Lesson video

Hello, my name is Mr. Conway.

I'm very pleased to have the opportunity to guide you through today's Geography lesson.

The emphasis in today's lesson is going to be on the use of geographic information systems, also known as GIS.

So let's get started.

This lesson is part of the unit on river landscapes.

By the end of today's lesson, the intended outcome is that you'll be able to use GIS to analyse river catchments and profiles.

Some of the learning about GIS may be new to you, but I'm here to support you all along the way.

To help us achieve the outcome, we need to learn or remind ourselves about certain keywords.

And the keywords for today's lesson are analysis tools, Trace Downstream, Create Watersheds, and Elevation Profile.

Let's look at each one of those individually.

Analysis tools are a range of GIS applications used to support the processing, analysing, and visualising of spatial data.

Now, the next three words are some very useful analysis tools which we're referring to using their proper names, which is why, as you may have noticed, that they're capitalised.

Trace Downstream is a GIS tool which helps us to map the course of a river from a location such as its source all the way to the end of the river.

The Create Watersheds is a GIS tool which maps the drainage basin or catchment of a river and all its tributaries.

And the Elevation Profile GIS tool visualises changes in height above or below sea level along any transect line such as a river course.

Our first learning cycle addresses the question how can GIS be used to analyse a river course and its catchment? And the second learning cycle will explore how we can use GIS to analyse river profiles.

So we're going to look at the first of these learning cycles now.

We can use GIS to visualise and then analyse the physical and human systems and processes associated with rivers.

GIS has the capacity to help us analyse all kinds of aspects of rivers.

For example, GIS can help us analyse physical features of rivers, such as a drainage basin or the watershed around the drainage basin, or smaller features such as meanders.

On the other hand, GIS can also help us to analyse human features or human activities which have impacts on the river.

We need to understand these in order to manage flood hazards and ecosystems such as wetland habitats more effectively.

A key way that GIS can support our study of rivers is by providing us with analysis tools.

These can support the processing, analysing, and visualising of spatial data about rivers.

ArcGIS Online Map Viewer has some very useful analysis tools.

You'll see these very soon in the video demonstrations.

But for now, just remember they're found in the Settings: (light) toolbar, and that tends to be found on the right of the web maps where you will need to click on the Analysis icon, and that looks like this.

And that reveals a hammer icon, which is used to symbolise Tools.

These are the analysis tools, not to be confused with more general tools available in ArcGIS Online.

So these analysis tools include a dropdown section, which is called Find locations.

And in that section, you will find the tools called Trace Downstream and Create Watersheds.

So look out for those things.

The first thing we're going to do is to see how we can use the Trace Downstream GIS analysis tool, and that maps the course of the river, and in this case, it's the River Eden.

The Trace Downstream GIS tool cleverly analyses elevation data in the web map in order to map a close approximation of the course of the river from its source to mouth.

So the following video clip provides a step-by-step guide demonstrating exactly how to do this.

Let's see how we can use the Trace Downstream analysis tool to map the course of the River Eden.

The first thing we need to do is to find the source of the River Eden, which is just north of Aisgill in Cumbria.

So if we search for that here by typing it into the search bar, and it will take us to Aisgill.

And if we zoom in a little bit, we can start seeing the River Eden just north of Aisgill.

What we need to do is to mark the source of the river by sticking a pin in it.

So we click Add and Create sketch layer.

And you'll see that there are various options here.

The one that we want is the simple vector point.

So if we click that once to say that's what we want do, and then we're going to look for a place.

Now, I happen to know it's quite near to this point here.

It doesn't matter if you're a little bit further upstream or downstream, but if we put that just here, right in the middle of the river, of course, and then what we're going to do is name that so that we don't lose that point.

So we're going to call that River Eden source.

Now, don't click any more points on the map because it'll add other points.

It's quite easy to do that, unfortunately.

But if we just click Layer, we should see the new point just here.

It doesn't give it a name, so we can name it here as well by clicking the three dots, then Rename, and giving exactly the same name as we did before.

We can now let the GIS work its magic by using the analysis tool Trace Downstream.

So having clicked Analysis, we then click Tools.

And in the section Find locations, we click Trace Downstream.

Next, in Input layer, click on River Eden source Points.

Then scroll down to Result layer.

In Output layer name, type River Eden Trace Downstream.

Then click Run.

And the GIS will do its work.

