Hello geographers, my name's Mrs. Homigo, and I'm looking forward to teaching you today.

I hope you're going to enjoy today's lesson and learn lots.

Let's get started.

Today's lesson looks at a real-life example of a river flooding, and the causes of that flood.

By the end of today's lesson, you'll be able to explain how physical and human factors interacted to cause the River Eden flooding in Cumbria in 2015.

There are three keywords for today's lesson: saturated, flood defences, and floodplain.

Saturated means when the soil or ground has absorbed the maximum amount of water that it can hold.

Flood defences are structures built to protect areas from flooding.

And the floodplain is a flat area of land next to a river that is prone to flooding, and we often find this in the lower course.

There are three parts to today's lesson.

The first is, what happened during the River Eden floods in 2015? The second, how did physical factors affect the flooding? And the third, how did human factors affect the flooding? Let's get started by looking at what happened during the floods.

So the River Eden Valley is located in the northwest of England.

You can see here it's circled on the map.

It's bordered by the Pennines to the east, so an area of high ground to the east, and the Lake District to the west.

The source is on Black Fell Moss and the mouth flows out into the Solway Firth and then on into the Irish Sea.

So the River Eden flows for 145 kilometres northwest, and it flows through a variety of different land uses.

We've got open moorland, particularly up around where the source of the river is, farmland as you move down through the upper and the middle course, and also some urban settlements.

So you've got Kirkby Stephen, Appleby, and Carlisle.

All villages and towns of different sizes that the river passes through between its source and its mouth.

Quick true or false for you now then.

The River Eden does not flow through any urban areas.

Pause the video and come back when you've decided on your answer.

I hope you said false, and you could remember that much of the upper and middle course of the river is in farming and rural areas, but it does flow through urban areas.

For example, Kirkby Stephen, Appleby, and Carlisle, and these are all urban areas.

Let's have a look now then at what happened during these floods in 2015.

So during November, there'd been a lot of very heavy rain in the area, and we can see there if you look at the map, the dark blue area circled, shows that we had very heavy rain, much more than is expected at that time of year in that location.

Because of this heavy rain, the soils across Cumbria had become saturated, which means they were already holding the maximum amount of water that they could.

So if any more rain was to fall on top of them, it wouldn't infiltrate, instead it would run as surface runoff.

The beginning of December, the 3rd-4th of December, saw the weather warnings issued as Storm Desmond started to approach the UK.

The storm hit on the 5th of December, and it had extreme amounts of rainfall.

Over 340 millimetres of rain fell in 24 hours.

This made the river level rise rapidly, and that's because a lot of that rainwater would've flowed straight to surface runoff into the river.

So getting to the river very quickly, causing that rapid rise.

And as a result, the urban areas saw a lot of flooding, in Carlisle and some of the other towns that we looked at.

Following that on the 6th of December, we had widespread flooding in Carlisle.

And we can see in that image there, the streets were covered in water, and homes and businesses were underwater as well.

It damaged over 2000 properties, and roads and bridges became impassable and it needed the support of emergency services.

After that, the 7-10th of December, the flood waters began to recede.

And the damage could be seen, it was widespread, and a cleanup operation had to begin.

Because many homes were damaged, we needed temporary shelters for people to go and stay in.

Mid to late December saw an assessment of the damage that had taken place.

The Environment Agency and the government worked together on this and the government announced emergency funding and support in order to help the area to recover.

And the Environment Agency took a review of the flood defences and the infrastructure that was in place, thinking about how this could be adapted or improved in order to mitigate effects of flooding in the future.

Check for you now.

Can you put these images in the correct order to describe the sequence of events during the River Eden floods? So think carefully at the order of events as to what happened during those floods in 2015.

And pause the video when you've got your answer.

I hope you correctly identified it, as number one being the heavy rain in November that had saturated the ground.

The second one, weather warnings were issued as the Storm Desmond approached.

The third one, talked about the properties that had been damaged in Carlisle and the many roads and bridges that became impassable.

And the fourth, the emergency surfaces helping with the rescue and the cleanup, helping people to cope with the damage that had taken place.

Well done.

Let's have a look now at our first task.

I'd like you to complete these sentences describing the events of the River Eden floods in 2015 in chronological order.

So, in order of time.

It's important to know the specific details because this lesson is looking at a case study of the River Eden floods.

So look back and think carefully about what we've learned as you fill these gaps in.

Pause the video and come back when you've had a go.

Let's see if you've got these gaps right.

Heavy rain during November had saturated the ground in Cumbria.

Weather warnings were put in place.

Storm Desmond arrived on the 5th of December, 2015, and over 340 millimetres of rain fell in 24 hours.

Carlisle and surrounding towns were flooded.

2000 properties were damaged.

The 7-10th of December, the cleanup operation began, temporary shelters were provided.

And late December, a review of the flood management took place.

