure that we all really understand what we are trying to achieve here.

Let's look at some maps.

On the left we have a topographic map showing us the relief of the United Kingdom and then on the right hand side we can see a map that shows us average rainfall for January in the United Kingdom.

So on the relief map, the key there shows us the green areas are the flattest areas of the UK.

Very little height above sea level there, moving up to about a thousand metres above sea level in the darkest orangey yellow sections.

The rainfall map, the palest grey blue colour, very little rain received in January.

And those areas through to the darkest blue colours are the areas where the most rain is received.

Look at those two maps side by side.

What do you start to notice? I've noticed that the darkest areas on the map on the left tally up with the darkest areas on the map on the right.

So this to me means that there's a connection there.

The connection is that areas that are high altitude are also areas that experience heavy rainfall and that means that the inverse is true as well.

Those areas that are not very high, the green areas on the relief map, they tally up with the pale areas on the rainfall map.

So that means that areas of low altitude are also areas of low rainfall.

I can also make connections about where places are located.

I can see from the rainfall map that the west is wetter and the east is drier.

We can literally draw a line down the country, which you can see I've done here.

Before we move on to look some more at analysing using a GIS, let's have a quick think about where we are at the moment.

True or false? To analyse means to give details or characteristics of something.

Is that true or is that false? Have a think and make your choice.

That's not quite true.

That's not really what analysing is.

Why not? What reasons can you think of? Perhaps you thought of some reasons like this.

Describing.

I've used the word there, haven't I? Talking about the characteristics of something is describing it.

That's not the same as analysing.

Analysing and describing are two different things.

Analysing is really breaking something down, looking at something in depth and identifying patterns, relationships and connections.

Well done.

So we're gonna think now about coastal erosion.

We are analysing coastal erosion and we want to think about the ways in which coastal erosion is being managed on our coastlines.

We can look at the rates of coastal erosion to analyse whether or not any of that coastal management is actually working or not.

So for example, there is a place called Mappleton on the Holderness coast.

We have identified that location here on the maps and at Mappleton, a rock groin has been built.

We're going to analyse the usefulness of that rock groin using a GIS.

We're going to use the same GIS as before and Mr. Schofield is going to join us again to share some more information about how to use this GIS for analysing.

<v Mr. Schofield>In this video,</v> I'm going to be using ESRI's Wayback app to analyse coastal erosion.

So this is the ESRI Wayback app.

And what the Wayback app does, is it shows different satellite imagery over the last decade.

So you can see on the left hand side, we have a toolbar menu here and you can see that we've got these different dates starting at the bottom from 2014 and it goes all the way up to 2024.

And what this means is that we have satellite imagery for these different dates and you can see as I kind of move my mouse up the screen, it changes that little window in the middle of the screen there.

So what we're going to do is we are going back to the Holderness coast.

So I'm going to type in Mappleton and you can see here we're in Mappleton.

That's on the Holderness coast from the east of England.

If I zoom right out, I'm using the scroll wheel of my mouse, so you can see where that is in the UK.

So it's here, sort of northeast of Hull, it's on the Holderness coast.

I'm gonna come back in, you can see maps in there.

And what we're going to do is we're going to be analysing the impact of these rock armour groins.

So these are groins which are designed to prevent longshore drift and that captures sand.

And we're going to analyse the impact of this.

So we can see we've got a rock armour groin here, got a rock armour groin there and we've actually got something up here as well.

So that is the rock armour groins on the beach in Mappleton.

We don't have rock armour groins further south.

So what we can do here is we can look at how this area has changed from 2014 through to 2024 and there's different ways we can do this.

So if I click on this play button on the left hand side and click on that, what it will do is it will change the images from 2014 and it will go through each of the images to see how this area is changed.

So that's one handy tool.

And what we're going to use is we're going to use this Swipe tool.

So on the left side it says, "Toggle Swipe Mode".

And there we've got the screen that's now split and what I can do is I can take the oldest date, we can have that on the left, that's now 2014, and on the right hand side I'm going to click the top date, which is 2024.

So that's the most recent satellite imagery I've got.

Now what I can do is I can take these drag handles in the middle, it says, "Drag to compare," and I can look at this area to see if there's been any changes.

I want to zoom in slightly.

There we go.

And that will work.

So on the left we've got what it was like in 2014 and what we can see here is we've got this road to the beach, we've got these big rock armour groins, got this cliff and we've got this car park here.

So let's see how it's changed.

So I drag the handles, I'm taking this to the 2024, which is more like the present day.

