Interesting Stuff: Yellow River

I’ve recently finished reading the wonderful Behind the Wall by Colin Thubron. Thubron was one of the first westerners to travel to the recently-reopened post Cultural Revolution China of the 1980s. It is a fascinating account of the mere glimpses that he as an outsider could obtain on the aftermath of what’s possibly one of the most tumultuous events in history.

He also speaks of some more long-ranging items of interest. One that I wasn’t aware of was the recurrent tragedy of the Yellow River. I did know the Yellow River was the cradle of Chinese civilisation and one of the original places where human agriculture developed. As such, the river feeds some of the most important areas of food production in the world, as it has for several millenia. However, it is also known as China’s Sorrow, and has an unimaginable death toll.

The problem is apparent in the name. The Yellow River is yellow because of the tremendous quantities of mud that it carries (much higher than most of the muddy rivers). As the mud is carried for thousands of kilometres, much of it gets deposited. The end result is that the river very quickly builds up a bed of mud around it, meaning that it actually flows at a level that can be several metres higher than the hundreds of kilometres of surrounding farmland.

This presents a huge risk of regular flooding. A riverbed that’s below the landscape (which is the norm) must overflow greatly to flood. But the Yellow River, all that needs to happen is for the mud levies which hold it back to be breached at one point and the whole river goes into the tablelands, flooding an enormous area and destroying the grainbasket of China.

To top this off, once the river breaks from its riverbed, its course starts to wonder and it may take years for it to find a new one. This is a bit like what happens to a water-hose when you turn on the water pressure but there’s nothing holding it down: it begins to sputter back and forth. Of course no river course is set in stone, and geology is all about the changing of even such seemingly-stable things — but for the Yellow River it happens with great regularity. That’s why maps show its “current course”, since it changes so often and has so many periods where it’s simply undefined.

As for the death toll, it is staggering. From Wikipedia’s list of ten deadliest natural disasters (excludes epidemics and famines), Yellow River floods took the top 2 spots with up to 1.3M-4M deaths in 1931 and 2M in 1887, the 1931 one completely inundating 87,000 square kilometres of land. And if instead of all natural disasters you look at just the worst floods, the Yellow River takes all top 4 spots.

A particularly eggregious flood (#3 on the above list) was when Chiang Kai-Shek was fighting the advancing Japanese troops in 1938. The Nationalist army was low on resources and so Chiang “strategically” destroyed the levies near the city of Zhengzhou. This flooded 3 provinces, causing almost 1M civilian deaths in the country he was defending. Below is a picture of refugees from that very flood — as some civilians were rescued by Japanese troops.