Latest Contributions by MarkBoucher

Jan, My guess is that there is a road or railroad embankment that crosses your expected flow path (I can see it in your first image) and that the DEM is filled up there and doesn't "know" there is a culvert/bridge to for flows to go in that direction. When you fill you fill up to the lowest point on that embankment and the fill function does its job. To get around this, add a line layer and draw a line where the culver/bridge is. The create a raster (DEMLine) using line(s) with the cell size, etc. of  the original DEM. Where the line is you should have 1 and where it is not 0. Then multiply DEMLine by some big number (say 500). Now DEMLine from your original DEM  and you make DEM2. This step "burns" a hole in the DEM where the culvert/bridge is.  Run the fill tool and flow direction tool starting with  DEM2.  The fill step will fill up the "hole" where the culvert/bridge is created but only as high as the DEM is on the low side. You get DEM3. The flow direction should be as you expect it to be   The Arc Hydro add on is made for this. I created this thread (https://community.esri.com/t5/water-resources-questions/archydro-problem-solvers/m-p/1246227#M4287) focused and sharing my journey with Arc Hydro. In Arc Hydro the above layers have some default names. I believe they are (it's been an while...) DEM = rawdem line layer = agreestream DEM3 = agreedem (this is a "hydraulically correct DEM) Good luck, Mark ... View more

C, I'll share the file Target Locations and file structure on one of mine. Maybe a picture will "paint a thousand words". My project folder is "ArcHydro" and my .mxd is named "ArcHydro", so that could confuse things. But the .gdb is named after the .mxd, not the project folder. I keep the rawdem raster out in the project folder as well as other layers no part of the Arc Hydro process. Cheers! Mark     ... View more

If you fill sinks, the areas in small catchments for individual drainage inlets (catch basins) will be filled in and you will loose the definition. However, if you don't fill sinks you could have local sinks inside the small catchments that would interfere. Have you burned pipes as streams? Burning  pipes as streams will avoid filling these local sinks. One problem with burning in the pipes as streams, though, is you do loose definition of the "interior" small catchments that are served by an individual catch basin. If there is a way to limit how much the sinks are filled, then you might be able to find a happy medium where you fill the minor sinks just enough to make the watershed delineation work for interior small catchments to catch basins. I've use Arc Hydro for larger watersheds. My process is to burn the pipes into the DEM prior to filling sinks. Then the flow direction is done. After that, other steps such as flow accumulation are used to define catchments. These processes don't define a particular watershed. You use batch points or another method to delineate those. I think there is now a more complex Arc Hydro process that allows you to define points for catch basins that remain as sinks and then you use another grid or polyline dataset that defines the subsurface pipe system. I would think this requires accurate storm drain pipe and inlet datasets. I'd love to have time to learn this, but it is more refined that I have time (or good data) for. For Arc Hydro, see possible solutions in this thread: https://community.esri.com/t5/water-resources-questions/archydro-problem-solvers/m-p/499200#M2431 ... View more

Sorry. I don’t yet use Pro. I don’t have access to my ArcMap right now and am out until 11/28. ... View more

Stream burning is simply creating a raster using a line (agreestream) giving it a big value, and subtracting it from the rawDEM. If you want to make it a more gentle drop into this “slot”, or make sure cells near the slot drain to the slot, you can make a polygon from the agreestream with a buffer and also make it a raster and give it a small value and subtract it from the first burned DEM. Walls are the opposite: You make a raster from a line with a large value and add it to the DEM. The agree steam would also need to be used as the breach line and so you would make the wall raster value zero at the intersection of the wall. Note that to block flow with a wall it needs to be at least two cells thick to stop diagonal flows. A stream can be one cell thick since you can have diagonal flow (flow out of a corner of the cell). ... View more

I have not ventured into Pro yet. Sorry. ... View more

See possible solutions in https://community.esri.com/t5/water-resources-questions/archydro-problem-solvers/m-p/499200#M2431 ... View more

I have not worked with Pro. I have had Geoprocesses crash when the project is on a server. But when I put the project on a local drive, the crashing doesn’t happen.  ... View more

