Sequential Checkdam modeling
Sequential Checkdam modeling
(OP)
I have been trying to model 4 checkdams in sequence 100ft apart on 6% slope. The swale is trapezoidal with a 12'BW x 30'TW x 3'D & 3:1 sides. The check dam H is 2' and spans the width of the swale. My problem is that I can't get the peak flow rate down without overtopping the swale at each Check Dam. The dimenions used above are the last ones I tried but I have used other dimensions with the same results. I started with 6bw x 22tw x 4d & 2:1 sides with a 3'H check dam - which I did get to work! I want to flatten out the sides and not be as deep for safety reasons. I have tried putting pipes through the weir, and exfiltrating but that's not doing the job. Any ideas would be appreciated.
Thanks
Stioffan
Thanks
Stioffan





RE: Sequential Checkdam modeling
RE: Sequential Checkdam modeling
RE: Sequential Checkdam modeling
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Sequential Checkdam modeling
Ok, I ran this with your geometry and flow rate.
At a 6% slope, the storage length at 3 ft deep is 50 ft, so there is too small of a storage volume to make any significant attenuation before the water reaches the top of the weir.
Your conclusion about a pond is correct. At this slope, there is too little storage. An outlet large enough to prevent overbank will never produce significant storage. An outlet that restricts flow enough for attenuation will quickly cause a water surface elevation rise at this slope (a culvert that would halve the flow rate would bring the water surface to about 8 ft deep)