There's a lot of data to process here, so the Trace Downstream can take a little bit of time, but once it's traced it, it shows it as a blue line which approximates to the course of the river.

It's not exact, it's an approximation.

But it's very useful to us, and to actually manually trace the stream would take hours and hours, so it's a very useful thing.

And if we pan out, we can see the whole course of the river from source to mouth.

The mouth of the River Eden is near to Carlisle.

And we can see how it's approximated to the meanders there, but that is fine for our purposes.

We're then gonna save our map by clicking Save, Save as, and in Title, we type River Eden, and then Save.

At the moment, the basemap is the topographic basemap, but we can always change this to something else.

So we go to the Basemap gallery, and we can select, perhaps, Imagery.

And we can see how the river corresponds with that.

And that may or may not improve the visualisation.

You can also change the colour of the layer if you want to.

So the new layer is there.

We can show its properties, and then we can change its colour by clicking on Edit layer style.

And perhaps we might want to choose a brighter blue.

So we click on there, and we can choose that colour blue there.

That's a bit too dark, so maybe we could choose something a bit brighter like that.

And we click Done, and Done again, and save our work.

Then we can hide the Layers panel in the dark toolbar and then pan out to see what the Trace Downstream work has achieved.

We can see a very clear route of the river from source to mouth.

Later, you'll have the opportunity to use the Trace Downstream tool yourself, but let's just check on some points from the video demonstration.

So the first check asks you to select the meaning of the two icons you can see on the right-hand side of this slide.

You may wish to pause the video here while you have a little think about that.

So the correct pair of words to choose here is D, Analysis and Tools.

Well done if you recognised them correctly.

By the way, the hammer icon is used specifically for analysis tools.

For other tools in ArcGIS Online, a spanner icon tends to be used.

This can be a bit confusing until you get used to it.

Now for a second check.

What is visualised by the output line from the Trace Downstream tool? Pause the video if you wish to think about that for a little while.

Well done if you selected B, the course of a river.

Yes, the Trace Downstream tool finds the route taken by the river on its journey from start to finish, from source to mouth.

We're now going to see a second short demonstration in which we find out how to use the Create Watersheds GIS tool to map the drainage basin or catchment of the River Eden.

Create Watersheds is another amazing GIS tool which uses elevation data to visualise the drainage basin or catchment of a river together with its tributaries.

The following video clip provides a step-by-step guide demonstrating how to use this.

We're now going to use the River Eden map to Create Watersheds.

And what that means is we're going to try and map using GIS the drainage basin of the whole of the River Eden.

To make this a little bit easier, I'm gonna go back to the topographic basemap that we used initially because it's slightly easier to see the river.

So we're going to zoom in on the mouth of the River Eden, and we can see the line which is the Trace Downstream showing the approximate course of the river that we created earlier.

And in a similar way to when we were looking for the source of the River Eden, we're now going to do the same sort of thing but for the mouth.

And we're going to add a vector point very carefully to this area here, which is the estuary of the River Eden, just where the river meets the sea, and this bit would be tidal.

So we pin the vector point in the estuary and give the point a name twice, as we did before.

Gonna go to the Layers and name it here.

It comes up as Sketch, but I'm going to rename it and give it the same title in two places.

The GIS can then use this point, this point showing the mouth of the River Eden, and the Create Watershed tool to generate a drainage basin map of the river and its tributaries.

So the next step is to use the analysis tools to get the GIS to work its magic.

So we click Analysis, and we have Trace Downstream is still there, but I'm gonna go back to a different tool this time.

In the Find location section, I want Create Watersheds.

So I click that, and in Input layer, I click that once and refer, this time, to the mouth of the River Eden where it says River Eden mouth Points.

Then I scroll down to the Result layer, and I need to give this a name.

It says Output polygon name.

So I'm gonna type in there this time River Eden drainage base.

It's very important in the title not to include any punctuation.

ArcGIS Online, in this particular section, doesn't like punctuation.

You can always modify the title later.

So now it's time to press the Run button to allow the Create Watersheds tool to do its magic to work out where the drainage basin of the River Eden is.

So it can take a few moments for the GIS to calculate the watershed, and when it's done that, it will appear as a blue shaded polygon by default.

You can change the colour later.

So if we look at the big picture here, we can see how the GIS has picked out that line of high ground around the drainage basin of the River Eden and shown it very clearly.

So let's just save this good work we've done.

And we can also try some different basemaps under this layer.

