﻿Hi everyone and welcome to today's session. So, what we're going to be having a look at today is the strategies that you can use to reduce the risk of desertification. Now there are four that we're going to be taking a really good look at. We're going to be practising some exam skills today. We're doing lots and lots of interesting things. So before we start, can I please ask you to grab a piece of paper, a pen and a pencil and a ruler. And then as I say every single session, turn your phone off, make sure you're somewhere nice and quiet that you can concentrate and let's start and have a look. So our title for today is strategies for reducing the risk of desertification. What I'd like you to do is to write that at the top of your page, underline it with a ruler. Make sure you're super careful with your spelling of desertification, only one S not two. I sometimes have a tendency to put two S's in it and then that spells does a dessert, oops. Okay, so let's make a start. What we're going to be having a look at then is these four strategies that we can use to reduce the risk of desertification. Now, before we start, it's probably worth me saying this is incredibly important. Over 1/3 of the world's land mass is at risk of desertification. And a huge number of people live on that land and are dependent on it to grow their crops, to feed their livestock and so if we don't manage it, the impact of that could be enormous. It could have huge effects on food supply, creating famine and all sorts of other problems. So what we have to do is think about how we can manage the land on the edge of hot deserts sustainably. And the strategies that we can put in place are the following. So you can do soil management, water management, tree planting and something that's got appropriate technology. Now you may have come across appropriate technology before but I'm going to explain a little bit about the kind of tech that you can use in these areas, which can actually halt that process of desertification. So let's dive straight in and have a look at soil management. So the soil that is found on the hot, sorry, on the edge of hot deserts is critical because we know that in desert environments, there are very low levels of rainfall. There is hugely high temperatures, which are quite extreme. And as a result, there is very little soil because there isn't a lot of plant matter so it doesn't die, it doesn't decompose as leaflets are creating soil. The land around the edges of deserts, that's where the soil can be found but desertification is starting to turn some of that land into desert. Now, two ways that the soil can be managed is by one, leaving areas of that soil to rest. So farmers can be taught essentially not to continually graze their animals on the same plot of land or not to continually grow crops year on year on year on the same plot of land. And essentially they leave the land to rest in between grazing or in between planting crops. And if they do that, the land is able to recover. Not all of the nutrients are removed, not all of the plant cover is removed, which means that the soil stays where it is, it's not eroded by the wind and the rain. Now, the second thing that you can do to manage soil in hot desert environments is actually you can try and replace the nutrients that are being taken up by the crops and you can replace it using compost. Now, if you use compost, compost is high in nutrients. And essentially what that means is plants can continue to grow in that area and hold the soil together. Okay, so we've talked a little bit about soil management. What I would now like to do is check just how much you've understood. So what I've done is write out a paragraph that if you are asked about desertification and you're asked about how managing soil can prevent desertification, this would be the answer but then what I've done is removed some of the words so that you can fill in the gaps. So I'm going to read the paragraph then I'm going to go through the words. Then I'm going to ask you to pause the video and write this out yourself. So managing soil on the edge of hot deserts is extremely important. Leaving land to between planting or can allow the land to recover. This stops too many being removed from the soil, therefore plants can continue to grow. Plant hold the soil together, which prevents soil. So the words I'd like you to use to fill the gaps are erosion, nutrients, rest, roots and grazing. So pause the video now, take your time, write out that paragraph, add those words into the gaps and then we'll come back in just a second to go through the answers. Okay, so hopefully you've had time to do that, let's go through our answers. So managing soil on the edge of hot deserts is extremely important, leaving land to rest, okay? So we leave it to rest between planting or grazing can allow the land to recover. This stops too many nutrients being removed from the soil, therefore plants can continue to grow. Plant roots hold the soil together, which prevents soil erosion. So if we think back to everything we did when we looked at the causes of desertification, that is the key thing here, is about making sure that the soil has enough nutrients so that the plants can grow and then those plant roots compact and hold the soil together so it's not vulnerable to soil erosion. Give yourself a tick for each of the ones that you've got correct. Well done and let's have a look at our second type of management. Okay so for this one, what we're going to have a little at is how to manage water in hot desert environments. And before we do that, I need to explain why we need to manage water. So obviously on the edge of hot deserts, there are still low levels of rainfall. So we're still talking 250 millimetres or less per year. Now what happens is that often that water that does fall is used for commercial farming and commercial farming involves growing crops that can then be sold. And to do that, they normally irrigate the soil. That means that they take water from dams or from rivers and flood the