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Hello, geographers.

My name's Mrs. Hormigo.

I'm really looking forward to teaching you today.

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

Let's get started.

Today's lesson looks at the costs and benefits of managing flood risk.

By the end of the lesson, you'll be able to assess the costs and benefits associated with hard and soft engineering strategies, which are aimed at reducing river flooding.

There are three key words for today's lesson, sustainable, hard engineering, and soft engineering.

Sustainable is meeting the needs of the present without compromising the ability of future generations to meet their own needs.

Hard engineering is the use of artificial structures and technologies to control natural processes such as flooding or river erosion.

And soft engineering uses natural processes and landscape features to reduce the risk of flooding and erosion.

There are two learning cycles for today's lesson.

The first, the cost and benefits of hard engineering, and the second, the cost and benefits of soft engineering.

So let's get started and have a look at hard engineering strategies.

Firstly, let's think though why do we manage rivers? To reduce the risk of flooding, to reduce erosion, to protect property and infrastructure, to support sustainable development, to allow safe land use, and to improve water quality and wildlife habitats.

And in order to do all of these things, we use hard and soft engineering.

River management tries to reduce the risk and increase the benefit that rivers bring to people, the economy and the environment.

So hard engineering is the use of manmade artificial structures to control natural river processes, such as river flooding and erosion.

The methods are usually expensive but highly effective in the short term, but they may also have a high environmental impact.

Some examples include a flood relief channel, embankments, flood walls, and flood barriers.

And we're gonna have a look at each of these now.

River management strategies have costs and benefits.

Costs are the negative impacts or expenses associated with planning, building and maintaining a scheme.

And benefits are the positive outcomes, especially in relation to the flood control, erosion prevention or land use.

So for each of the strategies we're now going to look at, we're also gonna consider the costs and benefits of each.

Let's look first at embankments, sometimes known as levies.

You can see here that the arrow is pointing to a raised area next to the river.

These are made usually from earth, possibly from concrete, and the idea is that they raise the river banks.

It means that the river channel, when it's at a time of high flow, can hold more water within it instead of it spilling out onto the surrounding land.

There are benefits to it.

It is raising the river banks, which is increasing the channel capacity.

It's relatively cheap to construct, as it can use material dredged from the river.

There are also costs.

It needs regular maintenance, as they may be eroded or weakened over time, and sometimes at very, very high flows, the flood water might even overtop them, and then it becomes difficult for that water to flow back into the river.

Here we have an image of a flood wall.

Now, this you can see, is a strong vertical barrier, which is built alongside the rivers, and it's often found in towns and cities.

It's again, trying to increase the capacity of the river channel in order to allow it to hold more during flooding and therefore, it's protecting businesses and homes.

Andeep is saying, "It looks a little bit unnatural," and so it's changing the river landscape.

However, the benefits are that it is strong physical protection for urban areas.

So urban areas often have a high economic value, and so therefore they need really reliable protection.

It lasts a long time if it's well maintained.

They're made out of concrete, so it's very difficult to erode them away, but it needs to be made sure that it's repaired and maintained.

The cost to it is it's very expensive to instal and look after, and it's stopping natural river processes, so it's preventing the river from having any natural banks along that side of it.

Little check for you now.

Have a look at this image here.

Can you remember what type of hard engineering this is? And can you find two correct benefits of the strategy in the little table below? So pause the video and come back when you're ready.

I hope you could remember that they were embankments or levies, and that the two benefits of them are that they increase channel capacity by raising the river banks and they're relatively cheap to instal because they're often made for material that is dredged out of the bottom of the river channel.

Let's have a look now at flood relief channels.

So these are channels that are artificially made near to the river that can have excess water diverted into them when we have high flow in the main river channel, a bit like a store of water when it's needed.

The benefits to it is that it protects urban areas by lowering the water levels in the main river.

And another benefit is that it could be used for recreation and it's also providing a habitat for some wildlife.

