Swale Maximum Velocity at Outlet 1

[martin888888]

Creek restoration project on the downstream 1000' where we are widening the channel and placing rip rap. Velocity in channel gets as high as 11-12fps. Install energy disipation measures at confluence with major waterway. Energy disipation includes wideing channel, placing larger rip rap, and possibly check dams. Are there certain velocities you want to meet before a waterway discharges into another?

 

[swm25]

You want to get the velocity down to the velocity of stormwater in the channel that you are feeding into.

 

[cvg]

ideally, the same velocity would be nice, but seldom possible and not essential. however the design water surface elevations should be approximately equal. you need to analyze the hydraulics of the junction including peak flow combinations, momentum lost in the junction and make sure you do not have freeboard issues, standing waves or other wave effects, hydraulic jumps, etc. then provide energy dissipation / erosion protection as required. the USACE has a good design guide for this.

chapter 4
EM 1110-2-1601 HYDRAULIC DESIGN OF FLOOD CONTROL CHANNELS