So, in this demonstration we're going to focus on the specialized type of
the spacial modeling.
That's hydrological modeling.
So, this is essentially how surface water is going to run across a particular
topographic surface.
So, if you remember from the lecture that accompanies this demonstration,
there's a basic order to how we do these hydrological models.
Now, essentially we're dividing this up into two big sections.
Both creating a stream network, so analyzing how water would flow across
the entire surface, things like flow direction, accumulation, ordering and
creating stream features, and measuring flow at particular points.
So either looking at the stream networks to analyze how things are gonna flow
across a key location, or creating what we call pour points, and then analyzing how
much of an area is gonna flow out through that particular spot.
So it's actually the water shed that contributes to it.
So the basic order of these is we're gonna start with looking for
sinks in an image, in a DEM.
So areas where water is gonna flow into but not back out.
Then we'll fill them, we'll work with the flow direction and
the field flow accumulation.
We'll turn this into a stream raster by doing a threshold,
we'll calculate the order of streams that are in it.
We'll create a feature layer out of this and
then we'll work with different pour points to calculate watersheds for the area.
So let's go ahead and get started.
You should have in the Demo Data folder essentially just one layer.
This is the same SRTM image that's in the previous demonstration,
in the topography demonstration.
So feel free to reuse it if you don't wanna download it.
There's also one other file in here that's part of an optional assignment that
goes along with this.
This is for each soil class in St.
Joseph County, what we call the E-Risk or the Erosion Risk for it.
So you can play around with that, if you wanted to do the optional assignment, but
once you've gone ahead and downloaded all of your data,
switch back over to ARC DIS and you're simply gonna add in that one layer.
If you need to have a refresher on how to map to a particular folder,
I encourage you to look back at one of the previous demonstrations, but
I'm just gonna go straight into my GIS folder here.
Demo 12, and add in SRTM, so Shuttle Radio Topography Mission Michiana.
This is a DEM or digital elevation model of this region.
Go ahead and hit Add.
You may or may not already have your ArcToolbox up.
If you do, you're ready to go.
If not, you wanna start it off by hitting the ArcToolbox button up here.
So we have a DEM here taken from a satellite, or
taken from a shuttle mission actually.
And what we wanna do is do all these hydrological tools on it, and
the base data for most hydrology in a JANUS context for
surface hydrology, is a digital elevation model.
You can start with a ten and then convert it into a DEM, but
you really need that grid based system to accurately do a lot of these measurements.
So the first thing that we want to do is go into our spatial analyst tools.
And almost everything we deal with in this demonstration is gonna be in
Spatial Analyst.
And then almost all the tools we're gonna work with are in the Hydrology section of
the Spatial Analyst Tools.
The very first thing we wanna do is let's just assess whether or not we have a good.
DEM, to serve as a base mount, or as a base layer.
So we're gonna start off by creating a flow direction here, so go ahead and
click on flow direction.
It's gonna ask you for your surface rastor, that'll be that SRTM.
And it's just gonna only then ask you for the output flow direction.
All it needs to calculate this is the input surface.
So let's go ahead and give this something permanent.
I'm gonna put it in my Demo 12 folder.
But I'm gonna call it Michiana flow direction raw.
I raw, this is a little bit of a spoiler but
we're gonna work with one that we've done a fill on afterwords.
This is just differentiated from the floor direction that we're gonna run
a little bit later.
Make sure you hit the dot tif on there.
It will give you an error because the file names too long for
the type of system that it defaults too.
So choose your tif, hit save and go ahead and run it.
So, when this comes up, it's gonna be coded for
us in sort of an eight bit way to powers of two.
It shows us what the direction is.
So a one is going be straight to the east, a 2 is going to be to the south east,
a 4 is going to be to the south and an 8 is going it'll be to the south west, 16 is
going to be to the west, 32 is the north west, 64 is north, and 128 is north-east.
I don't expect you to remember those because they are in the slides and
they are actually in the demonstration notes as well.
