Tuesday, November 16, 2021

Not 100 per cent

It's a hard thing to know ... when is 100 per cent not 100 per cent.  I saw on the news this morning that a dam is currently at 104%.  Does that mean its' overflowing?  It didn't sound like it was ... and if it isn't full (to overflowing) then why is it over 100% capacity?  

(Pause for research.)

The full supply level of a dam, when it is at 100 per cent capacity, is the approved water storage level of the dam for drinking or irrigation purposes.  But a dam can hold much more or much less than that.  According to a report in the ABC News in 2019, the Ross River Dam reached a capacity of 244.8 per cent. 

Who knew that dams could be gated or ungated.  The report went on to say that if a dam has a gated spillway, it can be opened to release water; for un-gated dams, operators have no control over the water that flows over the spillway once the dam's water level surpasses the full supply level.

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