land with it. Now as a result, there is a huge amount of water that's sitting on the surface in those areas. And it then gets evaporated really, really quickly because the temperature is so high. Now when that happens, that evaporation draws water to the surface and it also brings salts with it. Now those salts then sit on the surface of the soil and they can cause it to be incredibly acidic, which affects the soil fertility, essentially the soil is not a great place for then plants to try and grow, is why there are only certain types of plants that grow in coastal environments. Salt is really, really acidic and has a huge effect on a plant's ability to grow. Now what you can do to manage water in the desert is two different things. The first is that you can be smart and only grow crops that require a little bit of water. So there's a species called millet and also olives, you don't need or they don't need a huge amount of water to grow. So if you grow crops like that, then there's less need to irrigate and actually as a result, there's less evaporation of the water and less salinisation, that's salt coming to the surface. The second thing that you can do is use something that's called drip irrigation instead of flooding the surface of the land like they do for surface irrigation. Now what that essentially means is having almost like a hose pipe with little holes in it and the water comes out now and again and it waters the plants rather than flooding the land and allowing the crops to grow that way. Now if you use drip irrigation, it means that actually you're using less water for a start but also surface irrigation can lead to lots of soil being eroded when you add all that water in one go. So drip irrigation is really effective for two different reasons. One, because it uses less water but two, because it is better than surface irrigation, which can lead to lots of soil being eroded by the water in one go. Let's see what you've learnt. So, the question that I'm going to ask you is this, suggest how water management can reduce the risk of desertification on the edge of hot deserts and it's worth three marks. Now remember, we've talked about this previously, suggest is a lot like the word explain. So it's essentially saying, give reasons why water management can reduce the risk of desertification. And you could choose to write about one of two things, you could either write about using crops that use less water or you could write about drip irrigation, it's up to you. Now remember if this question is worth three marks, they're asking you to double develop your explanation. So to do that, I want you to use the connectives. This means, because, as a result, then. So, pause the video now but three or four minutes, have a go at answering that question. How does water management reduce the risk of desertification on the edge of hot deserts? Okay, well done. Now that was quite a tricky question. So I want you to listen as I go through my answer and you can then see where you would have got the marks. So one strategy for managing water in areas under threat of desertification is to plant crops which require less water such as millet and olives. This means that less water will be needed and drip irrigation could be used. This means less soil erosion will occur as lots of water will not be added to the ground too quickly, which reduces the threat of desertification. And you can see what I've done in my answer is I've combined the idea of using plants that require less water and using drip irrigation. So if you did that in your answer, that is absolutely fine. Go through, highlight anywhere where you've used the key term and put that, where I used the pink but you can use whichever colour you prefer. And then I would like you to go through and highlight your connectives. So anywhere where you've connected one point with another, this means, this means, which, because, therefore, highlight that in a different colour please. Right, pause the video if you need to, if you're good to go, let's move on and have a look at tree planting. So this is my favourite of all the strategies for preventing desertification. So, tree planting in hot deserts. Now this might seem counterintuitive in the sense that there's high levels of sunlight but not a lot of rainfall and trees need a lot of rainfall to be able to photosynthesize. But tree planting is amazing because it can prevent desertification in two different ways. So the first thing that trees can do is they can act as a windbreak, which protects the soil from wind erosion. The second thing that they can do is that the roots of the tree can stabilise the sand, which prevents the desert from encroaching, as in moving onto farmland that's on the edge. Now, there is a huge project that they've got planned across Africa which is called The Great Green Wall. Now they're not looking at building an actual wall, it's essentially a tree planting project and they are going to plant trees for over 7,600 kilometres along the edge of the Sahara desert, in that place that I told you about before which is called the Sahel. Now some of those that wall or some of the trees planted at that wall will be up to 15 kilometres wide. And the reason that they're doing that is prevent the Sahara desert from travelling any further South and any further North in certain places so that it doesn't affect the farm land on the edge of the desert. Now, if you want to take some notes about this, just pause the video, not a problem. Okay, so what I'd like you to do for this activity is to draw yourself a picture of a tree, okay? You're going to draw yourself a diagram. And then I'd you to add the two following annotations to your diagram, which is, trees act as windbreaks to protect the soil from wind erosion and tree roots can stabilise the sand to prevent the desert from encroaching on farmland. So draw your picture of a tree, add those two annotations, draw the arrows to where you think it's appropriate on your diagram. And then we'll have a look at the answer in just a