So we're gonna go back to have a look at the basemap we used before, which was Imagery, and we can see what that looks like.

And that's quite an effective visualisation of the drainage basin using the aerial imagery underneath it.

Having learned how to use GIS to Trace Downstream and Create Watersheds, it might be interesting to compare our work with that of professional GIS experts.

And one of those works for the Rivers Trust that actually have studied the River Eden quite a lot.

So we can look at some of their work.

If we go to Add, Browse layers, and in ArcGIS Online, we search for Eden rivers.

And we can see a layer that's been added by Catherine McIlwraith, and we're gonna add that to our map as well and compare it with ours.

This is a very impressive piece of work, and what we can see that Catherine, who is a GIS professional, has done is to map each one of the rivers in quite a lot of detail, including all the tributaries.

We can see some of them listed just there.

So, it'll be interesting to compare our layer with hers.

And if we go to the Transparency slider, we can do that quite easily by making her layer transparent.

And we can see that actually, our main channel corresponds pretty well with her main channel.

The other thing we could do is compare that, of course, with our drainage basin.

So we can put that on.

And once again, if we just make sure that's on properties for that layer, we can see to what extent that corresponds with that other layer.

And what we can see is actually a pretty good correspondence between the edge of our drainage base, the watershed, and the layers that have been generated professionally.

Very soon, you'll have a chance to use the tools we've seen demonstrated, but let's do one quick check before the tasks.

Is it true or false to say that a suitable output line name for Create Watersheds is "River Eden - drainage basin"? Look at the title carefully.

You may wish to pause the video here and restart it when you've selected your answer.

Okay, this is actually false.

Why would that be the case? You may wish to pause the video again and restart it when you've decided why.

The reason for the statement being false may sound a bit pedantic, but it's important.

Output names for analysis tools really need to be very simple without any punctuation.

For example, "River Eden drainage basin" but no dash.

This is often because the GIS data is underpinned by spreadsheets and coding, which doesn't always cope very well with the way we might write things normally.

However, once created, the names for the results can usually be altered later.

Now for the tasks which will help you to use the GIS tools you've seen in action.

Task 1 is in two parts.

For task 1a, the link provided takes you to the ArcGIS Online Map Viewer where you can use the Trace Downstream tool to map the river's course.

In task 1b, you'll have a chance to use the Create Watersheds tool to map the River's drainage basin.

As a follow-up, task 2 also has two parts where you have the opportunity to compare your work about the River Eden with that of a GIS expert from the Rivers Trust.

So pause the video now to take some time to undertake task 1 and 2.

And when you're ready, press play to obtain some feedback.

See you on the other side of the tasks.

Hopefully you were able to undertake the tasks effectively.

For task 1a, your use of the Trace Downstream tool should visualise the River Eden's course to look something like this.

As optional extras, you may have altered the colour or width of the line showing the river course.

For task 1b, your use of the Create Watersheds tool will hopefully have visualised the River Eden's drainage basin looking something like this.

Again, you can alter the colour fill and outline colours if you wish.

For task 2, you were asked to compare your work about the River Eden with that of a GIS expert from the Rivers Trust.

So for task 2a, you may have something like this on your screen.

Then you can use the Transparency slider to compare their layer with your Trace Downstream and Create Watersheds work.

Then for task 2b, perhaps your conclusions about the comparisons were similar to those of Alex, who found that his Trace Downstream is very similar to the Rivers Trust layer for the River Eden's main channel.

Remember that the Trace Downstream tool is an approximation of the exact course, so if you zoom in, you can see where it cuts corners.

But it takes very little time to create it, whereas to draw an exact course manually might take many hours, if not even days.

Aisha noticed that the Rivers Trust layer showed all of the main tributaries flowing into the River Eden.

Indeed, it is a very detailed visualisation, but we've seen how such work is done.

We could do this too if we had a bit more time.

Then Sofia commented that her drainage basin layer using Create Watersheds goes close to the sources of the tributaries, as she expected it would.

Yes, the correspondence is very good and a useful reminder about what a watershed is, the line of high ground which forms the boundary of a river's drainage basin.

If your answers were very different to these or you recognise some errors, take another look back at the video demonstrations.

Now let's move to our second learning cycle, how can GIS analyse river profiles? Here's a theoretical model of a river's long profile.

You may well have seen something like this in your lessons about rivers or indeed in a textbook.

The vertical axis represents height above sea level, and the horizontal axis represents distance from the source towards the river's mouth where it reaches the sea.

