jeb6294
Well-known member
We only have a couple computers here with programs that'll do a hydrograph for the discharge from a detention basin. Lucky for me they are both laptops that tend to be out of the office a lot.
I'm trying to do a hydrograph so I can determine the orifice size to drain a given volume over a 36 hour period...stupid water quality regs. I'll try and explain how I'm doing it now, but I'm not sure how well this'll work:
Right now I'm trying to do a spreadsheet in 0.10 hour increments. Based on the orifice size you're using, it figures the Q using q=ca(2gh)^0.5 and multiplies that cfs times 0.10 hours to get the volume of water that is dumped in that 0.10 hour period. After that volume is released, the water level goes down so it repeats this process with the new "h" for every 0.10 hr period until it gets to a level where the water level is at the centroid of my orifice. Once it hits the centroid, it starts doing the same thing but treats the orifice as a weir, q=clH^3/2 (for simplicity's sake I'm using a square orifice).
Hopefully you can follow all that...seems to work fine in theory, but it just doesn't want to work though. Even if I run the time out to 48 hours, it still won't go to a volume of 0 no matter what orifice size I use.
If it makes any difference: volume is 31,363 cf, basin is 42,000 sf with vertical sides.
I'm trying to do a hydrograph so I can determine the orifice size to drain a given volume over a 36 hour period...stupid water quality regs. I'll try and explain how I'm doing it now, but I'm not sure how well this'll work:
Right now I'm trying to do a spreadsheet in 0.10 hour increments. Based on the orifice size you're using, it figures the Q using q=ca(2gh)^0.5 and multiplies that cfs times 0.10 hours to get the volume of water that is dumped in that 0.10 hour period. After that volume is released, the water level goes down so it repeats this process with the new "h" for every 0.10 hr period until it gets to a level where the water level is at the centroid of my orifice. Once it hits the centroid, it starts doing the same thing but treats the orifice as a weir, q=clH^3/2 (for simplicity's sake I'm using a square orifice).
Hopefully you can follow all that...seems to work fine in theory, but it just doesn't want to work though. Even if I run the time out to 48 hours, it still won't go to a volume of 0 no matter what orifice size I use.
If it makes any difference: volume is 31,363 cf, basin is 42,000 sf with vertical sides.