We can still see the rock armour groins, but as we keep dragging we can see that the cliff has eroded westwards and the car park has become much, much smaller.

These cars are very, very close to the edge of the cliff now.

So come back again.

And it comes back again.

Now by using this app, we can analyse the impact of this rock armour groin.

Let's look going north of these groins here between these groins coming this way.

If we swipe, we can see that actually there isn't a big difference in the location of the cliff here.

So not a big difference.

So this area here doesn't seem to change a great deal.

You can see slight changes in the images, but actually in terms of the erosion, the cliff has stayed in a similar position.

If we move south and we swipe across, we can see that the cliff has eroded backwards and this car park has eroded.

Now what that allows us to do is to work out the relationship between putting these rock armour groins in and erosion.

And we can think of it to the north of this big rock armour groin and the south.

And we can see to the north, these rock armour groins seem to be working.

They to be keeping sand on the beach, which will absorb wave energy and will reduce erosion.

To the south where there aren't any rock armour groins, we can see that well there is significant amounts of erosion and the car park has eroded.

So you can see how we can use GIS in order to analyse coastal erosion along the coastline.

<v ->Thanks, Mr. Schofield.

</v> Wow, what a difference it made where those groins were.

I can't believe how much the cliff had retreated and that car park was just shrinking.

So were you listening carefully to Mr. Schofield? Then let's have a couple of questions to check.

Here's an image of one of the tools from the ESRI app.

What is the function of that tool? This is the Swipe tool.

This is what we use to drag between images to compare points in the past with more recent images.

True or false? Coastal erosion is likely to be the same in different places along a stretch of coastline.

Is that true or is that false based on what you've just seen? This is false, isn't it? So based on that video on what's happening in Mappleton with the rock groins, can you give us some reasons why? You might have had some ideas similar to these.

I will use Mappleton as a reference.

Coastal erosion does vary between different places on one stretch of coastline, and that's because it's influenced by many different factors.

There are human factors such as whether or not coastal defences have been built at all and physical factors such as the rock type.

We can evidence this because of what's happened at Mappleton where the rock groins have been constructed and we said north of those rock groins erosion had been stabilised.

They were managing to keep sand on the beach and the wave energy was being absorbed.

But south of the rock groins being built, erosion was still happening at quite a significant rate.

The cliff was retreating and human features like that carpark we saw was becoming smaller.

So task B now is an opportunity for you to have another try at using the GIS for yourself.

You can click on the link and again, it will take you exactly where you need to go.

There are several tasks again here for you.

First of all, you are going to be analysing the impact of coastal defences that have been built at Hornsea as opposed to the absence of coastal defences at another location, also on the Holderness coast called Great Cowden.

There are step-by-step instructions there to follow them through one by one from using the search tool first to locate Hornsea.

Zoom in, have a good look there, identify the coastal defences, what are they, what coastal management is being used.

Follow the instructions to use the Swipe tool to switch between some imagery from the past and some more recent imagery to see what's been happening in the area.

And look very carefully and think to yourself, has that area been eroded? What is happening there? When you've done that, repeat the same thing for the area of Great Cowden.

You can either type that into the search tool or if you go back to Mappleton and just scroll south, you will find Great Cowden there.

Again, zoom in, have a look at the area and you'll notice here, there are no coastal defences.

Use the Swipe tool again and compare imagery from the past with the imagery from more modern times.

And then I would like you to think about what that research, what does that GIS tell you about the impact of sea defences on coastal erosion.

Pause the video now while you complete the task.

You could work with a partner if you wish, and maybe share your ideas.

When you come back, I will share some example answers with you.

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

First of all, let's think about what's been happening in Hornsea.

I have got a screenshot here of the area from the app and I was asked to identify the defences that were there.

And what I can see are groins.

The satellite imagery here shows that groins have been built on the coast.

There is also rock armour and a sea wall there.

There has not been significant erosion in this place.

I've found that by comparing the images, there's not a lot of erosion happening there where those defences have been built.

In Great Cowden, we can see that there are no coastal defences there and we can see that there has been significant erosion.

So this tells us the connection.

The relationship we are seeing here is that when there is coastal management and defences are built, then there is less erosion, whereas places without coastal protection do experience significant erosion.

And there you go.

This brings us to the end of our lesson where we've realised that we can use very modern technology like a GIS to help us not only to visualise, but to analyse and interpret what's happening along our coastlines.

I hope you have enjoyed the lesson as well today and will join me again for the next lesson to find out more about what shapes life at the coast.

Bye for now.