Integrated River Management - River Dynamics and Integrated River Management - page 756

soil erosion from the upper Yangtze River basin as 1.6 billion tons per year. (Tang, 2004) presented the
value of 2.24 billion tons per year. Yu (2003) adopted the value at 2.179 billion tons per year. The
Ministry of Water Resources reported the total soil erosion determined by remote sensing performed in
1990, which agrees with the value around 2.2 billion tons (ACRS, 1990). Table 11.2 lists the rates of soil
erosion from different drainage areas of the upper Yangtze River basin presented by Yu (2003), in which
the rate of soil erosion per area is the average value over the area of soil erosion but not over the whole
river basin. The Jinsha and Jialing river basins are the main sediment sources for the Yangtze River. This
topic uses the figure of 2.179 billion tons per year as the total soil erosion for the Yangtze River basin.

T able 11.2 Rate of soil erosion from different drainage areas of the upper Yangtze River basin (after Yu, 2003)

Area
(km 2 )

Area of soil
erosion (km 2 )

Soil erosion
(mil·t/yr)

Percentage in total
soil loss (%)

Rate of soil erosion
per area (t/km 2 yr)

Watershed

Jinsha River
( upper Yangtze)

488,900 223,800 829 38.04 3704

J ialing River 159,900 92,400 559 25.65 6043

T uojiang River 27,800 14,800 92 4.22 6216

Minjiang River 135,400 5,800 253 11.61 4362

YangtzeRiver
P ingshan-Cuntan

45,700 24,400 107 4.97 4385

Wujiang River 86,600 46,300 191 8.77 4125

Three Gorges Reservoir
( Cuntan-Yichang)

61,100 36,500 148 6.79 4055

Total 1,005,400 496,300 2179 100 4390

11.2.3.2 Sediment Storage in the Upper Yangtze River Basin
The total soil erosion from the upstream reaches of the Yangtze River is 2.179 billion tons per year. But
the long-term average suspended load at Yichang before the completion of the Gezhouba Dam- the first
dam on the river—in 1980 was 514 million tons, with an additional sum of bed load of 9.54 million tons
(sand bed load 8.78 million tons plus gravel bed load 0.758 million tons) (TGP Water Survey, 2005). The
difference between the volumes of the total soil erosion from the upper Yangtze River basin and sediment
load at Yichang is 1.655 billion tons. Thus there must be a huge amount of sediment stored in the upper
river basin.
The Jinsha River basin is the main sediment source of the Yangtze River, with total soil erosion of
more than 800 million tons per year. As shown in Fig. 11.42, there are many debris flow areas in the basin
and the slope in the basin is quite high. Table 11.3 lists the sediment yield from several debris flow
gullies measured at the downstream end of the gullies. The sediment yield per area from the debris flow

T able 11.3 Sediment yield per area from debris flow gullies in the upper Yangtze River basin
Debris flow Gully

Area (km 2 )

Sediment yield per
area (t/km 2 ·yr)

Period of
measurement

References

Guxiang Gully 26.00 470,020 1964-1965 Wang and Zhang, 1985

Liuwan Gully 1.97 124,970 1963 Yang, 1985

Huoshao Gully 2.03 126,100 1973 Yang, 1985

Niwan Gully 10.30 65,500 1965 Yang, 1985

Hunshui Gully 4.50 374,240 1976-1978 Zhang and Liu, 1989

Jiangjia Ravine 48.60 142,200 1965-2002 MWRC, 2000