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W Beck

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  1. Hello, I am attempting to use WMS / HEC-RAS to determine the threshold discharge for overbank flow in a third-order watershed. This is part of a floodplain sediment storage study. I am running a series of flows through the model and trying to determine the minimum discharge required to initiate overbank flow. I am assessing the overbank threshold visually, using flood depth contours (generated within the _fd dataset). I assume the presence of any flood depth contour ≥0 represents overbank flow in my WMS model (see attached image 1). I also assume that stream reaches without contours present are not exhibiting overbank flow. I should note that I inserted field-measured cross sections into my model. I have three questions: 1.) Can you offer any advice regarding visual (or non-visual) methods of determining the incipient point of overbank flow? I assume if there was a way to indicate top of banks in relation to flow depth, this would be helpful (e.g., a non-planform view of the cross section and associated flood depths). For image 1, the contour range is 0 (min) to 1 (max), with 5 intervals. 2.) The flood depth contour polygons often exhibit a width that is nearly equal to the channel width in my watershed model (Image 1) - so, how can I be sure the flood depth is not being calculated within-channel? Again, I'd like to know if the flood depth is occurring in the floodplain and not in-channel. 3.) I have noticed that many "isolated" flood depth contours appear around cross sections, even at flows that I would not expect to be out of bank. Any thoughts on this? See image 2. Again, I am interested in determining the minimum discharge needed for overbank flow. Any advice on this non-traditional use would be greatly appreciated!!! Thank you.
  2. I am at the point where I am able to run steady flow analysis for my HEC-RAC .prj file. However, during the initial stage of post processing, WMS "freezes up" after I select HEC-RAS --> Read Solution. The message "(Not Respoding)" is displayed in upper region of the screen (see attached image). The 2 error messages (attached) also appear. I let this continue for 15-20 minutes before force quitting WMS. Some history: I was originally performing the analyses on my laptop, and was able to get a bit further in the process (i.e., the 2-D scatter point files were created) before WMS "froze" and indicated "not responding". Thus, I added the program to my desktop (Windows 10.1), transferred files, and attempted the analyses once more. On my desktop, when attempting to access my .prj files via "HEC-RAS --> Load Project", I am now given the same error message as above (this did not occur on my laptop). I am able to access open my .prj files, but in a round-about way (i.e., HEC-RAS --> Start --> Open --> select .prj file). I am not sure if this has anything to do with the issue. I created a new .prj file on my desktop, and reran steady flow analysis with the same results. Any thoughts? Thank you.
  3. I extracted my drawn-in cross sections from the TIN to create a new cross section database (in prep for HEC RAS). When saving and exiting my .wms file, I was given the following error message (image below). Should I be concerned with this, and if so, how do I address it? Why did this occur? Thank you.
  4. I created a HEC-RAS network schematic, and was in the initial stages of running HEC-RAS when a series of errors occurred. These errors stemmed from the fact that some of my cross sections did not intercept the left overbank (LOB) and / or right overbank (ROB) lines (middle image). Compare to the top image, where the cross section intercepts both LOB and ROB. I did not realize this was critical when creating the cross sections in WMS. Extending the cross sections beyond the LOB / ROB would seem to solve the problem. As you can see in Image 3, when the cross section does not intercept one of the bank lines, it assigns both bank stations to the zero point. My question is - is there a way to edit the cross sections (i.e., extend them) after a network schematic has been created? Since I merged all extracted cross sections with field data, I'd hate to go back and redraw all cross sections, extract again, and then merge again. I attempted to draw extensions onto the cross sections in WMS (create feature arc tool, then use "node-to-vertices" option to create a single line), however, this seemed to "unlink" the cross section with my merged data. So, is there a quick way to extend cross sections beyond LOB / ROB centerline coverage, to eliminate the HEC-RAS errors? Without having to redraw / extract / merge all cross sections again. Thank you!
  5. Chris, Thank you for the advice. I ended up removing points from the extracted cross section prior to merging - this worked nicely.
  6. I am attempting to align (merge) my DEM-extracted cross sections with field survey cross sections (step 6.4 in "Managing HEC-RAS Cross Sections" tutorial). Can you provide any general rules of thumb when attempting alignment? I have attached a series of screenshots to illustrate my questions. Shot A: I have added the field survey cross section (dark line) - I have offset it so you can see it better. Notice that on my field survey, the west top bank is lower than the east top bank. For the DEM extracted cross section (light line), the east and west banks are generally on the same level. Should I line up east bank (DEM) to east bank (field survey), as in shot B? Or, should I line up west bank (DEM) to west bank (field survey), as in shot C? If I line up west-west (e.g., lowest bank-lowest bank), and then align using "insert all", the resulting cross section is odd looking (shot D). Will this odd shape affect the HEC-RAS model? So, my field-survey cross sections do not perfectly match the DEM extracted cross sections, making for an uneven overlay. Is it more important to line up the lower or higher top banks prior to merging? Any advice on merging cross sections would be great. Thank you.
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