Tuesday, August 3, 2010

Using Hydraflow Express for Channel Calculations

Source: http://bimontherocks.typepad.com/


I was working through a predevelopment time of concentration yesterday using Civil 3D and Autodesk SSA, and I needed a cross sectional area and wetted perimeter for a natural channel.

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In Civil 3D, I had my TC path drawn, and using the terrain model, I could see where I entered into channel flow. I used some quick profiles across the channel, some surface analysis and slope arrows to help me get my bearings. 

Then, I made a short alignment across a representative section of the channel. You could make as many as you’d like.
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By making an alignment, I could make a profile and profile view as well as labels. I traced the existing ground profile with a layout profile to get more crisp tangent lines, then used profile labels for 1:Z slopes. I used Seth’s trick of using line labels as dimensions to give me some of the other pieces I needed to calc the CSA and WP.
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Then, I launched Hydraflow Express from the Analyze tab in Civil 3D.
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It was easy to enter the bits I needed for the calculation thanks to my profile view labeling. I could have added a few more labels- such as invert elevation, etc. if I wanted to get more information from the calculator.
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As you experiment with Autodesk SSA, don’t forget about the tools in Hydraflow Express. There is no wrong way to use the tools in your toolbox- find the combination that gets you what you need for your design.

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