Intro Quiz: What are the features of a river's long profile?

Video: What are the features of a river's long profile?

﻿Hello and welcome to the next lesson in this rivers unit. Today we are going to look at how a river changes along its course. So we're going to look at how a river changes from its source, so where it starts in an upland or mountainous area all the way down until its mouth, where it meets the sea. And along a river, we get very distinct features and that's what we're going to examine today. So I invite you now to pause the video, go and get all the normal equipment that you need. So exercise book or paper, pens, pencils, that kind of thing. And when you're ready to begin, hit play. Hello and welcome to this next lesson in the rivers unit. Today, we are going to be looking at what the key features of a river's long profile are. And a river's long profile is the distance from its source in an upland or mountainous area, all the way down to its mouth. And along this long profile, we get very distinct features. And that's what we're going to examine today. So you need a pen and pencil, an exercise book, or a piece of paper. And when you've got those resources ready and you're somewhere quiet where you can focus, hit play, and we can begin. So we're going to learn about how a river changes from its source in an upland or mountainous area to its mouth. And we call this distance from source to mouth, the long profile, and along this, we find very distinct features. And that's what we're going to spend time looking at today. On the right hand side, you've got a side on of a river's long profile, and we're going to investigate this in more detail. So your first task today, using the words below in the grid, add the correct labels to the diagram for A, B and C. Deliberately, I've taken the labels out. Can you work out which of the words from the grid matches which of the letters? So pause here to complete this task. Okay, so here are the answers. We're thinking about our drainage basin system. A was precipitation that's being inputted to the system. B, interception, the leaves of trees and other vegetation trap precipitation from reaching the ground. C, there's an output from the system is evaporation. So check that your answers are a hundred percent accurate and complete please here. There's some key terminology, that I'm going to talk through today, that's really, really important that you have an understanding and awareness of. What I suggest you do as I read these key terms out, that you make a note of them in your notes from today. So you write them down in full. So erosion is the wearing away and removal of the riverbed and banks by the power of the water. Rivers can be very, very erosive and very powerful. Flowing water has lots and lots of energy and it's able to do lots of erosion. There are two kinds of erosion that take place within a river. Vertical erosion is erosion which takes place downwards or vertically. So I've indicated that with a down arrow. Lateral erosion is erosion which takes place sideways, which wears away the side of the river banks, widening meanders in the river and I've represented that with arrows pointing sideways. So what I suggest you do, pause here to note down those key bits terminology, please. Another new word that you need to be aware of today is deposition. So it's a different process from erosion. Deposition is when a river loses energy and therefore drops the sediment and rocks that it's carrying, and sediment and rocks that it's carrying, we call its load. So deposition takes place when a river loses energy and therefore drops the sediment and rocks that it's carrying. And you can see that on the figure in the right hand side, you can see small pebbles that have been deposited on the river bank. So I've said before, we're looking at the long profile of a river. This is a river all the way from its source, where the gradient is steepest, to its mouth, where the gradient is very, very gentle. And a river is split up into three sections or courses. So we call each section a course. The upper course, you can see marked on the figure. The middle course and the lower course. And you're going to draw your own detailed diagram of a river's long profile, which is really, really exciting. So you're going to watch this video, watch me add detailed bits to my own diagram and then you can do the same to your own diagram. So you are going to draw a really, really detailed diagram of a long profile or a river. First of all, what you need to do, either take a piece of paper or just an exercise book. Either is fine. Turn it landscape, so sideways. I'd like you to write at the top of your page, long profile of a river, and then draw what I've done. So I've drawn an outline of a river's profile and split it into three sections. Please do that now. Next, you need to label the different sections. So the first section is the upper course. Second section is the middle course. Final section is the lower course. So what I suggest you do is pause this video as you go through it so your diagram looks like mine. I'm going to model and explain it step by step. So pause here until your own hand-drawn diagram looks like the one on the screen. I'm going to talk through what happens in the upper course. What I suggest you do is listen to my explanation first time round, then