Michiekoy, I see that your post at  https://community.esri.com/t5/water-resources-questions/how-to-burn-stream-in-dem/td-p/1196635  is similar to this.  I haven't used the openstreet map datasets, but we have one for our County that was created by someone who, it was rumored, manually digitized the creeks off of ortho photos and possibly did some on-the-ground observations. I've found that is inaccurate in many places. What I've learned from using this creek layer is that I should not rely on line work by others to define the stream where the DEM can do it for me. Why? Manual delineation has a different accuracy than automated delineation. The digitizer could be looking for a general definition of the stream while you want something accurate. Also, streams do move and your DEM might reflect something more recent. Also, a manual delineator can get confused in areas where trees hide things. What I would do now, is take the a road layer and select the road segments that intersect the streams. Then I would buffer the selected road segments  for some distance. Then use that buffer to extract stream polylines assuming they are culverts. I would check that these stream polylines line up with the low points in the DEM along the creeks/rivers. Delete or move them as needed and minimize their length where possible. Then I would manually add lines to the agreestream layer in areas like wide flat floodplains where the DEM is poorly define and photos are clear. No doubt, this can be a lot of work. ... View more

To me, in your first image in this latest reply (Capture.PNG) the red lines on the DEM show a very good match compared to the first image you posted with the red lines on the ESRI topo. There is one obvious mismatch where it looks like you drew a blue line. Possibly this is a very flat plain where the DEM has poor definition. To can train the DEM to follow an actual creek or river, or to make it flow correctly "through" a road embankment at a road crossing, you need to "burn in the streams". The process to follow is to draw lines in a dataset called "agreestream" where ever you need to force a stream to be. This line should start and end on DEM cells that are correct to make sure there is good "continuity" between where the DEM gives you right answers and where you need to correct it. You don't have to put in lines for every stream in the DEM. You only need agreestream lines where the DEM is not "hydrologically correct". You can't always see this so it is a trial and error process. Then you run the DEM Reconditioning with the agreestream dataset which lowers the DEM elevation where the streams need to be. Then build walls if needed. Building wall works the same as burning streams using a dataset named "innerwalls", but it results in a DEM where the cells are raised to stop flows from going where they shouldn't. Then fill sinks. Don't worry if the streams are burned really deep (-1000) or walls high (+500). The fill sinks will raise the DEM enough. The walls will still be high, but in the end you are not needing the right elevation, you are needing the right flow direction. You would always use the original DEM for elevations any way. The final agreeDEM will be "hydrologically correct". After you fill the sinks the DEM should be "hydrologically correct" and the flow direction>flow accumulation and later steps should result in what you want. If not, add/adjust agreestream lines or innerwalls and repeat.  The highlighted steps in this screen capture of the ArcHydro menu shows the steps I use up to Stream Definition. I'm not sure if you are going beyond that. Years ago (2012!) started a thread call "ArcHydro Problem Solvers" where I documented what I learned about ArcHydro "the hard way". Others added value to this and it is a good resource. The process I've used described there: https://community.esri.com/t5/water-resources-questions/archydro-problem-solvers/m-p/499209#M2440  Good luck! Mark ... View more

I took a screen snip of your map and drew blue lines where the ESRI topo would show the streams. Freehanded these, so not that pretty. Then I drew fainter green lines from your red lines to my blue lines where they visually seem to match in shape. It looks like your red lines are offset almost like someone stretched the image of the redlines to the east (or compressed the topo in the East-West direction). What does it look like overlaid on your DEM? Can you provide a view with the red lines overlaid on the DEM where the DEM has a high contrasting color ramp? Does the ESRI topo line up with your DEM?   ... View more

Check the projections on your source data as well as your data frame. They must be the same. ... View more

I don't know if this is the issue you must fill the sinks. Otherwise the flow direction will result in cells that don't flow downstream and the resulting drainage line layer be as you described. If you haven't burned in the streams, you may have roads crossing (or other anomalies) in your otherwise good DEM. If these are elevated above the surrounding DEM defined "valleys" the flow direction will stop at the crossings and you will get results as you described. ... View more

Is Raster Cell Iterator only available in Pro? ... View more

There is the flow accumulation tool, but that doesn't do what you want to do. It just sums up the number of cells the flow to each cell. ... View more