Lesson video

Hi everyone.

My name is Miss Dhillion.

And last lesson we were learning about why rivers are important to people.

Can you give me one reason why rivers are important to people? Okay, so you might have said they're useful for transportation or that they're really useful for agriculture because the soil near rivers is really fertile or you might have even said, it's very useful for the fishing industry and also the tourist and travel industries.

So there are lots of positives of rivers and the impact it can have for people.

In the lesson today, We will be exploring the question, what happens when a river floods? This is what the structure of our lesson is going to look like.

We are going to go through the star words, then we're going to learn about what a flood is, then we will learn about the physical causes of floods.

Then we will look at the human factors, which increase the flood risk and finally, we will finish by looking at the positives and the negatives of floods.

Please make sure you have all the equipment that you will need for today's lesson On the screen, you can see the star words for today's lesson.

Let's say them out loud using my turn, your turn.

Are you ready? Floods, banks, rainfall, snowmelt, infiltration, urbunisation, impermeable, deforestation, agriculture.

Okay, team.

There's lots of new and long words on the page, but don't worry.

We will go through them as we move through the lesson.

So in today's lesson, we are going to be looking at physical and human geography, which are two strands of geography.

We will be looking at the physical causes of floods and these include rainfall, snow melt, and the sleep slopes.

Then we will also be looking at human factors which are increasing flood risk.

And we will be looking at urbanisation and deforestation.

But first let's start by understanding what a flood is? Let's read the definition together.

When a river's water spills over its banks, which is the sides of the river and spreads out over the surrounding area.

So, something that is very important is to understand that the water is spilling over.

So there's too much and it's spilling over the banks, which are the sides of the river.

And what happens as a result is that water spills over into the surrounding areas.

Good job.

I would now like you to pause the video so you can complete this task.

Let's see if you can remember the definition of a flood.

Here is the correct answer.

How did you do team? Did you manage to remember the definition of a flood? Thumbs up if you did.

Now, we're going to look at the causes of floods.

A river can flood due to a variety of reasons.

We will start by looking at the physical causes of flooding.

Firstly, a river can flood because of heavy rainfall or when there has been rainfall for a very long period of time.

Secondly, another physical reason or cause for flooding is snowmelt.

If snow and ice suddenly melt in the mountains, this can lead to rivers flooding.

And this is because all the ice that melts turns into water and fills the rivers, causing them to flood.

Thirdly, another physical cause of floods is steep slopes.

If the river is surrounded by very steep land, the water can run down really, really quickly to the river.

And this can cause the river levels to rise.

Steep slopes tend to reduce the amount of infiltration of water into the ground.

My turn, your turn.

Infiltration.

Infiltration of water is when the water enters the soil.

So because these slopes are very steep rather than the water having chance to absorb into the soil, it actually runs down really fast to the river.

And this causes flooding.

I would now like you to pause the video so you can complete the task on the screen.

Here is the answer.

So all of these were physical causes of floods except urbanisation.

So well done if you spotted that.

Now we're going to look at the human factors, which increase flood risk.

Humans have increased flood risk due to urbanisation, which is the building of towns and cities.

My turn, your turn.

Urbanisation.

This is because towns and cities have impermeable surfaces.

My turn, your turn.

Impermeable.

Good job team.

So impermeable means that the surface does not allow water to go through them.

So if you look out into the cities and towns, most of it, has floor that is concrete.

This is very different to soil, which allows the water to sip in, but concrete does not let the water do this.

So what happens is that the water carries on running on the pavement rather than going through the pavement.

So what happens when there is very, very heavy rainfall? Is that the water has nowhere to go.

Humans are also increasing flood risk by cutting down lots of trees.

And this is known as deforestation.

Trees are very useful because they catch lots of rain and they slow down the movement of water on the land, which helps to reduce flooding.

Therefore, cutting down trees prevents this from happening.

Pause the video now to match up the picture with the correct keyword.

Here are the answers.

Deforestation is the cutting down of trees and urbanisation is the building and extending of towns and cities.

Well done, if you matched those up correctly.

Now that we have covered all the physical causes of floods, as well as the human factors, which can increase the risk of floods, I would now like you to sort these causes into the correct heading.

The two headings are physical causes and human factors.

Pause the video now to complete this task.

Here are the answers.

Did you manage to order most if not all of those correctly? Well done if you did.

