Re: Yellow River: Facts on File

[Michael Perelman <michael@xxxxxxxxxxxxxxxxx>]

You can't tame rivers, but you can take care of the land on the hillsides
to reduce siltation.

Ricardo Duchesne wrote:

> I have come to the conclusion that China's hydraulic lock-in and
> long term patter of development cannot be fully grasped without a
> clear appreciation of the ecological dynamic of the Yellow River.
> This, the most unsubordinate, intractable, turbulent river of the
> world, has long driven a hard bargain. In exchange for its heavily
> sedimented water,  the fruit that nourished the Shang, the Zhou,
> the Chhin, the Han, the Sui, and the Tang civilizations (to 907AD),
> it killed more people than any other river in the world.
>
> Here are some facts on file:
>
> -- The Hwang Ho, with a lenth of 2,900 miles, is China's second
> largest river, and the 10th longest  in the world.
>
> --Carrying up to 40 percent sediment by weight (in some stretches
> as much as 60 percent), it is the most silt-laden river of the world.
> Sediment over 10 percent by weight is very rare among the large
> rivers of the world; even 2 to 3 percent is high (Cressy, 1955).
> Much of the silt is loess, a fine wind-blown soil which the river
> picks up in its upper course as it flows through the "yellow earth"
> region. "Much of this silt is then dropped in its more sluggish lower
> reaches, building up the height of the river bed, and making its
> course unstable" (Blunden and Elvin, 17)
>
> --While the Yangzi River discharges a greater volume of water, the
> Hwang Ho is much more unstable in its flow; at low water, the flow
> may drop to 5000 cubic feet per second; in flood it can reach
> 1,000,000 (Cressy). But the most challenging engineering aspect
> is control of the exceptionally high sediment. As the river passes
> through the loess lands and erodes the loess, it becomes a river of
> yellow mud which is then deposited across the North China Plain.
>
> -- To deal with this shifting, sediment-loaded river, dykes were built,
> to keep the water stable, but as a result of dike building, the
> surplus sediment which nature would have otherwise  spread far
> and wide has been confined between artificial barriers. Thus the
> bed of the river has been continually raised requiring dikes to be
> built higher and higher. This dyking has gone on indefinetely.
> Millions now live below the level of the diked floor water. Areas
> miles from the river have elevations many feet below the bottom of
> the river.
>
> --But this river refuses to be tamed. Not only has the river's levees
> been breached thousands of times, its lower course has changed
> 26 times in China's history. A highly devastating change of course
> occurred in 1194 AD  when flood water rushed onto the Huai River
> basin taking over this river's drainage system for the next 700 years
> (Leung, 1996). Siltation at the mouth of the River has extended the
> length of the river by about 35 miles betweern 1975 and 1991.
>
> -- By the 1950s the northwest province of Shensi had 13 modern
> canal systems, with a total length of 600 miles. Currently the
> Chinese are constructing a massive new dam called Multipurpose
> Dam Project with 10 intake towers, nine flood and sediment
> tunnels, six power tunnels and an underground powerhouse.
>
> --The floods of Hwang Ho are the most destructive, since they
> persist for long periods and spread over the countryside in every
> direction (unlike the Mississipi where the flooded areas are usually
> a ribbon between the river and its bluff). When the flood ends, a
> veneer of sand and mud covers everything except for the few tree
> tops which had remained above water. While the Egyptians referred
> to the annual flooding of the Nile as the "Gift of the Nile", the
> Chinese have nicknamed their unruly Hwang Ho "China's Sorrow".
>
> --When the river's current  slows, and the river loses its carrying
> power, excessive sedimentation takes place within a few days. The
> bed of the river is thus raised. When the next flood arrives, dikes
> are overtopped before there is a chance for the increased
> movement of the water to excavate previous accumulations.
>
> -- No amount of dyking can entirely eliminate the wide variations in
> its flow, which to an extent seen nowhere else in the world it is
> also a flow of mud. Each year 1,890, 000, 000 metric tons of silt
> are brought to the head of the delta plain. "The control of the
> Hwang Ho is surely one of the most baffling hydrologic problems on
> earth; were the river in the United States it would tax all the
> country's financial resources and engineering skills" (Cressy).
>
> -- Two million lost their lives from drowning or starvation after the
> flood of 1888. But too little rain can be worse than too much.
> Serious draughts have been a regular occurence in the dry north,
> particularly the provinces of Hopei, Honan, Shansi, Shensi, and
> Shantung, where 100 out of the 216 greatest draughts have been
> recorded

--

Michael Perelman
Economics Department
California State University
Chico, CA 95929

Tel. 530-898-5321
E-Mail michael@xxxxxxxxxxxxxxxxx