Water velocity from gradient?
Water velocity from gradient?
(OP)
Hi
I'm looking for a really simple formula that will give me stream velocity from gradient (and ignore, for now, other factors, such as channel shape and roughness). Any ideas?
Thanks
Don
I'm looking for a really simple formula that will give me stream velocity from gradient (and ignore, for now, other factors, such as channel shape and roughness). Any ideas?
Thanks
Don
RE: Water velocity from gradient?
Velocity = sqrt(2*g*H)
g=9.81 m2/sec
H=Head Loss, m = (slope in fraction) * (Distance travelled)
Now, you notice it for youself that velocity goes on increasing with distance.
But no such system of "channel" has actually been experienced where you can ignore friction. I am just being curious, what do you want to do with this correct but useless equation?
RE: Water velocity from gradient?
I have a whole set of streams with gradients, but no info for the "roughness" or friction for the streams. I was hoping to be able to derive at least something for stream velocity, based purely on the gradient, but as you show, velocity increases with distance making this useless!
Do you by any chance know if anyone has derived an average friction coefficient for hydrologic flow? This would at least give me a starting point for my application, pending being able to get friction data.
Thanks again.
RE: Water velocity from gradient?
Approximate values of 'n' are
concrete =0.014-0.018
steel = 0.01
Earthen channel (smooth) =0.03
Channels with vegitation=0.05
You can refer to Ven Te Chow's book "Open Channel Hydraulics" for details.