So, if you remember from the lecture, one of the things that we
talked about with these images is that if it can't figure it out,
if there's a sink in the image, if water flows into one spot or
if it's ambiguous about how it would flow back out.
It's going to give it the sum of all of the different values that it
could possibly be.
So that's why we end up with things like 255, so we're scaled from 1 to 255.
Most of the values in here are probably going to be 1, 2, 4, 8, 16, 32, 64, 128,
but in any case it doesn't know what to do, it's gonna put them in there.
So, if you have values other than those sort of set eight values that give you
directions, what you want to do is run the sync tool
to see where those areas are that are a little bit ambiguous.
So, let's go ahead and run sync now.
So, the sync is just going to ask us for the flow direction raster so
go ahead and rag that over.
And I'm going to call it Michiana_Sinks.
.tif.
So, when you run this it's going to look at the flow direction or ester and it's
going to find all the ambiguous areas and flag them a little bit differently for us.
So it'll come up, and
you can see that there's actually 12,000 spots in here that have some ambiguity.
You can only really see this if we start turning off the other layers.
And what you see is, in some cases, these are lakes.
This is the lake in Potato Creek State Park.
Some of these other ones are actual lakes in the image.
However, a lot of the other ones are just spots where that particular pixel was
coded slightly below, elevation wise the ones around it.
Our two here are essentially exactly the same,
we don't know how water would flow across them.
We have some peaks probably in there as well.
So So what we wanna do to process something like this is we want to
fill them, even in cases where we know that water actually flows in, and
maybe doesn't flow out for a while.
It eventually does flow back out, or
would if enough water got into it, but so it's a valuable thing for
us to be able to understand how the hydrological across the entire surface is.
Whether or not it's truly, truly accurate, and whether water would sort of- whether
there would be a reservoir of water there, or not.
So, the next thing we want to do is run the fill tool,
so we can get a syncless DEM sinkless topographic
surface to then use for all of the further analysis.
So we're gonna run Fill next.
In this case it's gonna ask us for the input surface raster.
Always be very careful that you're looking for what it's asking for in there.
In some cases, tools that you might expect could work off of the DEM will
actually want the flow direction and vise versa.
So, in this case, it wants the surface, so bring that in
Michiana_DEM_Filled.
So I'm gonna change the name just a little bit.
And hopefully be able to spell.
.tif.
So now when I hit OK, it's gonna run for a moment.
And when it comes back up, we're gonna have something that looks
pretty similar to the DEM that we had in originally.
So I'm just gonna turn off all the other layers, put that original DEM.
You'll notice that the values are slightly different, so
that the very low pixels have been raised up a little bit.
And I'm going to change the color ramps just by clicking on the color ramp there
to be that standard elevation one there just, so
we can see the differences between them a little bit more clearly.
So, I can go ahead and turn one off and turn one back on.
You can see some of what's happened in there.
So areas that were previously, I'm just gonna zoom in a little bit on one here.
Areas that were previously very low but surrounded by higher topography,
have been filled up to a level where the water's gonna flow back out of them.
So it's assuming that there's quite a bit of water to give us a model of the entire
surface here.
So from here on out, this is the one we want to be working with.
We're gonna reroute a lot of these tools,
with this filled in DEM is gonna give us a complete hydrologic model.
So I'm gonna turn everything else off.
If you wanted to, you could remove them, just so they're not confusing,
as long as you've saved them permanently for any sort of assessment.
So since we've run the fill tool, the next thing we want to do is
rerun Flow Direction to give ourselves an accurate measurement of it.
So go ahead an choose Flow Direction.
And we're gonna use this with the defill DEM.
Ignore the drop raster, ignore all the other things up there.
And I'm gonna call it Michiana Flow Direction Filled.
So, just choose the old one and just change what's in there.
Dot TIF.
So I'm gonna zoom back out to the full image so we can see this.
And when it's finished running what we'll end up with is
something where there is no more ambiguity in there, so
it contrasts to the photo direction where we had anything from one to 255 in there.
In this case we only half those actual directions.
So one, two, four are powers of two
from sort of East to all the way back around coded for direction.
So we have an accurate measure of how water is going to flow across
any given area on there.
If you remember from the lecture from the way that we did this before,
the way that we did it in sort of the demonstration lecture part
the next thing to do is flow accumulation.
So we want to see how much water is going to build up in particular
places as it flows across the surface.
So we're gonna choose the flow accumulation tool here and run that.
In this case it wants our flow direction raster.
Just make sure you're giving it flow direction filled.
We're not gonna worry about the rest of the things other than setting the output
to be Michiana flow accumulation.
So I'm just choosing old ones so I have to minimize my typing since apparently I
can't spell or type anything today.
I'm gonna call it FlowwAcc.tif.
And hit OK.
So what it's going to give us is a measurement of how much water, or
how many pixels are going to collect in particular spots.
So, we'd go from things where that pixel, nothing else flows into it, so
zeros all the way up to some spot probably on the edge of the image Where 350,000,
almost 360,000 other pixels flow through that one place.
So that's an area where there's likely to be a lot of different flow there.
So if we wanna see it a little bit more clearly, we can go into the layer
properties for it over to Symbology.
And it's gone ahead and
put a stretch on it just like any raster image that comes into our GIS.
Let's go ahead and just change it a little so
we end up with a standard deviation stretch of .25.
This will make everything a lot clearer in there.
So, we can sort of see the network of things that it's starting to put in.
So what we wanna do to go any further with this, so
we wanna create what we call a stream raster.
And to do a stream raster, this is one where there's not a tool over here for it.
We want to threshold this image, so we want to say,
okay we're not worried about those places where only 50 other pixels flow into them.
We're really worried about the bigger ones.
Those are what's interesting to us.
So that's what we actually want to measure.
And this will make it so that there's a lot less data for the computer to process.
It'll make things work faster, and give us a better view of the actually important
hydrologic channels, and water flow channels across this area.
So theres two different ways that we can do this, one of which we've already
worked with before, that's using the reclassified tool.
And the other is using what we call a Con tool.
And this will go through and
basically if it's one value it will give it one thing, if it's
the other value it will give it somebody else's conditional is what it's doing.
So either one is equivalent.
I'm gonna show you how to do both of them.
Don't feel like you need to do both if one works okay for you.
So the first part, just doing a reclassification here.
I'm sorry.
In Reclass, Spatial Analyst Tools, Reclass, Reclassify.
We're going to bring over flow accumulation three classfield as value,
choose classify we're going to give it two classes, and
the break value in there is going to be 50 So less than 50 pixels one thing happens.
More than 50 pixels another thing happens.
What we want this to be is actually if it's zero to 50 we want
to give this no data.
We want to make this so it just gets tossed straight out of there.
So we'll just choose n.
Lowercase o, no space, capital Data, just like the one that's down here.
And if we wanna add in the other class, we're gonna give it a 1.
Let's go ahead and give it a permanent output.
Gonna call it Oceana_streamRaster01.tif.
01 is only because I'm gonna do it twice.
You don't probably need that.
Hit save, and OK.
Before I go any further, just in case you start getting weird ghost values just like
we did in the past, remember that when it calculates these values that it's gonna
look at, it's maybe not looking at every single pixel in the image.
It's taking 50, 25% of them and
assuming that it's gotten whatever the variability is.
If you end up with weird, high ghost values still in there, you can always go
into classify here and just change this maximum value to be a little bit bigger.
So Maybe instead of 35 over here, I'll just change it to be 37.
So that's not actually changing anything that's in the image.
It's not even changing anything that's in the classification, although it did sort
of take away my prebuilt values here that I just have to reenter no data.
One.
But what it is going to do is it'll catch any sort of
ghost additional values that are in there.
So go ahead and hit OK.
It should run for just a moment, going through and looking at every pixel.
If it's less than 50, it gets no data.
If it's greater than 50, it gets 1 and
it'll create just those stream channels for us.
It's not gonna look like much happens until I turn off everything else.
