Dust flux, Vostok ice core

Dust flux, Vostok ice core
Two dimensional phase space reconstruction of dust flux from the Vostok core over the period 186-4 ka using the time derivative method. Dust flux on the x-axis, rate of change is on the y-axis. From Gipp (2001).

Friday, February 19, 2016

Water resources in ancient China

Guangzhou has been an important city for at least 2000 years. The capital of the ancient kingdom of Nanyue was within modern-day Guangzhou. The former palace grounds were excavated starting in 1995, and have been turned into a museum, not far from the main business centre of the city.

The first thing you see on entering the museum is the excavation of the former gardens, which had a pond and a series of waterways.

One thing I really noticed was that there were a lot of former wells on the site. Water is, of course, fundamental. The philosophy of Chinese labour can be summed up as go out, plant rice, and dig wells for water.

These wells show different styles in the way the sides of the well are lined, the sophistication of the tiling or brickwork around the well, and the styles of the stone curbs, suggesting that these wells have been placed sequentially over a period of nearly 2000 years. The most recent well was emplaced during the Qing dynasty, which ended in 1911.

Qing dynasty well.

The above reproduction of an aerial photograph of the former garden/pond/waterway shows the number of wells (small circles).

A few years ago, we decided to dig a well on our property in Ghana. We put down a nice circular hole more than a metre in diameter over three metres down into the aquifer, which was a coarse sand. We used a couple of lengths of concrete pipe to line the lower part of the well, and lined the wider upper section with chicken wire, which we used to support concrete. We laid bricks around the well, and built a concrete curb to keep surface water from contaminating the well. It worked pretty well until one night a terrible storm created such a surge in the aquifer, that sand liquefied and flowed up the well, basically to ground level. That sand undermined the laterite around the well, which collapsed, disrupting all the brickwork. I had a picture of the final mess somewhere but can't find it.

Anyway, for this reason, I have a lot of respect for someone who can dig a well that still remains 2000 years later.

That is really fine work.

No comments:

Post a Comment