rewind it and add in these details to your diagram. But I suggest that you just listen first of all. So in the upper course, we know we find the source. So I've written the source at the top there. That's the beginning of the river. In this upper course, vertical erosion is taking place. So that's erosion downwards. So that's why I've done sort of that red X over that small overhang, because the river would have eroded downwards into that. In this upper course, we have a very, very steep gradient. So the slope is very steep and the river is very narrow and shallow. If you look at the top of the diagram, I've drawn a cross section, a slice through the river. So you've got to imagine the river's flowing out towards you, out from the screen. So you can see there, the sides of the river are very, very steep. So we know we have a steep gradient and it represents, or you can sort of see that it represents the shape of a V. So you would describe the valley shape in the upper course as V shaped. And we also get waterfalls as features in this river. So what I've done is I've done a cross section for you of a river at the top, and I've also put in black in those two bullet points, two features that we get in this upper course. So I'd now like you to pause the video and add these labels and details to your own diagram, please. So we're going to spend some time looking at the middle course. Again, I suggest you listen to this explanation, first of all, before making additions to your own diagram. So in the middle course, we get lateral erosion. Remember this is different from vertical erosion because it's erosion sideways. We also get some deposition, which is where the river is depositing or putting down the sediment and rocks that it's carrying. The river, in this section of the river is also beginning to get wider and deeper. And you can see that at the top of the screen there where I've drawn the cross section of the river. The river is definitely wider here than it is in the upper course. We also get two key features in this section of a river, a meander, it's quite an odd word, a meander. That's a bend in the river and an oxbow Lake. So pause here. Add in those additions to your diagram, please. Finally, we're looking at the lower course of the river. We know this is where the river meets the sea. So I've drawn in the river mouth at the bottom. I suggest you do the same on your diagram. In the lower course we don't, we get very, very little erosion. Deposition is the key process that's taking place. So lots and lots of deposition takes place. You get a very flat gradient and the river is widest and deepest here. So you should be able to see from the cross section, for example, that the river is clearly much, much wider than the middle and the upper course. We get two key features in this section of the river. Flood plains, which are flat areas of land, either side of a river, which flood frequently. Often in the news, you hear about controversies with new housing being built potentially on flood plains. So that's what a flood plain is. And then, a levee which is a raised embankment either side of a river. So pause here to note down some of those key details for the lower course, please. Finally, along the bottom, I've drawn an arrow with the descriptor, erosional features. So features that are found in the upper and middle course are formed by erosion and that's what that label indicates, whereas features in the lower course and some features of the middle course are formed by deposition. So we call those depositional features. Meanders and an oxbow lakes, you can see are formed by combination of erosion and deposition, whereas floodplains and levees in the lower course are just formed by deposition, and waterfalls and V-shaped valleys in the upper course are just formed by erosion. So as a quick check, you've got a small task to do. For each of the following five statements, say which course of the river they apply to. Is it the upper middle or lower? So write one, two, three, four, five, in your notes and write which course of the river they apply to. Pause the video here to complete this task. Okay, let's have a look at the answers. So number one, the river is narrowest here. That's in the upper course. We get V-shaped valleys where the river will be very, very narrow. Number two, the river is widest here. That's the lower course. Remember from your diagram, you should clearly be able to see that. And number three, lots of vertical erosion has taken place here. That is the upper course. That's erosion downwards. And number four, meanders and oxbow lakes are generally found here. That's the middle course. And number five, the gradient or slope is steepest here. That is the upper course. Well done If you got five out of five. Please mark your work here. Check for accuracy and completion. Pause the video now to do that. Okay, so you've got your own diagram now, but I'm going to show you some photographs from these different courses of a river so you can visualise what these features look like. Some of you may even be quite familiar with what lots of these look like. So this photograph is showing you a V-shaped valley. The river you can see is very narrow. It would be very shallow. We know that in a V shaped valley and in the upper course, we've got erosion downwards, and we call this vertical erosion. Here