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Clark Barlow

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Clark Barlow last won the day on July 26 2010

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About Clark Barlow

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  1. You'll might also get this error if your initial moisture is higher than the porosity for a particular soil type. Just something else to check.
  2. Chad- This error usually means that you have a stream segment that has no vertices. Vertices represent computational nodes in GSSHA, and each stream arc must have at least one vertex, or computational node, to run. I'm not sure why the model says you have a negative outlet slope because as far as I've seen, the outlet slope has nothing to do with it. Simply add another vertex to the arc (I usually redistribute the vertices along the arc and set the number of segments option to 2) and rerun and it should work. Clark
  3. Ludek, I agree, this sounds like a bug in GSSHA. I would suggest contacting the model developers to report the bug. You can find their contact info on the GSSHA wiki page: www.gsshawiki.com Thanks, Clark
  4. First of all, you would probably have a better match if you contoured the TIN instead of the DEM. Depending on what resolution you chose when you created the DEM, you could potential lose some elevation detail during the resampling process. Actually, I'm not sure why you needed to create a DEM at all. When extracting cross-sections for HEC-RAS in WMS, you do this using a TIN, not a DEM. So if your extracted cross-sections are a poor representation of reality, there must be something funny going on with the TIN. One thing you could do is turn on the display of TIN triangles. This will show you what the underlying TIN surface looks like and should explain a lot. One possibility is that when converting shapefile contours to feature objects, then to a TIN, if you do not "redistribute vertices" along the feature arcs, the TIN ends up creating long, thin triangles between the contour lines that result in a poor elevation surface. Redistributing vertices is key in order to space out the triangle vertices, but you also want to be careful not to spread them out too far so as not to lose horizontal detail. I hope this helps. Clark
  5. Some of you may have noticed a strange occurrence in WMS where one of the WMS tools (zoom tool, select polygon tool, etc) gets stuck in rubber-band mode. This means even when you aren't clicking and dragging the tool, WMS will draw a selecting box with the tool as if you were! Unfortunately, we haven't pinpointed exactly when or why this happens. We have good news though- there is a workaround! The answer is to simply launch another instance of WMS from the start menu. Once WMS opens, close the WMS window and once you're back in your original project, you'll notice the rubber-band line is gone. If I were you, I would then save my project, and continue working as before. Good luck! Clark
  6. Hi Lily, We are aware of the new version of CE-QUAL-W2. We have not yet tested this version for compatibility with WMS which is why we don't yet distribute it. We expect to make this evaluation sometime in the near future. Clark
  7. Lily, I use WMS 8.3 on a Windows 7 machine and I don't seem to have any problems related to compatibility with the OS. Is there a reason why you need to install CE-QUAL-W2 separately? CE-QUAL-W2 version 3.2 and 3.5 get installed in the WMS folder when you install WMS. I've never had a problem doing this. Are you trying to install a newer version of CE-QUAL-W2? Please provide more information so we can better understand your problem. Regards, Clark
  8. Shiva, If you're not using the rainfall grids to derive a basin average rainfall depth, it's hard to say what the problem might be without looking at your model. What other processes are you trying to model? Have you tried sending the model to tech support? Clark
  9. Shiva, Your document suggests that you're using radar rainfall. Is this so you can derive a basin average rainfall value, or are you using the radar rainfall grids to distribute rainfall over the watershed? Clark
  10. Thomas- You can do this in WMS. It involves editing the DEM elevations using an arc. See our online help page for more info: http://www.xmswiki.com/xms/WMS:Editing_DEM_Elevations -Clark
  11. Thomas- Yes, you could do this as well. The only drawback to this method is that it often creates a very abrupt transition between the overland area and the stream channel, creating artificially high slopes along the stream bank. This can throw off some of the parameters WMS computes for the watershed, such as mean basin slope. But if all else fails, you could try this, particularly if the model you're running doesn't depend on the slope-related parameters. -Clark
  12. You have a couple options. You could turn on your flow vectors and adjust them around your area of interest until you get the stream to show up. You do this by double clicking on a DEM cell and changing the flow direction arrow. Another option is editing the DEM elevations. For example, if you have survey data of the area, you could merge that with the DEM in hopes of TOPAZ defining the stream in that area correctly. I hope that helps. Clark
  13. Rob, I haven't used flow change locations much in unsteady flow. It seems though that if the tributary enters the main stem after your flow change locations, then the flow change should be entered simply as the total flow at that point. If the flow change locations occur downstream of the confluence, then you would also have to account for the tributary. I have a good feel for how this all works in steady flow, but again, not really for unsteady. I don't know that this affects your boundary conditions. It seems that if you use a flow time series upstream (on both the main stem and the trib), and normal depth for the ds boundary conditions (on both the main stem and the trib) that this should work fine. I guess I don't see how your boundary conditions would be affected by the flow changes. Sorry if this response is completely useless to you. Feel free to clarify if there's something I missed. Thanks, Clark
  14. Rob, Yes, you do need to make sure your flow changes correspond to the event you're trying to run. If you're getting 50-yr flood stages with seasonal low-flow boundary conditions, then it could be that your flow changes are adding way too much flow. You could also fool around with the boundary conditions, e.g., change the ds boundary condition to normal depth and see if that drastically changes your results. Clark
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