Well done if you filled out those gaps correctly.

Let's move now to our second learning cycle, how did physical factors affect the flooding.

These are some of the physical factors that affect the flooding and the River Eden.

Drainage density describes the amount of surface streams and rivers that we have.

The more of these, the quicker rain falling in the valley returns to the rivers, and this increases the risk of flooding.

Heavy rainfall before and during the storm event leads to an increase in surface runoff.

Surface runoff means that water reaches rivers much more quickly, and so the risk of flooding increases as well.

And steep relief, we can see there the contour lines very close together.

We have steep relief.

Water is more likely to run down the slopes very quickly and return to the river, increasing the risk of flooding.

If we have a look then at drainage density in this specific example, we know that the River Eden has a high drainage density.

You can see in that image there's a lot of tributaries that join the main river.

So there are many tributaries that transport water from the upland areas into the main river.

So therefore more water is reaching the River Eden more quickly.

And this increases the risk of flooding, particularly in the low lying areas, like Carlisle.

Carlisle is found on the floodplain in the lower course of the river.

So as more water reaches the River Eden and flows downstream, the risk of flooding in Carlisle increases.

The heavy rain from Storm Desmond, if you remember, 340 millimetres in 24 hours, created rapid runoff.

And this was increased because there had been saturated soils because of the heavy rain in November.

And so the river reached record flow levels, so the risk of flooding in Carlisle was huge.

Check for you now.

Which of these are physical factors that contributed to the river flooding in December, 2015? Drainage density, flood warnings, heavy rainfall and steep relief.

Pause the video and make your decision.

I hope you identified it was drainage density.

So the number of surface streams returning water to the main river, heavy rainfall and steep relief.

Flood warnings are a human factor, and we'll come on to look at that later in this lesson.

Let's have a little look then at steep relief in the River Eden Valley.

So we know that the River Eden drainage basin is bordered by the Pennines to the east and the Lake District to the west.

Both of these areas include very steep slopes.

So during Storm Desmond, the steep relief meant that the extreme rainfall quickly became surface runoff.

And as a result, this caused a rapid rise in the river discharge, which increased the likelihood of flooding in Carlisle.

And let's look now at heavy rainfall.

So we know that there had been heavy rainfall throughout November, the soils were saturated, they couldn't absorb any more water.

Storm Desmond brought extreme rainfall, it came with weather warnings.

And in fact, over 340 millimetres fell in 24 hours.

So this extreme rainfall falling on already saturated ground meant that there was a lot of surface runoff, and therefore the river levels rose very quickly, which increased the river discharge and significantly increased the risk of flooding.

True or false then.

Several physical factors combined to cause the River Eden floods in 2015.

Pause the video and make your decision.

I hope you said true, but can you give an example? Have a discussion with a person next to you and see if you can provide an example to support the decision you've made.

You might have said something similar to this.

So Storm Desmond brought exceptionally heavy rainfall, which fell on already saturated ground.

This led to rapid surface runoff down the steep relief of the drainage basin with large volumes of water, reaching the river quickly due to the high drainage density.

So we can see there is the combined effect of all of those physical factors that led to that extreme risk of flooding in the River Eden.

A second task for you now.

Can you explain how physical factors affected the River Eden floods of 2015? And Andeep makes a very good point.

"As this is about the River Eden," which is a located example, "I must remember to include place-specific information in my answer." Pause the video and come back when you had a go at writing your answer.

Your answer might read something like this.

During Storm Desmond, over 340 millimetres of rain fell in 24 hours.

This heavy rainfall rapidly increased river discharge.

The rain fell onto already saturated soils, which meant that very little water could infiltrate, leading to high levels of surface runoff.

The steep relief in the upper parts of the River Eden's drainage basin, particularly in the Pennines, meant that the water flowed quickly downhill into the river.

And this increased the speed at which water entered the channel, raising the River Eden's flood risk.

In addition, the River Eden basin has a relatively high drainage density, meaning there are many small streams and tributaries feeding into the main river.

This allowed water to reach the River Eden more quickly, increasing the volume of water in the channel over a short time.

Well done if your answer was similar to that one.

It's really important to understand how all those physical factors work together to increase the risk of flooding in the River Eden.

Let's move now to look at how human factors affect the flooding in our third learning cycle.

So the land use that we have in the River Eden basin, the upper basin is mainly moorland with areas for grazing sheep.

And on the lowlands they're extensive pastures for grazing and for arable crops.

So we have agriculture.

However, Storm Desmond hit in December.

We know it hit 5th, 6th of December.

Therefore, there was less vegetation cover than in other parts of the year, and fields that would normally be covered with crops were bare.

Now, why is that a problem? Without the vegetation cover and the crops in the fields, there's less interception and infiltration, and so more water returns to the river more quickly as surface runoff.

And this increases the flood risk.

