Centerline of the highly meandering Creeks/Streams

[mkn]

Hi all,

I am dealing with this following situation:

The creek is highly meandering and it is very long. Thus, to relatively reflect the surface of the creek and the the floodplain, I had to cut an excessive amount of cross sections, and spent a lot of time to modify the cut lines in order to avoid crossing each other.

I understand that if the floodplain is straight and for high flow analysis, it is reasonable to ignore the meandering, the center line of the creek could be drawn straight through from downstream to upstream, and the cross sections just need to be perpendicular to this straight creek’s center line and the floodplain (perpendicular to the flows direction)

However, how do we define the straight flood plain? To what extent the flood plain is called straight? In my case, I have got ponds, swamps, embankments, dams located adjacent to and along the actual low flow invert of the creek (the meandering center line). Is it still valid to ignore the meandering and model the creek as a straight one? Please note the flow to be modeled is 100yr ARI

Anyone has experience of these issues please share.

Thanks

Kha Nguyen.

[Chris G.]

It’s really a judgement call on your part. Ideally you’ve been out to your river and have seen it at relatively high flow. But most of the time we don’t have that luxury. So you need to use your knowledge and experience on how water moves through river systems. Draw flow lines that capture your perception of how water will move through the system at high flow. Then draw your cross sections so that they are perpendicular at all locations to the flow lines (this will most likely require doglegging them). Please review this:

http://hecrasmodel.blogspot.com/2012/07/how-to-draw-cross-sections.html

Good luck-
Chris G.
@RASModel

[Author]

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