Wednesday, April 15, 2009

We Get It, But We Don't Get It

Out in the countryside about an hour or so from Chengdu is the city of Dujiangyan. Over 2,000 years ago, this otherwise obscure river town was the site of a water diversion project that changed the course of history in this part of the world.

From the beginning of human history, the Min River has come cascading out of the Sichuan mountains, periodically causing devastating floods. Seeking a way to tame the Min's water, a local official came up with the idea of building a levee in the middle of river, as a way of dividing the water into two separate streams. This artificial island was originally constructed out of long baskets of woven bamboo that were filled with stones and held in place by tripods made of wood.

The benefits of many years of hard labor were felt in a number of ways. Not only did the second stream provide a kind of escape valve for surging flood waters, but it also had the effect of diverting water out to the arid Chengdu plain. This irrigation allowed for the area to be transformed into a fertile region that has long been one of China's most populated and prosperous.

Spending a few hours at this World Heritage Site made for a beautiful outing, although all four of us have to confess we had a hard time figuring out just how Dujiangyan was built and how it actually functions. It's just so much easier for us non-engineers when it comes to a modern dam...Build a wall, and then the water can't get by unless you open the door.

Speaking of dams, I have heard it mentioned that, at least at one point, there were plans to construct a dam upstream a bit from Dujiangyan. Even this non-engineer can understand that the yu zui levee, despite it's other advantages, does not serve as a source of hydro-electric power...



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