hi i need some advice please. Our lake is down 8 inches in a couple months since the golf course its on fitted a new irrigation system which uses the lake water as one of its sources to water the course. The lake has a surface area of 9 acres. I have calculated that equates to water loss of roughly 9000m3 . However the golf meter only reads just over 1000m3 . An 8 inch drop in 9 acres is not 1000m3 of water . Now it seems our calculations consistently are 9x what the meter says. I know think the true figure could be x10. This makes me think that the pumps meter is not setup properly, I have no idea how they work . I have a picture of the meter dial but I've never posted a picture on here so if someone can help that would be great. This is the meter
link
Could it be wrong

In reply to Post #1
Are you allowing for evaporation? It hasn't rained here in 2 months, an awful lot of that 8 inch loss could be due to the hot weather/wind/no rain.

In reply to Post #1
I think the golf clubs meter is correct by my maths.

3x3 to give you 9 for the 9acres, x the depth which would be 0.2 for the 8inches.

3x3x0.2=1.8.

If the clubs meter readings are just over 1000, and as Enut has said evaporation, then that would easily add the missing digits to give you the 1.8.

In reply to Post #1
I make a .2 metre drop to be 7284 cubic metres.
Evaporation as already said will be a significant loss.
Wind will pull off a lot of water vapour, probably more than heat from the sun so I can quite believe your drop.
Also is the lake lining sound? Possibly some seepage adding to the loss.

In reply to Post #4

Thanks for your replies,

so let me get this right , lets assume the 1026m3 meter reading is correct.. so the lets then assume our calculation is 8932m3 based on the drop of 8 inches roughly.

so 7900m3 is being caused by evaporation/wind etc. We have never had this happen so dramatically before and at the same time the irrigation system starts getting used, very suspicious.

so 7x as much water is lost by evaporation/wind/seepage as opposed to it getting pumped directly out the lake through a pipe to fill a massive water tank daily? i cant quite believe that

In reply to Post #5
you say the golf course uses the lake for one of it's sources.

8 inch = about 7284 - 1026m3 meter reading so about 6000m3 ish

the course will need extraction licenses stating how much water can be taken, how many sources of extraction have they got and is the other source influencing the lake water, aquafer etc

In reply to Post #6
its allowed to take 20m3 per day using that source

In reply to Post #6
Agreed, 8 inches (0.2M) from 9 acres is approx. 7,284 cubic metres.

If it helps I have a large pond and it is down a similar amount in the last 2 months, purely due to evaporation.

As stated I don't think anything is wrong with the meter, it's evaporation. IMO

In reply to Post #5
If you are really that suspicious and of course meters can be bypassed, then if you can get a look at the pump plate, pipe size, length, head from lake that to the tank, I can work out the flow per hour for you if that helps.

Also add in any foliage or trees if present will be sucking up their share moving from winter into spring/summer

In reply to Post #10
One of my waters is only small, about an acre or so. It's spring fed. I reckon that's down about six inches on normal levels. That's without any pumping, I'm guessing it's just a lack of run off due to record low rainfall, evaporation due to the hottest may on record and a lowering of the water table.

In reply to Post #11
My thinking too. After 6 weeks of really hot dry weather I think that 8 ins drop in level is nothing to worry about. Rivers, streams and ponds in my area are all down.

In reply to Post #12
Thanks for all your responses guys

In reply to Post #5
My pool is already about six inches down, purely from evaporation.
The fact that they've pumped at the same time as the evaporation has been at an unusually high level is sort of an obvious knock-on effect.