Latest Contributions by MarkBoucher

‎07-16-2015

Come explanations regarding Catchments vs AdjointCatchments and Watersheds vs. Subwatersheds are here: Catchment vs watershed

‎07-15-2015

Esther, Welcome to Arc Hydro! Catchments are Arc Hydro's basic watershed delineation of the agreedem based on the strlnk raster. A Catchment polygon is created for each confluence of the DrainageLines (or for each DrainagePoint). The number or density of the DrainageLines is based on the number of cells you chose in the stream definition step. The fewer the number of cells, the more "dense" the DrainageLine features (these come from the strlnk raster) and smaller the Catchment polygons. After the Catchments are created, the AdjointCatchments are created. Each successive AdjointCatchment polygon consists of the next downstream Catchment. So the AdjointCatchment polygons overlap where as the Catchment polygons do not. The purpose of the AdjointCatchment polygons is to make delineation of the watersheds and subwatersheds fast; very fast compared to delineating them without the adjoint catchments. Basically, the AdjointCatchment polygons are "pre-delineated" watersheds that make future delineations relatively quick compared to how the were originally done. The DrainagePoints, DrainageLines, Catchments and AdjointCatchment (I think that's all) are part of a geodatabase network that Arc Hydro builds. If you study the DrainID and HydroID fields of the various vector feature classes you will see that there is a relationship there that associates them. These are used for the network. With this network, Arc Hydro can delineate a watershed quickly. When you process a watershed or subwatershed at point using Arc Hydro Watershed Processing tools, the area upstream of the point is "chosen" using the upstream AdjointCatchment polygon and then Arc Hydro only has to do the "tedious delineating" of the agreedem for a small part of the dem that is downstream of the AdjointCatchment polygon. This "tediously delineated" area and the AdjointCatchment area are combined to make a Watershed for the point that was processed. As the story goes, when the Arc Hydro team demonstrated the use of a network in watershed delineation at a conference, the conferees thought it was a trick because it was so fast. Before that, the delineations took a laborious amount of time. At least that's what I heard from ESRI during training. Of course, you can use the Catchment and AdjointCatchment polygons for other purposes. Best, Mark

‎06-24-2015

William, Welcome to the ESRI-PYHO (Pulling Your Hair Out) club. I feel your pain. Glad you got around the problem. Creating a new mxd has helped me several times. Mark

‎06-23-2015

Glen, I've just got a few minutes and then need to head out of the office. This is a very common error that could mean a number of things (not that I know what they are!). I did a little search and found a thread on the error. c# - What is a NullReferenceException and how do I fix it? - Stack Overflow I guess "Object Reference Not Set to an Object" can also be called "Null Reference Exception". Subheadings at the link above seem to make more sense than the techno-talk in the post. It looks like the error comes up when the program runs across a "Null" value in a variable. Make sure the features have values in key fields. Naming conventions is one that I've found is important. In the screen capture you posted it looks like you are using default names and they don't have any spaces. Sometimes the name length can cause problems. You could try creating a project directory that is not as "deep". I use C:/GIS/<Project> for my work. I save the mxd with relative paths and then move the project to a server that is backed up later. Don't have more time to help. Sorry! Mark

‎06-12-2015

Ganesh, I'm very happy you were able to get it to work. Nice to know that others are contributors regarding Arc Hydro. I'm no expert unless you consider an expert someone who is willing to wrestle with the pig until he figures out all the tricks to get it under control. Happy pig wrestling, Mark

‎06-11-2015

Ryan, Can you upload the raster file or attach it to a post? I see an option under my profile icon to upload a file to share. I've not done this before, but it may be the best first option. Mark

‎06-11-2015

Ganesh, Did you reset your processing extents via Geoprocessing>Environments>Processing Extents as I mention in my Feb 26, 2015 8:52 AM post to Ryan (above). When I see a raster "cut off" like that, my first thought is the processing extents got messed up. My most memorable situation was when the limits of the resulting dem were a rectangle that matched the extents of the BatchPoints I was using. I'm not sure what part of the Arc Hydro process might change the processing extents. However, it could be that the values are NOT cut off. The white area could be positive numbers in your highest elevation classification. If you classify with a different color ramp you will likely see that the white area is not "blank" as happens when the extents are wrong. Maybe one of the intermittent steps resulted in a cut of one of the intermittent rasters due to the extents changing and subsequent steps reflect that "missing" part of that cut off DEM. In your case something looks really strange because your elevation values in the AgreeDEM are very negative in general and you have "spots" all over that are dark making me think they are negative. I've never seen this before. A step I take sometimes is to use the Spatial Analyst tools like raster calculator on the SA toolbar (you have to add it to the toolbar) to subtract one raster from the other (Agree DEM - rawdem). In a normal situation this will show you where the process has raised or filled in the DEM. This is really handy to see places you may need to add a stream such as at a culvert embankment that "blocks" a stream. Occasionally this will reveal something you couldn't see otherwise. Sorry I can't be of more specific help. If I were you I'd make sure to save the agreestream, innerwalls, outerwalls, batchpoints and rawdem layers, etc., and delete everything else and start in a fresh mxd. When I do this I delete the folders, geodatabases and all. This would make sure the extents, tempfile locations, target locations, etc. are all set. They should be setup again automatically by the Arc Hydro process. Coordinate systems need to also match. I have not dealt with a vertical datum conflict issue and that is one very remote possibility, especially seeing how your elevations "inverted" for some reason. Best, Mark

‎06-02-2015

I've had Arc Map crash in the middle of editing a model (very frustrating). I've never tried to recover a model that crashed. I hope you can find a solution! I've seen the "can't save" message before. I don't recall it not saving and not giving me any other option. I use the "save as" command under the "Model" menu in Model Builder. This lets me save a copy of the model under another name. Then I close down, start up, delete the old model, and rename the newly saved model. So much time and $ goes into these things, that it is real letdown to loose the work. On a big model, it would make sense to save a backup copy once in a while. I'm not certain, (and only ESRI knows), but I think the occasional problem with saving has to do with the file locks. Somehow the temporary file locks (write permissions) get mixed up and the program thinks you are trying to save the file someone else has open. I've had this happen on models as well as MXDs. I find that with the ESRI products one has to assume there are inherent file instability and management issues that warrant caution and prudence to reduce file losses: backup at milestones, save often, pray, etc.

