Vegetation-Erosion Dynamics - River Dynamics and Integrated River Management - page 97

Fig. 2.43 Vegetation-erosion charts for the four areas in the Loess Plateau in China: (a) Area I- Sandy and hilly area
along the Great Wall; (b) Area II- East loess-hilly and gully area; (c) Area III- West loess hilly and gully area; (d) Area
IV- Loess Plateau gully area ( Ʒ - Present status of vegetation and erosion; '- Present status of vegetation and erosion
in Area II excluding Yan-an city)

self-restoration. The main strategy is intensive reforestation. Once a relatively high vegetation cover has
been achieved the vegetation is self sustainable and human management is only needed to avoid
deforestation. For other three dry and cold areas (Areas I-III) in the Loess Plateau the strategies of
watershed management should be as follows: ķ Planting trees to reduce erosion. The straight line
' E is steep, thus, reforestation may easily move the status point into the Zone D, in which the erosion

rate may automatically reduce. ĸ Managing artificial vegetation carefully. Because Zone C is small,
vegetation is not stable even when the vegetation has been greatly improved and erosion has been
reduced. Management is always needed to maintain the vegetation. Neither reforestation nor erosion
control are effective for further vegetation development. Reforestation can be applied as an effective
strategy to control erosion but vegetation development must rely on human effort.

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2.3.4.2 The Yangtze River Basin
The Yangtze River is 6,300 km long and has a drainage area of 1.80 million km 2 . From the source to
Yichang (Three Gorges Dam site) is the upper reach, from Yichang to Hukou (Poyang Lake mouth) is the
middle reach, from Hukou to Datong is the lower reach, and below Datong is the estuary. There are
562,000 km 2 of land experiencing soil erosion in the upper reaches of the river. The annual sediment
yield from the upper Yangtze River basin is 2.2 billion tons (Tang, 2004). Glacial erosion occurs in the
Qinghai-Tibet Plateau and serious rainfall erosion occurs in the Yunnan-Guizhou Plateau. For