So when the fields and the areas are covered with vegetation and crops, some of that rain will be intercepted by the crops and some will be absorbed by their roots, and so less water runs back into the river.

So the time of year had a big impact because of the way the humans were using the land then.

True or false, then.

Winter meant more vegetation in fields and pastures and on the moorlands of the River Eden drainage basin, which increased infiltration rates.

Decide whether you think that statement is true or false, and why.

Come back when you are ready.

I hope you remembered that was false, and that you said something similar to this in your reason why.

Winter means less vegetation cover because fields are bare of crops and vegetation growth is reduced.

So as a result, infiltration rates are lower and more water is returned to the river more quickly via surface runoff.

This increased the flood risk from Storm Desmond as it took place in December.

Well done.

Let's have a look now at urbanisation.

So urbanisation talks about urban development in the River Eden Valley.

Carlisle, we can see on this aerial photograph, it's a large area in the lower course of the River Eden.

It's built across its floodplain.

Now, urban areas have many impermeable surfaces.

For example, if you think the roads, the pavements, the concrete, the tarmac, and the drainage networks.

These impermeable surfaces all mean that the water cannot infiltrate into the ground.

So it runs as surface runoff back to the river very quickly.

During Storm Desmond, the extreme rainfall meant huge volumes of water were quickly returned to the river in Carlisle by the town's imp permeable surfaces and drainage networks.

And if you look here at this image, the colours show the areas that are at greatest risk of flooding.

The darker the blue, the higher the risk.

So we can see that all along that river, as it flows through Carlisle, there is a risk of flooding, and that's made worse by the fact that Carlisle has increased the number of impermeable surfaces.

Carlisle's flood management in 2015 included, embankments and flood walls.

And we can see there an embankment, which is a raised bank next to the river, and a flood wall, which is a concrete wall built along the river banks.

Both of these types of flood defence aim to increase the capacity of the river channel, which means that it can hold more water than it did initially.

However, if they fail, flood waters can flow out over the flood defences and devastate large areas.

It then becomes very difficult for the water to flow back into the river, which has consequences longer term.

The intensity and the amount of rainfall brought by Storm Desmond, combined with that saturated ground, meant that the River Eden rose much higher than predicted.

So the flood walls and the embankments that had been put in place were not big enough, and the river rose above them.

And we can see here that there is several areas in Carlisle, including West Walls and Willowholme Road, where the flood defences were overtopped and totally flooded areas next to the river.

Check for you now.

Which of these are human factors that affected the river flooding in Carlisle in 2015? A, urbanisation, B, failed flood defences.

C, steep relief, and D, arable farming.

Pause the video and make your decisions.

Hopefully you said urbanisation, and failed flood defences.

Let's look now at our final task.

We've got a table here.

On the left-hand side, you've got the summary of the physical factors that contributed to the flooding in the River Eden.

Saturated ground from heavy rainfall throughout November, intense rain during Storm Desmond, over 340 millimetres in 24 hours, steep relief in the upper course of the river, and high drainage density in the Eden Valley.

Can you complete the other side of the table, and describe three human factors that contributed to the river flooding in Carlisle in 2015? And for question number two, using this table to help you, can you explain how human and physical factors interacted to cause the severe flooding in Carlisle in 2015? Pause the video and come back when you've had a go.

Your table might have looked something like this.

Urbanisation, large areas of impermeable surfaces in Carlisle and other urban areas.

Arable fields were bare as it was winter, reducing infiltration rates, and existing flood defences failed in places, for example, West Walls and Willowholme Road, causing extensive flooding with flood waters then trapped behind the remains of embankments.

And your second question, explain how the factors interacted, might look something like this.

A key physical factor was the extreme rainfall.

Over 340 millimetres fell in just 24 hours due to Storm Desmond bringing moist air from the Atlantic.

The ground was already saturated from previous rainfall, leading to significant surface runoff, which was then delivered rapidly to Carlisle by the River Eden's high-drainage density and steep relief of the drainage basin.

Human factors made this worse.

Impermeable urban surfaces increased surface runoff into drains and rivers.

And the flood defences in Carlisle were also not high enough and were overtopped, allowing floodwater to enter the city, which then became trapped behind the flood defences.

Well done if you managed to consider how human and physical factors interacted to cause the severe flooding.

Let's look now at a summary of today's lesson.

So Storm Desmond brought heavy rain in December, 2015, causing the River Eden to flood.

Physical factors, including the already saturated soil and steep slopes in the upper basin caused fast surface runoff.

Human factors included urban development, Carlisle has lots of impermeable surfaces, reducing infiltration, and increasing surface runoff.

And the combined effect of human and physical factors increased the risk and impact of this flood.

Well done.

I hope you feel that you can now confidently discuss how human and physical factors together caused this river flooding in the River Eden in Cumbria.

I look forward to seeing you all again soon.