Here is a picture of measuring the level of the water relative to the sand retention wall.

You can see that the water level is about 60cm from the top of the wall. My target water level is 10cm higher than the top of the wall. But the way we built the wall, it shouldn’t be completely water proof. (It is meant to retain sand, not water.) So it might be possible to turn on the pumps even before the water level gets above the wall.

The pond is like a large saucer that is still only partially full, so the water level rises faster than the rainfall rate because it is collecting a larger area of rainwater and funnelling it down to the bottom. Based on this Thai Meteorological Dept webpage it looks like on average one might expect another 20cm of rainfall this year. This may result in about 30-35cm higher water level between now and the end of the year, so the pond will still be about 30cm from the top of the wall.

Just for fun, here is a picture from yesterday:

Pond level on Oct 22, 2015

And for comparison, here are two pictures from late May and early June.

Pond level on May 22, 2015. No water yet.

Pond level on Jun 9, 2015. Just a shallow puddling.

The bottom depths to the shallow walking ledge about halfway up is between 1.5m and 2m of height. Then, the sand retention wall is another 1.3m up from the shallow area ledge. So based on the measurement that the water level is 60cm down from the top of the retention wall, the pond has filled up to a depth of somewhere between 220cm and 270cm from only rainwater over just the past 5 months.

For comparison, my native Los Angeles has been in a drought for the past few years and has averaged about 18.5cm of rainfall per year since 2011.

To my friends from L.A., if you are thirsty, you are always welcome to come over to my place for a drink of water.