we've got another feature that's found in the upper course. This is a waterfall. Waterfalls again, are formed by vertical erosion. So here we are in the middle course, we can see a meander. So this is when a river bends around. The river, compared to the upper course, is beginning to get wider and deeper. We know as well that we get sideways or lateral erosion taking place in the middle course. In particular, the outside bend of the meander that I've labelled there. In the lower course the river is at it's widest and deepest. Visually, that should be really repaired using that photograph. In the lower course as well we get what's called a flood plain, which is a flatter area found by the side of the river, which floods frequently, and this forms from the process of deposition. So we call it a depositional feature. Okay, so as a quick check, for each of the following statements, write down whether they are true or false. If they are false, write down why they are false. So pause the video here to complete that task, please. Okay, so here are the answers. Number one, not much vertical ersion takes place in the upper course. This is false, absolutely wrong. Lots of vertical erosion takes place here. This is in fact how waterfalls form, for example. Number two, valleys in the upper course of a river are v-shaped. That is true. That's to do with the amount of vertical erosion that's taken place. Number three, meanders are where lateral erosion is taking place. That is true. Number four, in the lower course, the river is very narrow and shallow. False, the river is widest and deepest here. I've shown you a photograph earlier on in the lesson, which shows that. Number five, as you travel down a river's profile, it's gradient would decrease. True. It becomes much, much flatter. So pause here. Please mark your work. Check for a hundred percent accuracy and completion. A big well done if you've got five out of five. Now this brings us on to our main task for today. I want you to imagine that you've been on geography field trip and walked from a river source to its mouth. Hopefully the weather has been kind. You must write a letter describing how the river changed through its different courses. Use your completed diagram that you've got and the success criteria below to write that letter. So I would like this letter to contain four things. That you talk about the relief of the land for each course, so how steep is the gradient. Secondly, that you refer to the shape and depth of the river. Is it narrow? Is it deep? Is it shallow? Is it wide. Thirdly, that you include at least one process for each course. So is erosion taking place? In particular, what kind of erosion? Lateral or vertical erosion? Or is deposition the main process taking place? And then fourthly, at least one feature is mentioned in each course. So I'm going to show you next a modelled example that we're going to mark together before you then have a go at answering this. So let's have a look, whether this answer meets the success criteria. So please read it with me now. "Dear friend, "I have had a very tiring day "walking from the source to the mouth. "I saw some spectacular things. "For example, in the upper course, "the land was very steep. "Here the river was narrow and my teacher says "vertical erosion happens in this part of the river. "This is erosion that goes downwards. "In the middle course, the land gets much flatter "and there are meanders. "In the lower course, the land gets really flat." So let's have a look. What feedback would we give to this student, who's written this answer? Well, where they talk about the upper course, they refer to the relief and the shape of the land. So that is very, very good. However, they don't give any details on the river's depth. They say the river was narrow, but not that the river, how deep the river was or whether it was shallow. They include the process of vertical erosion but they don't give a specific feature they might see, like a waterfall. The section on the middle and lower course is too brief. They only really mentioned relief. They don't talk about processes, which are taking place there, or in fact features that they would find. So, using that modelled example that I just talked through and your completed the diagram and the success criteria, I'd like you now to write this letter. It should take you, I would say 12 minutes. So give yourself 12 minutes, starting now. Well done, that's the end of the lesson today. In this lesson, we have looked at a river's long profile and how a river changes from its source to a mouth. And we get very distinct features at each stage of the river. Your job now is to complete the quiz. This will help consolidate your learning. Next lesson we're going to be looking at more of these processes, which take place within a river. For example, erosion and transportation. So I will see you then.

Exit Quiz: What are the features of a river's long profile?

Completed: What are the features of a river's long profile?

In this lesson we will be learning how a river changes from its source to its mouth and how distinct features are found in the different courses.

Geography

What are the features of a river's long profile?

Introductory Quiz

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Final Quiz

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