second. Okay, so did you get? Now, I think this one's fairly simple but essentially tree roots can stabilise the sand to prevent the desert from encroaching on farmland. Your arrow should be pointing to the roots of your tree and then trees can act as windbreaks to protect the soil from wind erosion, that it should be pointing up at the leaves, okay? So that is your diagram of tree planting. So we've just got one more strategy to have a lookout now, which is what we call appropriate technology. So appropriate technology is all about using technology that is cheap, that is sustainable, as in the local people can make it and they can maintain it. And that made of local materials that can help reduce the threat of desertification. Now in this area, in the Sahara and in deserts around the world, one of the biggest causes of desertification is the fact that trees are deforested or removed for fuel wood so that people can cook. Now actually, what you can do is sustainable, sorry, appropriate technology which is sustainable is that you can put something in place that prevents people from doing that, that reduces their dependency on firewood and have a look at this photograph 'cause this is quite amazing. These are what we call solar cookers. Now, what you can see is actually they're like mini solar panels and they can use the heat to actually transfer that to energy which can be used for cooking. If you use a solar cooker, there's no need to cook on an open fire so that reduces the risk of deforestation. The second strategy that can be used is something called a stone bund and I love the name of this, a bund. Now essentially a stone bund is a stone wall but they're built in a way that can stop soil from either being washed or blown away. And again, that can prevent soil erosion. Now these stone bunds, they're really small, they're built out of local stone by local people. They're affordable, they are easy to maintain. So it's an appropriate type of technology that reduces the threat of desertification. So what I would like you to do, I would like you to decide which of these statements are true and which are false. So it is expensive and hard to maintain. Solar cookers reduced rates of deforestation. It is cheap and the materials to make them are widely available and stone bunds allow more soil to be removed by wind and rain. So have a look at the picture, think by what I said, write out those sentences, which ones are true, which ones are false. Pause the video and I'll see you in just a second. Okay, let's go through the answers then. So you should have had, appropriate technology, it is expensive and hard to maintain, no, that is not true. It's the opposite, it's cheap and it's easy to maintain. Solar cookers reduced rates of deforestation. Now that is true because people don't need to cook on open fires anymore. They can use their solar cooker instead. It is cheap and the materials to make them are widely available, that is true. And then stone bunds allow more soils to be removed by the wind and rain. We'll actually, that's the complete opposite of their design. They are designed to prevent soil from being removed by the wind and the rain. Right, well done. So we've looked at our four strategies to reduce the risk of desertification. We looked at soil management, we looked at water management, we looked at tree planting and now we've looked at appropriate technology. So this is the last thing I'm going to ask you to do today. I would like you to categorise the following as one of the four types of management that could be used to reduce the risk of desertification. So essentially we've got our four types, which one of these is which. So we've got solar cookers are used to reduce deforestation. Trees can act as windbreaks, which protect the soil from wind erosion. Drip irrigation uses less water, which reduces the risk of soil erosion. Compost can be added to the soil to restore nutrients. So write each of those sentences out please. Decide which managements type you think they are and then I'll see you back here in just a second. Okay, well done, let's go through the answers. So solar cookers are used to reduce deforestation, that is appropriate technology. Trees can act as windbreaks, which protect the soil from wind erosion, tree planting. Drip irrigation uses less water, which reduces the risk of soil erosion, that is water management. And then last but not least compost can be added to the soil to restore nutrients, that is soil management. So give yourself a tick for each one that you got correct. If you've got any wrong, then just switch them around now and make sure that you're super clear on this. And then that brings us almost to the end of our session. Okay, well done today. So we have been on quite a journey. We have looked at the four strategies that can be used for reducing the risk of desertification. And all I'd like you to do now is to go through your work and just to highlight anything that you've got down today that you think is really important. The names of the four strategies and understanding just a little bit about how each of them work is really, really key. There's a quiz for you to do after this, well done and well done for reaching the end of our series of lessons on deserts. And hopefully I'll see you soon.

Explain how water and soil management, tree planting and the use of appropriate technology can reduce the risk of desertification.

Geography

Y11 Geography

Key Stage 4

Year 11

Strategies for reducing the risk of desertification

Hot deserts

UNIT

Physical characteristics of hot deserts

Interdependence in hot desert environments

How do plants adapt to the hot desert environment?

How do animals adapt to the hot desert environment?

Development opportunities in hot deserts: The Sahara

Challenges for development in deserts

Causes of desertification: Population growth

Causes of desertification: Soil erosion

Lesson overview: Strategies for reducing the risk of desertification

Intro Quiz

Video

Exit Quiz

Transcript

9 lessons in Hot deserts: