ArcMap 10.2: Hydrology analysis using ArcGIS

oh yeah thank you for joining me I'm just going to make a quick short video about digital elevation models within this video I'm hoping that we're going to learn how to hydrologically correct a digital elevation model and derive some hydrological data sets like flow accumulation flow directions and some stream networks so this is a digital elevation model has been freely available it's a 90 meter resolution and you could get it from srtm website but it's a important to keep in mind that sometimes when you download this data they come up with some errors or some problems if I may say most of the way there we are digital Bayesian models is some artifacts and you tend to get some sinks which they aren't really sinks actually they just the some errors the might of a cord during the collection or maybe the interpolation technique that's been used for the creation elevation model so what we are going to do first is to hydrologically correct the data set make sure you do have your spatial analyst toolbox turned on you can do that from the customize extensions and make sure it's turned on here I do have my intern on and I'm just going to use the search bar it's very much quicker for me to use so it's just going to type in here and here we go we have the feel from this budget under this toolbox and what you need to do is to drag in the digital dish model and put it in and I'm just going to let go to the default geodatabase and I'm going to rename it to D and underscore field and every other thing is going to be left as default and that's clicking ok and it's completed if we just quickly visualize this two different elevation models we don't really see that much of a difference because it's not really meant to make any much difference what it really does is just correct the DM if there are any sinks which aren't really sinks it tends to fill it all and your digital vision models rates go and the next one's only use is the L direction I'm just going to type in flow direction there we go and you bring it the flow direction what this tool does it takes the digital vision model and create a new raster model of flow direction of the directions that water flow to on the surface of your DM so I'm going to put in the digital vision model let go to default geodatabase I'm going to rename that to the M underscore FD for flow direction the baby items default click okay and hopefully that shouldn't take that long get 2.6 seconds and here we're going to have a new raster datasets they've been color coded for us already and it does have this number that's been classified 1 2 4 8 16 32 all of this number means different directions of the flow if you go into the flow Direction 2 and you go into to health you will see a better description of what this numbers means they all means different directions some are going to do not so I'm going to the west and to the south with this model you can be able to determine stuffs like the surface runoff within your study area and other things like that and the next tool I want to uses of flow accumulation here we go what the flocculation does is it takes the flow Direction roster and it calculates the pixels that do have the highest number pixels that flowing into it so it could actually just calculate basically the areas or the pixels with the highest amount of water accumulating within that area I'll let it go to the default geodatabase rename it DM underscore FA for fill accumulation lift out the type of floating point and run hopefully this shouldn't take long four seconds good and here we go and what the highest number here twelves was sixty thousand eight hundred thirteen it means this area the the white areas basically other areas with the highest amount of accumulating water within the study area and what I want to do here is create a stream network from this flow accumulation raster dataset and one way of doing it is to play around with the symbology in the classification techniques so why I did was just this area too fast i double clicked on the digital vision model or the flow accumulation i just created and it invoked up this layer properties window and i go on to the symbology tab and go to classified and going to classify and take the classes down to two and what I do is I start playing with this number from let's say 1000 and see what it looks like I'll take 31,000 to be not a in relevant in terms of stream networks and whatever starts from 1000 to the highest number I want to see it as a stream network and here we go this is what I do have so all this pixel the pixels ranging from 1,000 to 60,000 1813 and I want to consider this as my stream network within my study area but the thing here is I do not have this as a permanent layer and only with let's find a flocculation Western so what I want to do now is to use the raster calculator to help us create a new boolean raster model of a stream network so what I'm going to do is that I'm going to use a conditional to what I like doing here in the raster interface is to just punch into the to the keys into the layers rather than typing it in because it's a very sensitive tool here we do have so I'm going to make a conditional statement I'm going to say please GIS give me all the floor attenuation pixels the greater equal to 1000 if this is true give me back one and if it's false I don't want to know about it so just give me no data and I'm going to let it go through the default geodatabase I'm just going to rename it a strain underscore net keep it short and click on OK and hopefully this will give me a new raster data set with just the stream network so now I do have mic like a malaysian rest of my flow direction raster or hydrologically correct digital elevation model which i use the field so on and finally now i have created a stream network layer so thank you very much for watching if you do like this video this like below

Channel: Usman Buhari

Views: 48,035

Rating: 4.9304347 out of 5

Keywords: GIS, Hydrology (Field Of Study), ArcMap (Software), ArcGIS

Id: 8XEVDhpGfD8

Length: 7min 45sec (465 seconds)

Published: Fri Aug 29 2014