Pond drain time

[queque]

POND SIZING-- assuming a pond is full with a 3 ft. depth, a storage of 0.5 acre ft and a 6 inch orifice at the bottom,
how does one calculate the time to drain?

The assumed elevation of tne .5 ft diameter orifice centerline is 5.25 ft.

 

[psmart]

Assuming you have already modeled the pond in HydroCAD, you can see the draw-down by examining the elevation column in the tabular hydrograph.

If you need help setting up the pond, just enter your data including the desired starting elevation. Set the time span to start at zero hours and watch the pond drain. You do NOT need an inflow hydrograph - all your water will come from the starting elevation.