John F Dean wrote:I am dividing 1478mm by 25mm and getting 59 inches of rain. That is quite a lot in my world. I suspect our numbers are off somewhere.
If that amount is correct, and the problem is the rain is seasonal, then a well designed pond should help a great deal. I would think about adding a cistern for drinking water in addition.
Anne Miller wrote:A lot also depends on the type of soil you have.
Is your soil mostly clay?
Where I live ponds will not stay full unless there is a pond liner.
I have an empty pond as the water just drains out after a rain. My theory is that the soil is rocky and the rock allows the water to drain out.
We tried adding bentonite clay though this did not work for us.
To fill a pond I have heard of folks bringing in water to fill it rather than wait on rain.
Other folks might create a pond where there is rainwater rushing across the property.
You or others might find this of interest:
At the high point of the property, water is rushing in whenever it rains. This water is cutting a deep channel through the property. The crew decides to capture this water and use it to create an oasis!
https://permies.com/wiki/148356/Ponds-movie-World-Domination-Gardening
John F Dean wrote:Much depends upon your expectations. You never say how much rain you actually get.
I live in a area that gets 46 inches of rain a year. I have a pond that i estimate to be about 1.5 acres and 20 ft deep. In summers with low rainfall the surface has dropped 4 to 6 ft due to evaporation.
Based on the above, I doubt if a pond will be your solution, but it may be part of the solution. I am working off the assumption that some water is better than none.
As for reducing your evaporation, reduce the surface area and increase the depth. Some kind of covering might help.
Years ago I saw a system set up on a steep slope where there was a pond built into a hill side ( mountain side) to take advantage of the runoff from the slope. The pond had an 8 inch spillway pipe that emptied into a covered above ground swimming pool.