Another very useful tool called Elevation Profile can be used to assess the extent to which a river's profile corresponds to such a theoretical model.

We're going to see a video demonstration of the Elevation Profile tool very soon, but there are a few things to be aware of first.

So far, we've been using 2D web maps, but to visualise the relief of the landscape, we need to use 3D GIS maps.

A particularly good way to do this is to use the ArcGIS Online Scene Viewer, and it shows web maps in three dimensions.

We can also make use of the layers we created in the ArcGIS Online 2D web maps using analysis tools because almost without us realising, they became what are known as Feature Layers.

These are layers which can be loaded into ArcGIS Online in other apps such as the 3D Scene Viewer.

Then we can enhance our understanding of the river landscape by using analysis tools in the Scene Viewer called Scene tools.

You'll be seeing those in the toolbar on the right of the Scene Viewer, including the Elevation Profile tool.

So this is what to look out for.

We find and click the Scene tools spanner icon to reveal the Elevation Profile tool.

Its icon represents mountains or hills with a double arrow to indicate that it visualises changes in height.

So, how can we use GIS, and in particular 3D GIS, to analyse river profiles? The following video demonstration shows how the Elevation Profile GIS tool works to visualise and analyse a river's long profile.

We're going to to use 3D maps to analyse river profiles, and to do that, we need to be logged into ArcGIS Online and then click Scene.

Now, Scene is the 3D mapping facility in ArcGIS Online.

So we're gonna create a new scene, and the first thing we're going to do is to add some layers that we've created already.

So we go to the Layer Manager here and go to Browse layers and check that the dropdown menu says My content.

It'll probably say this already by default.

We can see some layers listed already, but we're going to, just to be on the safe side, we're going to search for the layer name we created earlier, which was River Eden drainage basin, and add it to our map by clicking Add.

And it will appear on the map.

So when you've done that, click Done.

And because this is a 3D map, you can move it around and show the topography quite easily.

We can do that, we can zoom in, we can move the map around like this and look at it in various ways, which is extremely helpful in terms of visualising the landscape.

And you can see there, there is the mouth of the river.

And if we just zoom out a little bit, we can see we're looking from the north now at the catchment, but we're looking at it in three dimensions.

So as we zoom in, we can start seeing quite a lot of detail of the topography.

Our next step is gonna be to add another layer that we created earlier.

So if we just pan out to see the whole of the drainage basin, and we're gonna reorientate the map to the north.

There's a quick way of doing this, incidentally, which is if you just click the compass, it orientates the map so that north is at the top.

That's quite a useful little hack.

And what we want to do is add the course of the river.

So if we once again go to the Browse layers section, and we can use My content 'cause it's a layer we created earlier, I'm gonna type in here River Eden course.

And there we have the River Eden course we created earlier.

So if we just click that, Add, it will put it on the map.

And we can see the line of the river, the course of the main channel, flowing down from the source to the mouth.

And there's the catchment area around it, surrounded, of course, by the watershed, the line of high ground which marks the edge of the drainage basin.

And make sure we click Done.

So having done all that good work, we're going to save this.

And we're saving it the first time as a scene, and we just call it River Eden 3D, or you could call it River Eden 3D Scene, and save it.

And once we've done that, and future saves, any changes we make, we can save in a much simpler way by clicking Save and open and Save once.

Our next step is going to be to use the Elevation Profile analysis tool in Scene.

And this is quite a remarkable tool which captures data that's embedded invisibly in the map, showing loads and loads of data points.

I mean, thousands or hundreds of thousands, possibly millions, each telling us exactly how high a place is above sea level, or indeed below sea level.

So we go to Scene tools, which is in the panel on the right, it's this spanner icon, and we click that once.

And one of the tools is Elevation Profile.

It's this one here.

So if we click that once, we see a panel opens, and actually using it is very, very simple.

I'm gonna move them out just slightly to one side.

What we're gonna do is untick two of the layers, this one and this one, Layers and Line.

We're gonna leave Ground ticked.

And then what we're going to do is select the line or select a transect, and in this case, the transect line is the line of the river, the course of the river that we'd plotted before.

So we're gonna click Select line, and there's a small cross that appears in the cursor.

Don't click it until you're actually on the river.

So when I'm on the river, I'm gonna click it once, and you'll see what happens.

So almost instantly, it creates an Elevation Profile.

And what we can see by moving the cursor is where points are at a certain height.

