Yellow River: Facts on File

["Ricardo Duchesne" <rduchesn@xxxxxxxx>]

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