Latest Contributions by MarkBoucher

After digging even deeper into the data, I may have discovered the problem. For some reason, my stream and stream links are not connecting the paths together- and when I turn on the drainage line layer- that feature class is just line data of these two rasters overlapping.    So how do i get one solid stream network to appear, and not have the mainstream itself become disconnected? (Str was a cell size of 500, Str2 was 1000, Str3 was 1200, and Str4 was 1500; StrLnk was created from Str4)       ... View more

Jan, Sorry about using the odd terminology. Yes. I is a raster manipulation so that the flow direction grid is hydrologically correct. I would not assume a flow direction raster derived from a "raw"DEM would be correct. Filling the sinks is a raster manipulation, no? Arc Hydro calls all of this "DEM manipulation" with a subset of "DEM reconditioning". So the steps with or without Arc Hydro are: Obtain a rawdem (you already have). Delineate "agreestream" line features where you want the streams to be "forced" through road crossings or where underground pipes are. You don't have to add lines where the DEM will accurately a creeks or river (unless the river is really wide and you want the flow path to follow a certain thalweg. Make sure your lines through the road embankments connect to raters outside of the embankment.  Burn the streams: The term "burn" is the actual term used be ESRI in Arc Hydro for "lowering the elevation" of the DEM where a line is. Arc Hydro does this in the background, but it is basically defining a raster where the line is (line to raster conversion resulting in 0=no line, 1=line; the DEMLine in this conversation), then multiplying that raster by a large number (default in Arc Hydro is 1000, but any large value will work) then reducing the original DEM (rawdem in Arc Hydro terms) by subtracting the DEMLine from the DEM. Fill sinks: The "hole" burned where the streams were defined by lines through embankments will be filled up no matter how deep they are. Run flow direction tool and check. Adjust agreestream line features and repeat as needed. If you define a stream next to a "natural stream" that could be defined by the raster and your stream is does not line up with the natural stream, you could end up with parallel streams and the flow direction could bet confused. I had one result in flow directions that were backwards! So, watch out for this. There is a way to correct the flow direction, but that is for another thread. I have used Model Builder to do this work since it can be repetitive on larger areas. Arc Hydro is free. If you don't have admin rights to install it, ask IT. It is worth that hassle. Arc Hydro has a lot of tools and I haven't had to use all of them. https://www.esri.com/content/dam/esrisites/en-us/media/technical-papers/archydro-overviewofterrainprocessingworkflows.pdf  One of the steps I have used is Building Walls: Make a walls line feature class and place lines where you need to build walls to "block" flows from going a certain direction: Delineate a "walls" line feature ("innerwalls" and "outerwalls" in Arc Hydro). This is the opposite of burning streams. You make a line raster from the "walls" layer(s). A key here is to "breach" those walls where the "agreestream" lines are. Take a bit of creativity in the geoprocessing procedure, but is do able. May be able to do a raster calculation making the walls raster 0 where ever the "streams" raster is 1 before you multiply the walls raster by a large number and then add it to the elevation dem.) I've had to do this at railroad tracks that were not on an embankment, but where culverts conveyed flows across the tracks. The tracks were so low that the filling and resulting flow direction easily ended up with flows going right over the tracks at the wrong place. Building a "wall" along the tracks and burning a stream where the culvert was solved this. ... View more

Hi Mark,  Thank you for your unreserved replies to all the posts here. Could you provide the model builder screen shoot with good quality so that we can easily adopt and solve the problem. Thanks. ... 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

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

did you solve it? If you solved it, can you write it? ... View more

In simple terms, the answer for the original question is this: The user controls the minimum drainage area required to form the beginning of a reach. This is the same as defining the average areas of the headwater sub-basins. This is done when you set the threshold in the stream definition. After that, the user does not have control over the size of the downstream sub-basins, because the distance between reaches, or streams, is what drives it. Hence, the downstream sub-basins can be much larger, or much smaller than the initial threshold set on the stream definition. ... View more

Hi Christine,   Is there a version of ArcHydro that will run in the ArcGIS Pro 3?  With the change in code for this release, I suspect that the old versions will not work.   Sean ... 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

I see that the Python tool for LFP for Adjoint Catchments also requires LFP for Catchments as input.  Was this with a different version?  Has the memory leak been addressed?  I'm still getting an error like this. ... View more

Hi Tania, thank you for your suggestions. Flow Accumulation doesn't fit my needs.  In my raster, each cell represents the time that the drop of water takes to cross it. I have to calculate, for each cell, the total time obtained by adding the times of each cell from the current to the outlet, following the flow direction. I drew a figure to explain what I want. Marco ... 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

Thank you for the information Mark, I actually found your discussion in my searches previously, and I ended up making my own thread as a last resort because nothing was working.  It's holding up my work flow currently and I am trying everything I can think of along with every suggestion I have found in other discussions but can't seem to find anything that works.  I have even tried running it on other computers and I feel stuck.  Do you know if the DEM has to be in a specific format or if there's any prep I have to do with it beforehand?  The data itself is the only thing I can think might be the issue at this point, but it seems to work for other agencies so I'm a bit at a loss.   ... View more