Stream Meander

[kjcdc090385]

Designing a stream to replace an existing shallow closed donduit sewer. The new stream is to have several minor meanders and pass the 1 year storm. After that, the stream banks will overtop and cause the area to pond. My questions is, how do I calculate an acceptable radius of curvature and meander wavelength so it is not to sharp or frequent? Channel is to be trap. with 2.5' base 2:1 sides and 0.9% slope. 1 year peak is 32 cfs.

 

[gbam]

You need to evaluate the water surface super elevation due to your curve radius as well as any potential scouring within the curved section. These are direct functions of your radius. Are you meandering to miss obsticales or for the heck of it?

 

[kjcdc090385]

meandering for the aestetics and DEC would like to see it mainly. What are the functions.

 

[emmgjld]

From the standpoint of one with a geology background.
I would look for similar sized and gradient streams/creeks (cricks?) in similar soils and see what the natural 'meander is.

 

[gbam]

Grab any open channel hydraulics text and look up superelevated flow in bends and it will provide you with the procedure. As to the scour, take a look at FHWA's HEC15 Design of roadside channels. It will walk you through the stable channel design.

If you slope is flat enough (low velocity) the channel may not scour or superelevate through the bends.

 

[Ryb01]

try these following references...

Stream Restoration, A Natural Design Handbook, prepared by the North Carolina Stream Restoration Institure and North Carolina Sea Grant

THE WES Stream Investigation and Streambank Stabiliaztion

or as gbam said.....any open hydraulics text


With a design crieria of a 1-year storm, you can check for super elevation but the increase in water surface elevation will be minimal. If your super elevation difference is more than 1-2" for your channel, you'll need to review your design as your probably going to erode the channel banks to due high velocities.

Checking erosion thresholds is a must. Look at other watercourses in your area and try to mimic existing conditions where ever possible (i.e. similar grade, channel cross section, vegetation,granular material, etc)

 

[Drew08]

Find any reference by David Rosgen and Wildland Hydrology, including NRCS NEH-654, Chapter 11.

He is the self-proclaimed master of all things of stream classification and rehabilitation.

http://www.wildlandhydrology.com/html/references_.html

 

[beej67]

I thought you had to pay the $$ and take the Rosgen class before you could get at his methods/books/etc. Are they available online?

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[Drew08]

Sure Rosgen has turned his ideas into a business, which is making him rich, and his published books are for sale, but he can't prevent you from using his ideas as long as you give him his credit.

How often do you use the Manning's equation? Did you ever spend the $30 to pick up his paper describing it? No, then how do you know what it is?

Despite some critics, his ideas are becoming mainstream and are not hard to find if you look around. In his defense though, his classes are pretty intersting, and he is an interesting character.

 

[debgallery]

to expand on what emmgjld said but by no means putting words in his/her mouth)....
you might want to look upstream (or downstream but upstream is preferred I think) of the reach that you're looking at. If it's in a natural state (i.e. not confined by a road, culverts, etc) you can survey the toe of the base flow channel to get the natural meander, sinuosity, profile and channel dimensions. If this is not an option try to find a similar stream nearby. Looking at aerial maps (Google Earth, Seamless Viewer) is a good place to start. If survey isn't an option aerial photo's can provide at least the sinuosity and meander.

 

[beej67]

Ugh. $250 for Rosgen: Applied River Morphology on Amazon.

Anybody know where I can nab a PDF of it?

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com