‎05-28-2015

Nice work! I use a raster that is floating point, and have never run into a problem with it. FYI.

‎05-27-2015

I worked back from error line 34 where …\fillGeo does not exist. It looks like fillGeo is created from a process done on leveldem. First of all I'm not an expert at sleuthing the error messages. However, I looked through what you posted and see a few things. There is a layer with the name c:\hydro\raster\leveldem. It appears in the Process Log and in the first error message on line 27. The rest of the errors cascade from there. If there is no leveldem then there would be an error reading it. If it were the wrong type (integer instead of real or vice versa) you might get an error. In the Process Log there are temp files (probably rasters) with names tmpsink, nullSinkGeo, and notnullSink. I also see the “ISNULL” in the Process Log. This makes me think the fill sinks command checks for null values in the walled/burned DEM. This might be the leveldem, but you’d have to check your process. This makes sense because you'd think that trying to fill a cell with a null value might cause some equations to choke. Maybe there are cells in one of your DEM’s that have bad or missing data. The line 35 “Failed to execute (Con)” message supports this. The Con() function is a conditional function like an if-then statement. I’m not sure if this function is data type sensitive (Integer, Real, alpha). That is, I’m not sure if it would produce an error if it was checking the condition for a Real value when the value is an Integer. I don’t think a raster can have an alpha value unless the value “Null” would be an “alpha” type (which I don’t think it is). The ISNULL() function is used with the Con() function often as in Con(ISNULL(leveldem), …,…). All of this could lead to an incompatible raster type for you DEM. Most DEM’s are real but DEMs can be integer. Could also be that the "Failed to execute (Con)" error occured fillGeo does not exist (see line 34). Anyway, those are my rambling thoughts on this.

‎05-27-2015

I've used outerwalls before (v 9.3?) and had no problems. More recently I extract the rawdem out of a countywide DEM by mask around the watershed and leave it up to Arc Hydro to set the ridge boundary. The only time I really had to build an outerwall was back with I used 9.3 and the creek in the flatlands ran right next to the boundary. It would "spill" out of the boundary w/o a wall there.

‎05-26-2015

The cause could be a number of things. Working with your mxd and other data on your local box and not over a network saves time and eliminates errors. There are several tips at https://community.esri.com/thread/43771 that might be helpfull. Mark

‎05-26-2015

Langdon, It looks like your innerwalls portion is working but your outerwalls portion is failing. You could try copying your inner walls data to another feature class, delete all the data, copy your outerwalls to the new feature class and use the new feature class for the outerwalls. If this fails, the something else is wrong besides data type or fields. I always keep this data (agreestream, innerwalls, outerwalls) in a geodatabase. Geodatabase datasets are more "stable" than feature classes. Mark

‎04-30-2015

I just posted something about Target Locations at Re: Batch point generation not working. As for the storing the raster in a geodatabase: This can be done, but Arc Hydro, be default, keeps the raster data in a separate folder. See the link above regarding target locations.

‎04-30-2015

Arc Hydro uses "target locations". These are locations where the raster and the vector data is written when it is created. This keeps you from having to create folders and a geodatabase and also telling Arc Hydro where to put/get data. The BatchPoint features should be written to the geodatabase and dataset for the vector data. If these targets are not set correctly, Arc Hydro will possibly put the data in the wrong place and even overwrite a previous project's data! Below is a copy and paste from a doc I wrote for myself a while back and just updated slightly to help keep target locations straight. Hope this helps: ********************************************************************************************************************* If you are starting a new mxd and adding the dem and vector layers to start your Arc Hydro project, Arc Hydro will set the Target Locations automatically and you don't have to mess with them. If you want to check them they should follow the pattern below: Given: mxd path = C:\MyProjectFolder\ mxd name = MyProject.mxd data frame name = MyDataFrame (The default is "Layers" in all mxds. If you change the data frame name BEFORE running any Arc Hydro function or else you will need to reset the target locations.) You can check the target locations using the Arc Hydro tool bar menu: ApUtilities>Set Target Locations>HydroConfig Map Level Map Name: MyDataFrame Raster target location path: C:\MyProjectFolder\ Vector target location: C:\MyProjectFolder\MyProject.gdb With these settings, the raster data is stored in a folder: C:\MyProjectFolder\MyDataFrame and the vector data is stored in a geodatabase and feature dataset: C:\MyProjectFolder\MyProject.gdb\MyDataFrame When you look under ApUtilities>Set Target Locations>HydroConfig should be the target location setup. If you save the mxd and data to another location, you will need to make sure the target locations are corrected or else the results of the Arc Hydro functions will end up in the old target! This will be confusing for Arc Hydro and may lead to other errors. There is a utility the resets the Target Locations. This is really handy. If you move the mxd and data, you can reset the target locations using the following utility: ApUtilities>Additional Utilities>Reset Target Locations

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My Ideas

Latest Contributions by MarkBoucher

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Re: Catchment vs watershed

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