And you can sort of see that it's just thrown out all the values and
given anything greater than that of one.
But we do this so that we can then rank the values that are in
there based on how many channels are sort of flowing together.
The other way that we can do this, just to step back for a second, the other way we
can calculate a stream raster is to use that con tool that I was talking about.
This is, perhaps, a little bit faster.
We could either use the conditional tool that's up in here, or
we can also simply do it in the Raster calculator.
I'm just going to do it right in the Raster calculator real quick.
So you bring in your image, you load up the Raster Calculator, and
all you want to do is hit Con over here Michiana Flow Accumulation.
For the comma there, you want to use greater than 50.
After the comma give it a 0.
So it's basically saying if it's greater than 15, or sorry give it a 1,
if it's greater than 15 make that value 1.
If anything else, just ignore it.
Just throw that pixel right out.
Give it no data.
So it's a faster way to do this analysis.
Let's give it an output name I'm just gonna call mine streammaster2.
And they should be identical because the underlying math that's
going on is exactly the same.
So they just come in as different colors, but
you can see that they are identical images.
So, once we've created this raster of all of the stream channels that
are interesting to us, the next thing to do is to order them.
To create something that ranks them based on how many other channels
are flowing into them.
We're going to do this back in our hydrology tools.
So in my toolbox, I'm in spatial analyst again.
I'm going back in to hydrology, and what I'm gonna choose is stream order here.
So in stream order, it's gonna ask me for my stream raster.
This is either one, you should hopefully just have one,
if you followed along with everything you have two.
If they're identical, it shouldn't be a problem.
It wants that.
And it wants my flow direction to come in.
Now in the lecture part of this I talked about the two different methods,
Strahler and Strive.
Just leave it on Strahler.
They're really kind of equivalent data.
They're just different ways of ranking them.
And I'm going to go ahead and spit it out as miscellaneous stream order,
.tif.
And go ahead and hit OK.
So this will run for a moment and
it should come up with something that's ranked for
us and that's exactly what's happening here.
So it's ranked them based on the number of other channels that are flowing into them.
If for some reason your's comes up, if you're using an older version of there is
a glitch in the program where this might come up as nothing but one's, so
it'd look almost identical to the stream raster here.
If that happens when you do it, don't specify the output raster.
Let it go to that default one that it has there.
It will come out properly and then you can just simply export a new copy of it or
work with it from that temporary location.
It was just a weird little problem with some of the earlier versions
of the software.
So, once we have our ordered, ranked things here,
the next easiest thing to do is to turn this into a vector file.
So, what we have here is lots and lots of areas that are not actually anything
important, and bigger ones that sort of feed into each other and are very linear.
So we wanna convert these into a feature polyline shape file.
So we do that with Stream to Feature here.
So we choose Stream to Feature.
Input your stream raster.
In this case, it's the ordered one.
Input your flow direction raster.
You can leave it on simplify poly lines, that's fine.
And we're gonna spit it out as Michiana Drainage Paths.
You can put .shp if you want.
Don't put .tif because this is a vector layer.
It'll default to it as well if you leave it blank.
Just go ahead and hit, OK.
And now what we should end up with is a vectorized version of this that maintains
the ranks that are in there.
So it's not gonna be immediately apparent
until I turn off some of the other layers that are in here.
I'm gonna go into my layer properties for Michiana drainage paths.
Either by double-clicking or right-clicking and choosing Properties.
I'm gonna go over to Symbology, I'm going to choose quantities,
graduated symbols, and go to grid code.
So, grid code here is whatever was coded into the raster that was there.
It'll yell at you about the maximum sample size, that's fine.
It just means that there are lots and lots of little poly line segments in here.
And since there's six different values possible,
I'm just gonna change my natural breaks to be 6, so it'll do this for me.
In this case I think it's probably good to change my template so
that my water is blue.
So I'm gonna do that.
So it'll change the color without changing anything else about them.
Hit OK.
So it accidentally zoomed in a little bit there.
But what you quickly notice.
Is it the very big channels?
