Latest Contributions by MarkBoucher

‎06-06-2011

Have you run the fill sinks function? I think the burn streams function only lowers the DEM where the streams are by a constant value. If there are localized low points in the stream, you would still have localized low points in the stream. The fill sinks function would fix this problem. Also, if the stream is not "wide enough" (at least 2 cells), you might have similar problems (though I'm not certain about this). Mark

‎05-31-2011

I found out that my streams has breaks. Are you using the DEM Manipulation functions under Terrain Processing? If the streams are discontinuous, and you haven't burned in the streams, stream crossings such as bridges or culverts may cause a rise in the DEM that will "block" the flow direction and "stop" the stream. Mark

‎05-25-2011

Arc Hydro takes the Flow Accumulation (fac) and with a Stream Definition function allows you to put in the number of cells at which to start a stream. Then with Stream Segmentation and then Catchment Grid Delineation you get a catchment grid. Another function converts the grid to polygons.

‎05-06-2011

Make sure you don't have anything selected before that process is started. Running from model builder sometimes reveals more feedback, though it is not all that descriptive most of the time.

‎04-27-2011

Check out http://forums.arcgis.com/threads/28817-calculate-distance-between-points-along-stream-network

‎04-27-2011

I've seen several threads about Arc Hydro not working as expected. On a few of them I've responded the same way. I'm in the middle of an Arc Hydro project and I am finding functions not working as expected just like a I see on a lot of these posts. My solution is as follows (it works almost every time): Arc Hydro may be trying to create temp file that already exists. In my Arc Hydro training at ESRI I was told that, when things start going "funny": close ArcMap, go to your temp directory - In Windows 7, mine is at C:\Users\mboucher\AppData\Local\Temp delete everything you can. You can tell if this is where the ESRI program puts temp files, by: open the folder, sorting by date (new to old), and starting ArcMap. If this is the right directory, you will see temp files being created. There are some files that you can't delete while other programs are running, so you may have to close all programs to delete all the files. There was usually one or two that I cannot delete. I assumed it was related to Explorer. You can also delete files using Arc Catalog. Using this you can see the temp rasters, etc. When this does not work. I close Arc Desktop and use Arc Catalog to delete shape files and rasters that I'm needing to create. I do this to ensure that there are no write protection errors causing problems. I'm using Arc Hydro in Arc Desktop 10 with Windows 7. Cheers. (P.S. - ESRI, if you're listening, please fund those guys working on Arc Hydro so they can build in some safeguards against these kinds of problems! We've got better things to do than rant at our computers over these things! Thank you!)

‎04-27-2011

The longest flow path function is part of ArcHydro. It is free. May take a little while to learn it though.

‎04-27-2011

The longest flow path function is part of ArcHydro. It is free. May take a little while to learn it though.

‎04-22-2011

Could you use the cost distance tool in Spatial Analyst? Use the stream to set a low cost in a raster along the stream and high cost elsewhere. Then do a cost distance calculation along the stream with a source grid at one end. Then then pick the cost off the resulting grid where the points are and take the difference in cost distance between points. (?)

‎04-18-2011

C:\Users\mboucher\AppData\Local\Temp. To find this directory you may have to change your Windows Explorer settings to show hidden files. In Windows 7 this is under Organize > Folder and search options > View tab > Hidden Files and folders > Show hidden files, folders, and drives.

‎04-18-2011

In my Arc Hydro training with ESRI I was told that, when things start going "funning", get out of ArcMap, go to your temp directory and delete everything you can. Then start up again. This has cleared things up for me many times. In Windows 7, mine is at C:\Users\mboucher\AppData\Local\Temp. You can tell if this is where the ESRI program puts temp files, by opening the folder, sorting by date (new to old), and starting ArcMap. If this is the right directory, you will see temp files being created. There are some that you can't delete while in other programs so you may have to close all programs to delete all the files. There was usually one that I could not delete. It's name became familiar and I assumed it was related to Explorer. This was such an issue for me at one time that I had a shortcut of the temp directory in my tray and opened it all the time to make sure ArcMap/Arc Hydro wasn't frozen. Hope this helps.

