Latest Contributions by MarkBoucher

Use the attribute table and the field calculator.  --  You can use the field calculator on a table column to modify the field value for just those features that are selected. If you don't select any features then field values for all features are modified.  Instead of selecting, you can use the Properties/Definition Query to limit which features are shown in the map and table. Then when you use the field calculator in the, the changes will only be made to those features that are showing. You can test this out on a copy of your data to make sure it works for you. ... View more

If you have a flow accumulation (fac) raster, (which you likely have if you've deliniated the watershed) you could extract the value from the fac raster to the points. Then you'd need to multiply the fac value by the grid area (100sf for a 10'x10' grid) to get the watershed area. With the Spatial Analyst function \Extraction\Extract Values to Points you could use the culvert point feature class (fc) and fac raster to create a new point fc that has the same fields as the culvert point fc plus a "RASTERVALU" field. After creating the new point fc you can join it with the culvert point fc using the Object ID or someother unique field (or by location) and transfer the RASTERVALU to your culvert point fc while multiplying if by a factor to get the area. Hope this makes sense. ... View more

You can accomplish this using the topology tools. You put both FCs in a geodatabase and create a topology in the same database. Then in the topology you create rules such as the FCs must not overlap and must not have gaps or mush share a border. Then you add the topology to the mxd. When you start an edit session with the topology in place and use the topology edit tools, the topololgy rules are followed and you edit both at the same time. You can use the topology tools to fine errors in the topology (where the FCs overlap and they shouldn't, etc.). It is not the easiest way to do this and there are quirks, but that is what is supposed to do. Hope this helps. ... View more

When I see "Error HRESULT E_FAIL has been returned from a call to a COM component" I immediately consider working on the project with the Arc Hydro data on my local drive and not on the network. For me this has fixed many otherwise unexplained errors and has sped up the processing significantly. I've posted this and other solutions in the link below my signature. ... View more

The topology tools might help speed this up. ... View more

Maybe you need to check if the topology error tolerance. If you raise that, would the error go away and the accuracy still be acceptable? ... View more

Based on my limited experience, with topology, if you recheck the topology after marking something as an exception, it will pop back up again as an error. I think this is because the topology exceptions are not stored in the topology. That would be really cool. I imagine it would be tough to store the exception and then keep track of which features are related to the them so that the error exception would be removed if any of the related features were modified. ... View more

When streams split, they are considered non-dentritic or deranged. In the Arc Hydro environment, there is a way to deal with deranged terrain. Look in the toolbox for Arc Hydro Tools.tbx > Terrain Preprocessing Workflows > Basic Deranged Terrain Processing. This will show you the process for dealing with deranged flows. I have not yet had to deal with this, but the tools and possibly the online help should lead you through it. ... View more

The Generate Flow Path tool right sidebar help includes text stating, "The connectivity is established by using the HydroID/NextDownID attributes in  the drainageline features." Look a the drainage line features and see if the have values in the HydroID and NextDownID. ... View more

Option 1). Can you copy the old polyline to the new layer? (edit the new layer, set old layer as only selectable, select the old polyline, copy, paste). Then edit the new version of the polyline that is incorrect to trim away the incorrect parts. Then select both and merge them. Option 2). Bring both layers in. Edit the new layer and use the reshape feature tool using the trace tool to reshape the erroneous parts of the feature to match the old correct parts. Option 3). Put old and new versions in a geodatabase and use the topology tools. Easy if you know how... ... View more

As I understand it, the purpose behind catchments, drainlines, and adjointcatchments isn't to give you the right size of watersheds for your study. Their purpose is to be a network to make the delineation of watersheds faster. Before use of the network databases, each watershed was delineated just using the flow direction grid. On the then much slower computers, this was painfully slow. Once someone figured out how to use the network functions for hydrology, the delineation of watersheds was amazingly fast compared to the old way. I heard that when it was demonstrated at a conference, it was so much faster than normally experienced, the audience thought it was a trick! The HydroID, DrainID, and NextDownID in the catchments, drainlines, and adjointcatchments are all related to the network database . Instead of focusing on the catchments, etc., you could assume they are a background "model" on which you then set batch points at the specific locations you need to study. Then the batchpoints, subwatersheds/watersheds etc. become the working layers you do you analysis with.  HEC-GeoHMS has some nice tools that compliment Arc Hydro. That's my understanding and approach. Btw, the stream definition has been puzzling to me too. I think the problems come because the flow accumulation can jump dramatically at "junctions" in the flow direction grid. For example, if you have one subshed with 299 cells, and another with 299 cells and you set number of cells to define the stream at 300, the number jumps from 299 to 599 (including the cell you are now on) and you miss the target. ... View more

Try using raster math to subtract your original dem (rawdem) from your fill dem (fil): fil - rawdem. This will reveal where the fll has been placed. Symbolizing this with a blue color ramp and making the 0 values transparent is helpful in this analysis. If your rawdem has bridges or culverts over the rivers, your rivers would be filled in behind them. If your raster is relatively flat, this filling in would make the rivers "disappear". What you may need to do before filling is to "burn in" a stream through the bridges and culverts in the rawdem. Here is one response to another question that I think explains how to burn in streams. I use Arc Hydro, but it can be done "manually". http://forums.arcgis.com/threads/103449-How-you-work-if-not-have-a-streams-layer?p=368696&viewfull=1#post368696 You can search the hydro forum or the Arc Hydro forum with the word "burn" and you will find several other posts on burning. ... View more

I've found I can get lock issues if I'm looking at the data through some other software: Arc Catalogue, Windows Explorer, etc. Make sure they are closed and see if you still have an error. ... View more

See http://forums.arcgis.com/threads/104391-New-password-for-Arc-Hydro-ftp-site-March-11-2014?p=376913&viewfull=1#post376913 ... View more

In my Arc Hydro experience, the rasters used in Arc Hydro go to a folder with the same name as the Data Frame. The vector data goes in a dataset with the Data Frame name inside a geodatabase with the mxd name. The rasters do not go to a geodatabase. ... View more