High five Jogva.

Now we're going to stop by looking at the positives of flooding.

And then we will go on to looking at the negatives.

So rivers have always flooded and humans have actually depended on rivers flooding.

This is because each time a river floods, it deposits, which means it leaves behind very important sediments and nutrients on the surrounding land.

This makes the soil very rich and very fertile.

Rich and fertile soil is very important for successful agriculture or farming.

If the soil is fertile, you can grow lots of crops on that soil.

However, on the other hand, there can be some negatives of flooding and it can cause a lot of problems for the people who live very close to the river.

Each year homes are destroyed and people lose their lives when rivers floods.

Once floods have happened, because they destroy so many houses and buildings, cleaning up flooded areas and rebuilding the communities takes a very long time and costs a lot of money.

For this task, I would like you to write what one positive and one negative impact of flooding is.

You can use the pictures on the screen to help you remember what those reasons are.

Pause the video now.

And don't forget to write in full sentences.

Here is the answer.

Take a few moments to read through the positive and the negative.

Okay, team.

So the key positive is that the river deposits really important sediments, which helps farmers grow their crops.

And this is really important for successful agriculture.

And then the main negatives is that it destroys people's homes.

It takes lives and it costs a lot of money and time to rebuild the areas in which the flood has occurred.

Now, one strategy that people use to prevent flooding is building a dam.

You can see a dam in the picture on the screen.

A dam is a barrier that stops or restricts the flow of water.

We are now going to look at a case study.

We are going to be learning about the Aswan High Dam, which is built across the River Nile in Egypt.

On the screen, you can see the continent of Africa.

We are going to be zooming in to the country of Egypt.

On the map, you can see where the Aswan High Dam is, and this is the red pin on the map.

In the map, you can now see a blue rectangle.

And in this, you can see a reservoir or lake that is built up behind the dam.

Now we're going to read some information about the Aswan High Dam.

Let's look at the text more closely.

Are you ready to read it with me? The reservoir built up behind the dam is an important store of water during the times of drought, which is a lack of rain.

The dam also allows electricity to be generated and it's helped stop the annual floods, which has caused a lot of problems. However, the dam stopping annual flood has led to a gradual decrease in the fertility of the farmland.

The annual flood brought important nutrients to the farm lands along the river.

Farmers must now use lots of irrigation, which is watering systems to water their farmland.

Okay, team.

So the reason we're looking at this case study is it's very important to highlight the positives, but also the negatives of instilling a dam, which will help prevent flooding.

So in the text, you can see the pink, which is talking about the positives.

So it says that the reservoir, which is created as a result of the dam is a very important store of water.

The dam also allows the local people to create electricity, which is of importance for daily life.

And it's also stopped the annual flood, which happens every year.

However, In the purple we can see the negatives of this dam.

The key negative point is that the dam has stopped the floods, which has stopped important nutrients being deposited onto the farmland.

Therefore this is impacted, the agriculture or farming, but in a negative way Is now your turn to write down what you think about controlling rivers.

You are going to answer the question, should all rivers be controlled to prevent flooding? For this task, you will need to use a text on the previous slide.

So on this page, to help you write your answer.

So you can always go back to that previous page to help you write your answer.

You can also use the positives and negatives of flooding, which we learned about earlier on in the lesson.

For the last sentence here, where it says, overall, I think that.

This requires you to write down your own opinion.

So there is no right or wrong answer.

Just what you think.

Let me share an example of what your answer might look like.

So let's have a look at my model example.

So this is my answer.

Let's read it together.

On the one hand, I think that rivers should be controlled to prevent flooding because flooding can cause a lot of destruction.

For example, destroying homes and taking lives.

On the other hand, I think that rivers should not be controlled to prevent flooding because as we can see, in the example of the Aswan High Dam, preventing the annual flood led to a decrease in the fertility of the farmland, which would normally benefit from the nutrients that were deposited by the river.

Overall, I think that rivers should be controlled to keep people and their homes safe, but with careful consideration of the potential disadvantages and how these can be overcome.

Okay, team.

So now you can see how I have used the sentence stems to write an answer.

And I have also referred back to the Aswan High Dam as an example.

Now it's your turn to write your answer.

Pause the video now to complete this task.

Okay, team.

That is now the end of today's lesson.

And I really hoped you enjoyed learning more about what happens when a river floods? Bye everyone.

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