TR-20/WinTR-20 Reservoir Emptying Time

[FarvAC91]

Hi all,

Just have a simple question about the reservoir emptying time output within WinTR-20. I've tried Googling a solution and have looked through various manuals, but I can't seem to find a clear explanation. Does anyone have an explanation on how to interpret the output? The general format is:

Elevation (ft)...Flow (cfs)...Storage(acft)...Time to Empty (hrs)

For example, what would my drainage time from elevation 763 when my output table is this:

Elevation (ft)...Flow (cfs)...Storage(acft)...Time to Empty (hrs)
......760..............0.0........................0.0.....................-----...........
......761.............0.169..................7.628...................1092.3..........
......762.............0.248.................15.827..................1544.4..........
......763.............0.308.................24.819..................1950.0..........

Maybe there's an easier way to do this?

Thanks

PS- I know those emptying times are ridiculous, just using an example from TR-20 with a single 4" restrictor

 

[puzzler77]

Given the rate of flow out of the storage pond, those "Time to Empty" estimates appear about right! If you are not that patient, you might try increasing the amount of flow that is permitted to leave the pond. It takes about 12 hours to drain 1 acft with a flow rate of 1 cfs. That's 43,560 cubic feet divided by 3600 s/hr.

 

[puzzler77]

What you show here are parameters for a pond. Routing a flood through the pond is what we are interested in. A small flood may only get to 761 whereas a larger flood may get to the 763 elevation. As flow enters the pond, the level of the pond increases and begins to flow (albeit, a small amount) out through a restricted opening. This is done to prevent damaging downstream structures from increased runoff upstream.