This is the Saint Joseph River so it's not a surprise.
This is just a big channel, sort of leading off another part of the area.
Some of the other ones flowing out to the edges are the larger ones.
So one, a couple things you may notice on here.
If you see spots like this right here where lots and
lots of things are happening linearly.
And flowing almost exactly the same direction.
That's usually an indication that there's a lake or something there and
the sink has filled.
Filling the sinks is filled with all to the same layer.
So it can't really resolve that it flows together.
Those are just little artifacts that show up, they don't mean anything.
But your eye will start catching them and making you realize that that probably
means there's something quite flat right there.
So now that we've done this,
we've created sort of how water's gonna flow across the entire surface,
where it's likely to collect, where it's likely to sort of build up.
And the next step, or the next stage,
is to look at the drainages of individual points.
So there's a few different tools we're gonna work on in here.
I've just zoomed back all the way out.
I'm gonna go ahead and turn off my drainage paths for
the moment just because it takes a little while to render all of those lines.
But I am gonna turn on my fill DEM just so I have an idea of the area I'm looking at.
So the first thing I want to do is look at the flow length.
So essentially the flow length is how far each pixel of the DEM, it's gonna
flow before it leaves the edge, before it reaches the edge of the data that we have.
So go ahead and choose flow length.
You wanna bring in your floater action.
So I'm just gonna minimize some things over here so
that I can see everything I want, so floater action.
And I'm gonna call it Michiana flow length.
That TIF this is a raster that it's outputting.
And what its gonna show me is for
each pixel how far it has to travel before it leaves the edge.
So this would be quite useful if you wanted to say, have a correlate for
how long somethings gonna stay in the area,
if there's a spill in a particular spot how long it's likely to stick around.
And this becomes very apparent what's going on if you turn on the drainage
paths as well.
So you see that stuff over here has to flow all the way down here, all the way
back into the main channel, and then all the way back off before it leaves.
So these are why some of the very very long ones is they have to
flow quite a long distance before they get out of the image itself.
Whereas stuff over here just has to flow down a little bit so
it has a much lower value.
So this is just a simple little analysis that
you can run to get some idea of how long water is going to stick around.
Obviously if you had a bigger DEM, if you had a bigger extent for
the DEM it might be different.
They might even be relatively different and absolutely different.
So the size of your DEM does initially control quite
a bit of what's happening here.
So I'm going to turn drainage paths off again.
And the other tool I want to run in here is what's called basin.
So we've talked a little about watershed.
So the area, the catchment of a particular point.
What the Basin tool does is it runs this for the entire area, so
it's gonna divide the entire area up into
different basins based on sort of where they pour out of the edge of the image.
So it's similar to the flow length but it's gonna be a little but
more of a categorical way of looking at it.
So choose basin, all at once is our flow direction,
make sure it's the flow direction filled.
And I'm gonna call it Michiana Basins, and
again I just chose another one there to then change the name.
So it'll run for a moment.
And it'll divide up the entire area into basins.
The vast majority of them are going to be very,
very small little ones around the edges.
There's 1600 in here,
some off them are enormous like these big black ones here and the ones down here.
But the majority of them are little, little,
tiny things where there's one little section that only flows off the edge.
You could do some sort of classification of these based on their size.
If we open the attribute table for that roster,
you'll see how many pixels are in there for each one.
So it would be fair to say that anything with a one,
probably less than a ten is not really important.
But some of the really big ones have many, many,
many pixels that are flowing, that are sort of classified as the same thing.
So I'm just turning these off so I can see everything beneath it.
And, as I just said, the Basins works off of doing it for the entire area.
But what's often more interesting is to, say for Notre Dame campus,
to find out how water is likely to flow across a particular intersection.
Or across a particular site, or through someone's yard.
And that's where we bring in what we call pour points.
So, pour points are an area where we can classify the size that's flowing through
that particular spot, the catchment of water that's flowing through there,
the watershed of that particular point.
So, were going to do that by first creating points to, sort of,
measure this off of.
So, the first thing we have to do is create a new shape file.
