Delineating Watersheds in ArcGIS Pro

hey there this is still white the earth sciences librarian see Boulder just making a follow-up video from a previous video about delineating drainage basins this one is about going a little more specific into delineating a watershed in this case we're looking at the watershed that is associated that data flows into this what appears to be a dam or hydroelectric plant or something like that okay so have a couple of tems loaded here and these basically cover whole catchment area what we want to do first is merge these together so I'm going to go to the analysis tab and open up my toolbox so in our tool set the tool we want to use here is found under data management tools and then you want to go down and select raster then it's under raster data set mosaic - new raster our input rosters are the two masters we have here I'm going to set your output folder I'm working gonna put mine store mine with some of my other data okay and give it a name call it merged TM requires an extension and these are dot tips as we can see over here so it's gonna be done yeah spatial reference is going to be the same as both of these inputs they're both in wgs84 the pixel type you can right-click on the raster and go to properties and then arrestor source raster information you can see that we are working with 16-bit so go back to our tools will go at 16-bit unsigned and will be the rest the false and ready Oh number of bands is also required that's a DM so it's of one and go ahead right okay so now we have a merged raster the stretch values are the same everything looks clean so at this point it will be helpful to clip this down running some of these geoprocessing tools over this large raster will take time so it's it's a good idea to kind of clip it down at this point here's kind of our area since it's a dam we mostly know that it's gonna be flowing and kind of in this area into the catchment we want to make sure we catch it all so I don't want to clip too much off so I'm just gonna use the extend of the window to clip it so the kind of easiest way to clip this down in my opinion is just to go over to your layer right click on it go to data export raster and your output raster we can we can name it clipped clip we'll call it clip diem and for clipping geometry you can go to current display extent to cut it down and go ahead and export that okay that's done so now we have left it's just this area which hopefully covers the entirety of our of our drainage basin of our watershed the dozen you might have to do it again and to make sure you get the whole area but we're gonna go with this I can remove these at this stage so okay we have our lair that we're gonna do our work from and so first thing we want to do is go back to our geoprocessing tools close these out we're done with this set of tools for now we're gonna use the spatial analyst tools so drop that down and specifically ever going into the hydrology toolset and the first thing we want to run is the fill tool which basically just smoothes it out to make sure there aren't any sink points or errors in the DDM this and we're going to use our clip TM we can name our output diem something like diem filled run it this one takes a minute to run okay that's done and for me it took 30 seconds so the next tool we're gonna run is the flow Direction tool and the input is going to be our fill DM and call the outputs flow direction okay what we have here is a DM actually just it's more of a model that essentially looks at each pixel and assigns a value to it based on the direction of the cell that is adjacent to it that is the steepest drop so next another one we want to run to flow accumulation tool it's also right here in the hydrologic tools the input is going to be the flow Direction raster that we just created output you can call it accumulation run it this one also can take a little bit of time to run okay bloke emulation tools finally completed it took five minutes on my computer so this is all done and what we have here is basically a binary image that outlines based on the DM what the hydrology network should look like you zoom in you can kind of see it there's a stream here this little step is important so we want to find our site again which is right here zoom in on it and I am going to turn my flow accumulation layer back on and go up to appearance and we're gonna make a kind of transparent here so we can see through it so what we need to do now is select a pour point pour point is basically the out the output of the entire drainage basin of the entire watershed which in this case this dam will be you know along this streamline that's close to the dams we can get it so what we need to do is create a new polygon sorry not polygon a new vector point layer so I'm going to go over to my catalog and under folders our project folder watershed delineation is when I named my project there is a default geodatabase here and I drop this down I can right-click and go up to new and create a new feature class future class name what's called a 4-point geometry track type is going to be point the coordinate system we want to use prefer to use the same thing as a whole my other stuff which is wgs84 everything else is fine click run okay so now we have over here in our table of contents a pour point if I were to look at the attributes of this we'd see that it's empty there is nothing yet so what we need to do is create that pour point and essentially we're gonna place it as precisely as we can onto one of the cells that represents the streamflow Network so I'm gonna go with point select to go up to edit and click the create button and select a pour point and then we're just going to drop it in right here on this cell that represents the stream network if we if we miss the cell and put it over here we could kind of mess up the the the model ever creating so we want it on this and when that is done we've got it on there and click Save say well let it's yes okay clear my selection okay now we have our pour point the outlet point for the entire watershed at this point we don't need flow accumulation anymore we've got our flow direction you zoom out okay so now is the final step so back to geoprocessing this time under hydrology we're going to run the watershed tool input is going to be the da flow direction raster which is the flow direction raster we created earlier we named it flow direction input raster or feature pore point data so you could input a raster or you can input the point feature we just created we're going to do that we can leave the four point field IDs just object ID that's fine and then we're gonna just name our outputs watershed and click run okay so now we have our watershed delineate it great what we can do now is convert this to a vector we go to do processing done with our hydrology tools we're done with everything in spatial analyst we can go up to conversion tools and under from raster we can choose raster to polygons and our input raster will be watershed and we can make our output raster we call it watershed boundary run okay I'm gonna turn some of these other layers off now let me don't need and we can change our symbology here by clicking on the symbol and the table of contents and and the properties give it outline color of I don't know red and a clear so apply and great and we've do we need in our watershed and created effective polygons out of it so that's essentially how it works and as I was doing this I followed these directions which I'll link in the in the description of this video these are just as arees kind of detailed directions on how to create a watershed model using the hydrology toolset we added on the front in there how to merge two dm's in arcgis pro and that's wrap on this video so definitely let me know if you have any questions you can you can hit me up at philip white and colorado edu bye for now

Channel: Philip White

Views: 8,639

Rating: 4.9661016 out of 5

Keywords: GIS

Id: WCeAM5sYMU0

Length: 14min 34sec (874 seconds)

Published: Thu Jan 24 2019