After a few days of leaving the pond overflow pipe open to drain the nearly daily falling rains, the rains tapered off. And since the pond water level looked like it could go up another 50cm without causing any problems around the land, this afternoon I decided to close it to see how quickly it would rise.

At that time, the water level was at the bottom of the pipe.

A few hours later, an incredibly heavy downpour began, and when I checked the overflow pipe about an hour later when the rain tapered off, the water level had risen above the top of the pipe. It was getting a bit dark, but here is a picture:

Since the pipe is a 4″ pipe, and the water level is nearly 5cm above the top of the pipe, this means that the water level rose about 12cm (5″) in such a short amount of time.

This is consistent with reports recently of rainfalls in excess of 14cm per day in areas in and around Bangkok.

Needless to say, I decided to open the valve again.

I was pretty surprised that the rain came down so hard, the large urns that we collect rainwater (that probably can hold about 250L of water each) filled up very very quickly:

The roof feeding the above urn is about 6m x 4m. So if the rainfall fell by about 12cm, this would mean that 6*4*.12=2.88 cu. m. of water came down. That comes out to 2880L. So it is no surprise that the urn filled up so quickly.

It is worth mentioning that the tap we installed at the bottom of the urn to drain water out into a hose was left open. But the water flowed in much faster than the small valve could drain it out.

Here is another urn that is fed by the larger roof in the front of the house:

This roof might be about 14m x 6m. In this case, not only did the urn fill up almost immediately, but the rain gutter feeding it was overflowing. This means that the 4″ hole couldn’t pass the water out fast enough to keep the rain gutter from filling up!

Well, at least this was an exceptionally heavy rain. And after the rain stopped, the various drains we built did a good job of letting the water out of the yard and into the neighboring canal. This way the trees we planted won’t die from sitting in a pool of water for the next few days. So no real harm done.

If you want to imagine what it is like, just imagine stepping under a strong shower head, except the shower head covers… everywhere. 🙂