We can follow the course of the river all the way down its long profile, and you can see the height changing as it gets lower and lower towards the mouth.

So we're now in a position to compare the actual long profile with the theoretical long profile model.

To what extent does the River Eden's long profile correspond to that theoretical model? Well, the overall profile seems to be quite similar to the theoretical model, although it seems a bit steeper in the middle and in the lower course.

Also, the Elevation Profile isn't as smooth as the theoretical model.

There are quite a few bumps and spikes in it.

Perhaps some of those sections are where the river flows over more resistant rock and there's been the development of some rapids.

Sometimes Elevation Profiles can pick up human-made objects, such as bridges or roads.

That could be another reason.

It's also important to realise that the Trace Downstream tool is really good, but it is actually just an approximation.

You could actually make a more accurate Trace Downstream if you followed the river's course and made a hand-drawn course with the GIS.

But that would take a very long time.

So because of the fact that it's an approximation and it slightly cuts corners in the bends of the river, it may be going over little spurs or other pieces of land that jut into the river, and that can create anomalies.

So we need to bear that in mind.

Soon, you'll have a chance to use the Elevation Profile tool just as you saw in the demonstration.

But first, let's check a couple of details.

What type of layer created in a 2D web map can be used in a 3D Scene? You may wish to pause the video here and restart it when you've selected your answer.

Well done if you chose Feature Layers.

These are basically layers of data which have special powers, if you like, because they can be used in other maps and apps.

Now for a second check.

For the icons you can see here in A, B, and C, in Scene Viewer, which icon represents Scene tools where the Elevation Profile tool can be found? Pause the video here if you wish, and restart it when you've selected your answer.

Well done if you selected the spanner icon.

Remember that the hammer icon is used specifically for analysis tools.

That's the icon on the left under A.

For Scene tools in ArcGIS Online, the spanner icon is used.

As I said before, this can be potentially confusing until you get used to it.

Now for the tasks.

For these, you'll need to open your ArcGIS Online account using the link provided, sign in, and open the Scene Viewer.

Task 1 will help you to load your two saved Feature Layers about the River Eden.

That's the River Eden drainage basin, made using Create Watersheds, and the River Eden course, which was made using the Trace Downstream tool.

Then for task 2, you're going to use the Elevation Profile tool to visualise the river's long profile.

Finally, for task 3, you're going to assess the extent to which the River Eden's long profile corresponds to the theoretical long profile model and consider what might cause any anomalies.

So pause the video now, take some time to do the tasks, and when you're ready, press play to obtain some feedback.

Hopefully those tasks went well for you.

For task 1, when you loaded your saved Feature Layers about the River Eden, they should appear like this, with the drainage basin and the river's course.

For task 2, you will hopefully have had the opportunity to use the Elevation Profile tool in order to create a visualisation that looks like this.

Finally, for task 3, your conclusions about the extent of correspondence with the theoretical long profile model may have been similar to Laura's, who found that "the overall Elevation Profile shape is quite close to the theoretical model, but seems a little steeper in the middle and lower course." Good points.

Or perhaps you shared Jun's view that "the Elevation Profile isn't as smooth as the theoretical model of a river's long profile.

Perhaps some rough sections could be rapids?" Yes, that's quite possible.

There are some interesting anomalies, and this is very common when using Elevation Profile to detect long profiles of rivers.

Or maybe you agree with Izzy, who points out that "anomalies may happen because the Trace Downstream tool is an approximation, so it doesn't follow the exact or actual course as precisely as a hand-drawn course." That's a very good point.

Well done, we've covered a wide range of GIS knowledge and skills, and I highly recommend that you return to them and practise so that your GIS capabilities become more fluent.

Let's summarise that learning with these key points.

So we've used three different GIS analysis tools.

First of all, we used the Trace Downstream tool to analyse the course of a river.

We used the Create Watersheds tool to analyse the drainage basin or catchment of a river.

We used the Elevation Profile to assess the extent to which a river's long profile corresponds to a theoretical model of a river's long profile.

So we've found out how to use some very powerful and useful GIS tools in this lesson.

Really well done.

A good way to follow this up is to use those tools again, maybe for a different river.

Why not try them for a river near to your school or home, or a famous river somewhere else? These tools will work in the same way for rivers all over the world.

Hopefully you've found the learning interesting and useful, and I very much look forward to learning with you again in the future.

All the best, and bye for now.