‎03-18-2011

The stream layer is a polyline layer. The "walls" are known watershed boundaries and this is the form of a polygon layer. I recall trying to use a polyline layer for the walls at one time and having it work, but I usually use a polygon layer. What Arc Hydro does is, it takes the DEM that streams are being burned into and it reduces the elevations of the cells that intersect the streams polyline plus the buffer(s) by the amounts you set. Then the elevations of the cells the wall polygon perimeter intersects (or the wall polyline intersect) are increased by a amounts you set (use at least 2 grid cells). The final DEM, in fact, can have very deep streams and very high walls. The goals is not to create a perfect DEM from which accurate contours can be made. What you want is an accurate flow direction grid. That then becomes the basis for your flow accumulation grid, etc. I do the fill after burning stream and building walls just to make sure the bottoms of the fill streams don't have any localized low points that will mess up the flow direction grid.

‎03-09-2011

The DEM will not give you the same stream network that you created by digitizing unless the topography is extremely well defined (deep and well defined valleys). You will likely have to "burn" the digitized streams into the DEM first, and then fill sinks. This is called "terrain processing". the After you have processed the terrain, then will be able to continue the process of defining your watersheds. I use the tools in Arc Hydro to burn streams (Terrain Processing > DEM Manipulation >Reconditioning), build walls, then fill sinks (see Terrain Processing > DEM Manipulation) to create a "hydraulically correct" DEM. In the flat lands burning streams an building walls is essential for creating a hydraulically correct DEM.

‎03-07-2011

We are planning on keeping a 9.3 version on a separate machine so we can use GeoRAS as needed. I believe we will continue to use HEC-RAS. It runs independently from GeoRAS. Since HEC-RAS is at the core of the Corps' Hydrologic Engineering Center (HEC) work, they will likely continue to developed it. Also, there is a new RAS Mapper feature in the latest version of HEC-RAS that might aid in presenting results using a "flt" DEM. I have not used it myself, but a tech in our office has looked at RAS Mapper and it seems to work; though I don't know how well or how the results can be transferred back into ArcMap for display purposes. (Is HEC moving to make its own GeoRAS type tools independent of ESRI?) I have no insider information. However, I suspect the costs associated with ERSI's continual changing of ArcMap, (not just upgrading, in my humble opinion), and the economy, etc., the Corps can't afford to keep throwing money at ESRI to upgrade GeoRAS and GeoHMS. ArcHydro is ERSI's baby and so ESRI will likely keep that updated. If I may vent... If I were in the private practice, I think the licensing costs for ESRI products and the cost of training and retraining users would be killing me! Though I like some of the new features in v10, having to re-learn the editing tools, how features work, etc. (the frustrations of losing Map Book for something that lacks some of Map Books features for example) are tough on my budgets and schedules. In other words, forget finding a replacement for HEC-RAS and GeoRAS (free software by the way), is there a competitive alternative to ESRI products? --- There. I'm done.

‎03-02-2011

We were just given computer upgrades and I went to install the latest HEC-RAS version (4.1.0) and noticed on the Corps software page that this version has a "RAS-Mapper". A tech here looked at it and HEC-RAS it appears to take a DEM Float file (.flt) (convert TIN > DEM flt in ArcGIS) and use that to plot flood extents. This almost looks like a work-around from GeoRAS. With the cost of the ESRI software licensing, I can see why the Corps might move some of this functionality into HEC-RAS. I'm not driven be a project to check out the RAS Mapper, maybe some of you are at that point and could report. See basics on RAS Mapper at http://www.hec.usace.army.mil/software/hec-ras/hecras-features.html

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My Ideas

Latest Contributions by MarkBoucher

Re: Watershed delineation

Re: Watershed delineation

Re: Create 'sub basins/catchments' of a defined size

Re: ArcHydro 9 & 10: Adjoint Catchment: Empty Feature Class

Re: Distance to Next Downstream Point

Solving Arc Hydro Problems by deleting TMP Files

Re: Flow Length �?? Understanding Output Raster

Re: flow length tool to calculate the longest stream in a watershed

Re: calculate distance between points along stream network?

Re: Catchment Polygon/Adjoint Catchment Problem

Re: Catchment Polygon/Adjoint Catchment Problem

Re: subbasin creation using arc hydro

Re: subbasin creation using arc hydro

Re: HEC-RAS and ArcGIS 10 dilemma

HEC-GeoRAS - RAS Mapper

Re: Sub-watersheds delineation cut off in straight...

Re: Conversations with Jack: GIS and Hydrology

Re: ExtractByMask - Script to include pixels whose...

Re: ExtractByMask - Script to include pixels whose...

Re: Point Delineator tool in Archydropro