Latest Contributions by MarkBoucher

Quick reply: Work the project with data on your local drive and not over the network. Make sure the target locations are correct. Check other tips under the link in my signature block. Mark ... View more

My SA license is not available for me to look at the commands in detail. My watersheds are generally not as flat as Florida. In the flat valley areas I do have, I find the need to "build" lots of walls to make the flows go in the right directions. I think there is an option in the burn streams tool that tells Arc Hydro to bring the negative dem values up to zero. If you do have zero values and can't find that option, but still want to see if the negative numbers make a difference, you could use the CON() function to make anything negative 0.0 or slightly above. Then you could use that raster for the rest of the process. I also don't recall negative numbers being a problem. I'm in the SF Bay area and my elevations aren't all that high. I use the default burn values which I think the deepest is 1000 ft. and I know many of my projects have gone to the bay and I've never had a problem. Since I have steeper terrain, my tendency is to minimize the width of the smooth and sharp rise values. The purpose of the smooth drop is to eliminate parallel stream right next to your main stream. It might be a trial and error situation for you to figure out what values to use. When I do trial and error, I do a trial noting the parameters I used, get out of Arc Map, delete the Arc Hydro file geodatabase and raster folder, start up Arc Map again and reprocess using different smooth/sharp drop values. Seems to be a few extra steps, but makes things run with fewer hiccups due to overwrite conflicts etc. This is where model builder comes in handy. ... View more

This post has some explanation. http://forums.arcgis.com/threads/52110-Terrain-Processing-Steps.?p=178866&viewfull=1#post178866 See also the link in my signature for other Arc Hydro tips. ... View more

Sounds like a similar topic to this other recent post. http://forums.arcgis.com/threads/103132-Obtaining-stream-flow-direction ... View more

Tony, Are you doing the work on rasters that are on a network drive? If so, try moving all the data you will manipulate to your local machine and see if that fixes things. You can find more Arc Hydro tips via the link below my signature. It is also a "sticky" in the Arc Hydro forum. ... View more

You can process the DEM without the streams. The Arc Hydro process will give you a str grid and eventually a DrainageLine polygon layer. These are is where the "streams" are per the DEM (and at the resolution of the DEM) If I were you, I would start with the Fill Sinks step and move on through Flow Direction, Flow Accumulation, and Stream Definition. At this point I would stop and see if the str grid locates the streams in the right places. If you have aerial photos that you can make out the streams on and they seem to be in the wrong places, you can add a polyline agreestream layer to "train" the DEM. That is basically what burning in the streams does. For example, at a culvert crossing the fill sinks tool will fill in the area upstream of the culvert. The flow direction and resulting str may show the stream going around the culvert. Here you would add an agreestream polyline that will burn a "slot" in the DEM to make the flows align with the culvert. There could be other places that are really flat that you need to define the stream location better. This could be labor intensive if you have a large area. However, unless you can find a stream layer from some other source, it is what you have to do. Remember, you don't have to have a polyline where every stream is. You only have to have a polyline where the DEM does not correctly define the flow path or stream. Hope this helps. ... View more

Michele, If I'm understanding you right, you have LiDAR for the river. I don't believe LiDAR can give you stream bed elevations under water. The light beams end up giving you the water surface.  I am not familiar with the  SRTM 90m data. From what I found on the web (http://www.cgiar-csi.org/data/srtm-90m-digital-elevation-database-v4-1) the SRTM DEM is created using satellite data. I'm not sure what technology they used to create it. It is a worldwide dataset so I doubt their intent was to get as detailed as you want. I would think that the 90m DEM would be inadequate for HEC-RAS modeling. I don't know what tools would be needed to get data below water (bathymetric data). You will likely need to find another data source to get the information you want. ... View more

Michele  ~  A 90 meter grid is a very coarse for a DEM in my experience. Unless you have very wide rivers, I'd think you would have a tough time accurately defining the rivers using Arc Hydro. If you are working in very steep terrain you will have better success, but even then, I'd think 90m would be too coarse. If you have LiDAR, I would create a reasonably fine DEM from that; say, 3 meter grid. ... View more

You can use the "build walls" tool. Use the road polygons as the "innerwalls" with a buffer of 1 (makes 2 cell thick wall). The height of the wall can be very large (1000'). Then you need the "agreestream" layer to include the culvert crossings for the "breach" layer. If you have pipes in the parallel to roads, you may need to be creative. One option is the make your DEM grid even finer (smaller cells) somehow. This will give you more refinement horizontally, but the elevations in the DEM should be the same vertically. With the finer DEM grid the agreestream and innerwalls layers won't "conflict" as much when they are parallel. ... View more

I need help burning my roads data into my 3m resolution DEM to generate watershed. Any help? I have a roads dataset which I have already converted to raster with the same resolution as the DEM. I need to roads to burn into the DEM with the output being a new DEM so that I can use this to delineate watershed for road culverts. Can anybody please help? Thanks. Why do you want to burn the roads in? In terms that I'm familiar with, burning lowers the grid cells in the DEM. ... View more

In don't use the sink evaluation tool, so I'm not sure what advice to give you that is not already posted. ... View more

I'm having this problem can you please help me My first advice is to not run this with the data on a network. Put it on your local PC. It speeds things up dramatically and avoids many unexplainable errors. You can check out the thread linked below my signature. Many of the common Arc Hydro errors and issues are posted there. ... View more

I think in general they are synonymous. Watershed, catchment, basin... these terms all mean the same thing, really (to me). They are confusing because these words or parts of them are sometimes used for other drainage related things: catchbasin, detention basin, watershed (as the ridge line or watershed divide), etc. ... I'm sure I'm missing others and some people may disagree with my definition of these terms since their "culture" used them differently than mine. In Arc Hydro, "Catchment" is the default name used for the the "watershed" polygons that correspond to the stream link (strlnk) grid. These do not overlap each other. In Arc Hydro, "AdjointCatchment" is the default name used for the the "watershed" polygons that correspond to the stream link (strlnk) grid. These overlap each other. They are used as part of the geo-network to make delineation of the watersheds very fast, the whole reason behind the DrainagePoint, DrainageLine, AdjointCatchments layers and HydroIDs, NextDownIDs, DrainageIDs in the first place. In Arc Hydro, "Watershed"  is the default name used for the the "watershed" polygons that correspond to the BatchPoint points. These overlap each other. That is, the Watershed polygons include all areas that drain to the point per the flow direction grid. In Arc Hydro "Subwatershed"  is the default name used for the the "watershed" polygons that correspond to the BatchPoint points. These do not overlap each other. That is, the Subwatershed polygons include only the areas that drain to the BatchPoint per the flow direction grid below any upstream batch points. If you don't like the default names, you can always change them. I used to until I got tired of doing that. Eventually, I just embraced them. Of course, this is just my understanding. You may find better information elsewhere. ... View more

Depression Evaluation Error Solution http://forums.arcgis.com/threads/102422-Depression-Evaluation-Error?p=365369&viewfull=1#post365369 ... View more