This should be familiar if you've worked through the demonstration
where we worked on vectored data and creating new vector data.
But if you haven't, you go over to the catalog tab, it should be on the right.
If it's not visible, you can probably get to it through windows catalog as well.
Find your folder in Folder Connections.
Right-click on the folder that you want to build this into.
So I'm gonna right-click on Demo 12.
I'm gonna choose New shape file.
Then I'm gonna call it pour points.
I don't need to put the .shp on there, but you could if you wanted to.
It is a point-shaped file.
The coordinate system, I wanna go ahead and specify.
It's gonna be our usual one.
If you followed along in a previous one,
it might show up in your favorites up here.
If not, it's projected.
UTM, WGS 1984, Northern Hemisphere, zone 16 North.
I do just want to specify one more time that this is the UTM zone for
Indiana and a good chunk of the mid-west.
If you're working on data from elsewhere, you're going to need to know your own
UTM zone, and not necessarily use this individual one.
Hit Ok and then Ok.
What we now have is a new shaped file to begin working with.
So before we do anything else with it let's go ahead and right click on it.
We're going to go to edit and start editing.
So now we're ready to begin building new points in here.
If your create new feature tool did not immediately pop up the way mine didn't,
it's right on the end here, just choose that, four points.
Make sure it says points.
So you might be starting to run out of space on here.
But we're just gonna put them randomly kind of across here.
One thing I want to be very clear that you're not doing,
cause it'll make a difference later on.
Is don't have the drainage paths on.
If you have the drainage paths on it's going to snap directly to them.
Kind of defeats the purpose of doing the next thing we're going to do.
So make sure that they're off.
And then I want to try to just see what the catchment is.
What the area flowing through some particular spots on here are.
So I'm going to put about ten points on here.
I'm going to put one down here, put one over here.
And then just a few others that aren't really in the middle of big areas.
Try to catch whatever's flowing down from the top there.
So I think that was around ten or so.
Before you stop editing, just so the computer knows the difference between
these, go ahead and open up the attribute table for it.
Right click on it in the table of contents, this ID field over here.
Just go through and change the numbers.
I'm going to do one through ten one through eleven,
rather, you're welcome to do different numbers in there if you want.
Once you've done that, this just gives them individual IDs you can use.
Make sure you clear any selections going on.
Go to editor, stop editing, and say yes to saving your edits.
So you've now created a new Pour Point Shapefile.
We're going to be able to see what the catchment is for
each one of those points, by using the watershed tool right here.
So the first thing it wants is the flow direction.
Michaina flow direction filled.
The next thing it wants is the Raster or feature PourPoint data.
So what we just created.
Ours are features right now, so bring that over.
It's gonna ask you what the PourPoint ID field is.
In this case it's ID.
But I'm gonna give it an output as.
Michiana Watersheds Raw.tif.
Now the "raw", again,
should give you an indication that we're going to do this a second time.
So go ahead and hit save and OK.
And it's going to calculate how much of an area is going to flow out through each
one of these points.
And it's gonna give us a new image that probably,
doesn't look like particularly much.
Largely, because I'm not super good at clicking the one little pixel
that lots of water is gonna flow through.
So it probably looks like very little happened.
If we zoom in enough, we'll see that there's a tiny, tiny,
tiny little watershed associated with .2 there.
And it should be with each and everyone of them.
In this case, I did a little bit better.
I got maybe the area where 15 to 20 pixels is gonna flow back out of.
You may have done a little better.
If you have enormous ones on their,
you probably still had the drainage passed on this snap directly to them.
But if you didn't, then you should have something that looks kind of, generally,
like mine does here, where there's not a lot of area being caught by them.
Now, this is probably a very good measurement because the way that it works
is, water's gonna flow through one pixel and one pixel only as it accumulates.
Now realistically, if you're a little bit close to that pixel, if you're five or
six pixels on either side of it,
you're probably gonna have a lot of water flowing across here as well.
So what we want to do to give a slightly better measurement is to move these pour
points so that they're in kind of the maximum flow accumulation for an area.