The cost is very expensive to build.

You need to find space, so you're using land within an urban area for this instead of other economic uses.

And in doing so, it can damage habitats and ecosystems and it can cause because of the coarse land use, change.

So you might be changing the use of that land in order to create this flood relief channel.

Flood barriers.

These are movable barriers that can be raised during storm surges or high tides, and they block flood water from reaching vulnerable areas.

And these are often found in the lower courses of rivers where you've got the tide coming from one direction and the river moving in the opposite direction.

This image here shows the Thames barrier in London, and we can see a few of its 10 steel gates.

And those gates are raised to block river during flood threats and that prevents a storm surge from flowing upstream, and it has successfully been used 200 times since 1982.

And in doing that, protected millions of people and billions of pounds worth of property.

So we can see there that they are a very viable option in areas where we've got tidal movement of water and the river flowing.

However, the benefits and costs need to be considered.

It does protect large areas and it's fairly reliable during extreme weather.

However, it's very expensive to build and to look after to maintain, and there's a flood risk if they're not closed in time.

Another check for you now.

Which of these are costs of hard engineering strategies? A, very expensive to construct and maintain.

B, strong physical protection for infrastructure.

C, it damages ecosystems. Or D, it increases the risk of flooding elsewhere.

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

Did you think of these three? Expensive to construct and maintain.

So each of them are fairly expensive and need constant maintenance, which takes a lot of money.

They may damage ecosystems because of the changed land use, and they may increase the risk of flooding elsewhere.

Now Task A for you.

Can you complete the summary table for these two hard engineering strategies? Flood walls and flood barriers.

So can you describe what they're like and what they do, their purpose, and include some of the costs and benefits? Pause the video and come back when you're ready.

Your table might have ended up looking something like this.

Flood walls, strong vertical barriers built alongside the rivers, especially in towns and cities to prevent water from entering homes and businesses.

However, there are costs to them.

They're expensive to instal and maintain and they restrict natural river processes.

The benefits being that they provide good physical protection and they can last a long time.

And then for flood barriers.

You should have written that they're movable barriers that can be raised during storm surges or high tides and they block flood water from reaching the vulnerable areas.

The cost to them however, are very expensive to build and maintain, and there's a risk if they're not closed in time, that flooding happens.

Benefits, however that they protect large urban areas and they're reliable during extreme weather.

Well done if your answer looks similar to this one.

Right.

Let's think now about the costs and benefits of soft engineering.

Soft engineering is a river management approach that uses natural processes and landscape features to reduce the risk of flooding and erosion.

It's often less expensive, more environmentally friendly, and more sustainable than hard engineering.

Some examples are flood plain zoning, flood plain retention, and river restoration.

So let's have a look at these three.

Jacob says, "So soft engineering must be a better option than hard engineering.

It is less expensive, more environmentally friendly and more sustainable." But Alex says, "I think it will have some costs too, otherwise it would be used everywhere.

Its benefits might vary depending on the location and scale of flood risk." Well done, Alex.

It's good to think that there must be costs and benefits to each of these strategies, hard and soft strategies.

Flood plain zoning is development being restricted in certain locations on the flood plain by identifying which areas have the greatest risk.

The environment agency collects data in order to produce maps like this one of Shrewsbury, and it helps us to understand which areas have the highest risk of flooding.

So we can see here, Shrewsbury is built on the flood plain of a river, and large areas of the town have a high or medium risk of flooding.

So by using flood plain zoning, we can control the land use on flood plains and restrict development in high-risk areas, which hopefully will reduce damage and any problems for vulnerable areas.

The benefits to it is it keeps people and buildings away from flood-prone areas and it's a very low cost.

However, it limits the amount of land that is available for development, and it can be hard to enforce when there is a high demand for that development.

So if they need the land, they may have to use it and hopefully find ways to protect it.

Which of these is a soft engineering strategy? Flood barriers, flood plain zoning or flood relief channels? Pause a video and come back when you've decided.

I hope you remembered it was just the flood plain zoning.

If you think about the flood barriers, the example we gave was in the River Thames near London, the movable barriers that can be closed.

They are definitely a hard engineering option.

They're very expensive to instal and maintain.

And then the flood relief channels are channels that are built near to the main river in order to take excess water during flood times.

Well done.

Let's look now at river restoration.

So if we restore a river to its natural course, we're removing any artificial embankments or flood walls, for example.

And we can see here the River Cole is flowing through a flood plain in a series of newly-created bends.

So by introducing these natural formations of meanders, we're lengthening the river and slowing its flow, and hopefully by doing that, reducing the flood risk.

The third example of soft engineering is flood plain retention.

And this means that we're preserving or we're restoring the natural flood plain.

The flood plain is the flat area next to the river in the lower course.

And when a river floods, it naturally flows out onto that flood plain.

By restoring or preserving it, we can see that the excess water during floods is temporarily stored on that flood plain, and this helps to reduce the peak river flow and protects areas downstream.

The benefits and costs of both of these are that flood plains store water, which might otherwise flood properties downstream, so it's providing a natural store of water, and it provides long-term environmental benefits.

By restoring or maintaining a natural landscape, we're increasing the biodiversity of the area.

However, flood plains can only store so much, so the flood risk is reduced, but it's not eliminated.

And it can't be combined with the development of floodplains, so it has to be something that's left naturally and we can't use that area, which can be quite problematic in certain urban areas.

Let's try a true or false.

Hard engineering is always a better option for river management.

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

Try to think of your reasons why, too.

Hopefully you said false, but why? You may have come up with something similar to this.

There are many benefits to using soft engineering strategies in river management, including increasing biodiversity and restoring natural landscapes and processes.

However, some of these strategies take a long time to work and they might not be effective in extreme floods.

Have a look now at your second task.

This area around the River Cam is at risk from flooding.

We can see here a map showing you the land use of the area and then a second map on the right-hand side, which shows you its risks during floods.

And we've got, it's an area which experiences high and medium flood risk.

We can see on the left that there is a mixed land use, houses, business and parkland.

So what two river management strategies would you suggest using to reduce that flood risk? Try to give reasons for your choices.

These strategies can be hard or soft engineering.

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

Your answer might have included embankments as a choice.

Those are raised banks built along the river to prevent it from overflowing during periods of heavy rainfall.

So in this area of the River Cam, embankments would be effective in protecting both residential areas and businesses from flooding, which is particularly important in urban areas where property damage could be significant.

Embankments are relatively cost-effective compared to the other hard engineering solutions like flood walls, and they can be built at varying heights depending on the flood risk.

In the areas of parkland and other low-risk zones, I would recommend flood plain zoning and flood plain retention.

This would involve restricting future developments in areas that are at risk of flooding, particularly on the flood plain.

And by keeping development away from these areas, the risk of damage during flooding events is reduced, and this retains the flood plain so it can act as a natural storage area for excess water during a flood.

This combination of hard engineering and soft engineering would offer a balanced and sustainable solution to flood management, ensuring the protection of both people and the environment.

Your answer may have chosen those same strategies or you may have chosen different ones.

Just make sure that you've given reasons why you think they are good choices.

Well done.

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

Hard engineering, for example, flood barriers and embankments provides immediate flood protection, but it is expensive and it can harm the environment.

Soft engineering, for example, flood plain zoning or river restoration, is sustainable and cheaper, but it may not offer quick results.

Both have costs and benefits and often a combination of both can provide the most effective protection whilst also being more sustainable.

The choice of strategy depends on the location and land use, with urban areas, expensive property, often selected for hard engineering and rural areas, which have a lower value land, selected for soft engineering.

Well done today.

You've worked really hard.

I hope now you feel more confident when discussing the costs and benefits of managing flood risk in different areas.

Well done.

Look forward to seeing you soon.