This will give us a much better indication of what the drainage through that spot is.
So this tool that we're gonna run on our original pour point, point shape file
there, is snapped four point, so go ahead and double click on that.
Bring over pour points.
The ID field should be exactly the same.
The input accumulation raster is what we wanna work with.
So that's going to be Michiana flow accumulation.
I'm going to go ahead and
make the snap distance, this is a 30 meter resolution DEM.
So, I'm going to go ahead and say as long you're within ten pixels
of that spot, that's probably good.
So, this is going to be a little bit of a,
you want to decide what you want to do here.
This is 300 meters, that's a pretty big flow direction,
our radiance, radius to have around our snap.
So if you're using a smaller region, you may want to make it 100.
You may even want to make it smaller than that.
But don't make it zero because it won't move anything at all.
So I'm gonna give it an output as snapped 4 points,
.tif, and hit save.
Then when I run this,
I'm gonna end up with something that's a little bit different.
I'm gonna end up with essentially, a raster version of a point shape file.
That is in now way what that's supposed to look like.
So this is, you remember,
I talked a little bit before about an error that's in there.
I'm gonna go ahead and remove this.
Because what this has done is incorrect.
I'm gonna rerun my snap pour points tool.
I'm gonna bring over my point feature data.
I'm gonna bring over my flow accumulation.
And what I wanna do here is I'm just gonna leave it as the default name here.
I'm not gonna change anything there.
I'm gonna put it at 300.
What this does is it sends it to that temporary location.
That temporary location's a little bit more
forgiving about some of the glitches that happen.
So just run it like this.
Hit okay.
If you really wanna save those snapped four points you can
by right clicking over here.
This is the new layer that just came up.
Choosing data, export data.
We're going to specify the folder first, so I'm going to find my demo 12 folder,
right here in the location and then the name I'm gonna give it is gonna be
what I said before, snapped or point.tiff.
So I encourage you to save this thing permanently but
it will probably give you that same thing,
where you have those little windows and that kind of really weird looking layer.
So hit save.
I'm overriding one because I already created one that didn't work.
So I'm gonna say yes, it's fine with me to overwrite that error, erroneous one.
And to add it in, that's fine as well.
So I'm gonna remove that temporary one, right click remove it.
Now, what this will look like, I'm going to turn off my watersheds over here.
But if I zoom in on my points here.
You see that I have a point right there.
And one pixel over here.
It's within that ten pixel radius.
This is where it's moved into.
This is the area within there with the highest flow accumulation.
And it should be that way for every one of them.
So if I go look over here, you can see it's moved it over there.
So 300 was a pretty high difference.
Realistically, you may wanna do a little bit less.
All right, so now what I wanna do is rerun the Watershed Tool and
it'll give me a better idea of how good those were.
So I'm gonna rerun watershed again, it wants my flow direction.
So that's gonna be Michiana flow direction field.
It wants my raster or feature pour point data.
Well, now I have raster pour point data and it's snapped pour points.
Value field is value, I'm gonna call it Michiana watersheds.
Snapped.
[SOUND] Hit save.
Hit OK, and now when this runs it's going to give me much much bigger water sheds.
Because it's moved it within that radius to a better point.
And I should end up with something that's a little bit more representative of
how water is gonna flow across the entire surface.
And then how it's going to leave through those points.
So that one that I did that's in the middle of the St. Joseph River there.
It's actually catching everything that's upstream of it now.
Whoops, I zoomed in on tha.
I'm sorry.
The same thing is true for some of these other squares.
It's catching quite a bit of water that's flowing out.
The sort of higher slopes over here.
And the same over here.
And these are more indicative of how water is actually going to flow
across the surface.
So that is that is
most of the demonstration on using the hydrology tools.
We've gone thrown almost all the ones that are in there.
Then this is how you would work through hydrology, getting several different
layers that might be useful to use elsewhere in a model.
I encourage you to let me know if you have any questions,
please do follow along with the assignment.
Thank you and have a good day.