Environmental Engineering Reference
In-Depth Information
high net increase. The installed capacity of hydropower makes up about 25% of the total installed capacity
with large hydropower stations each with the capacity of larger than 250 MW being about 50% of the
total hydro in both installed capacity and annual energy output. The share of hydropower has tended to
decline relative to the total power capacity and output. Most of large thermal power stations are located
at the coal mine heads in the northern China (Shanxi, Hebei, Henan, and Shaanxi Provinces), though
some are also located near load centers such as Shanghai and Guangzhou. Most of the large hydropower
stations are located in remote mountainous regions in the upper reaches of the Yellow River, Yangtze
River, and the rivers of the southwest. In each region, the share of hydropower varies greatly, being
particularly low in the northern and eastern China, and significantly higher in the northwest, central
southern, and Fujian and Sichuan provinces. The Three Gorges Project, currently under construction, will
add 17,800 MW by 2007. Nevertheless, only 17% of the total exploitable hydro-power resources of
China have been exploited. Dam construction in China is still in the developing stage. This is different
from developed countries, where people are discussing decommissioning of dams.
1.2.7.2 Irrigation
China is a large agricultural country. Irrigation and drainage play a very important role in the agricultural
production. The country may be divided into five categories of areas: very humid, humid, semi-humid,
semi-arid, and arid. The country may also be divided into three different zones based on the different
requirements of irrigation/drainage for agricultural crops, that is, a perennial irrigation zone with less
than 400 mm of mean annual precipitation, an unstable irrigation zone with mean annual precipitation
between 400 mm and 1,000 mm, and a rice irrigation zone with more than 1,000 mm of mean annual
precipitation. The perennial irrigation zone covers most parts of northwest china and the upper and
middle reaches of the Yellow River, composing 45% of the land area of the whole country. The unstable
irrigation zone covers mainly the lower reaches of the Yellow River, the Huaihe and Haihe River basins
and northeast China, where the irrigation requirement index (crop water requirement met by irrigation)
may be as high as 50% or even higher in a dry year. The rice irrigation zone covers the middle and lower
reaches of the Yangtze River, the Pearl and Minjiang River basins and part of southwest China.
Chemical fertilizers and irrigation are usually the main measures to enhance agricultural production.
The use of fertilizer has reached its maximum in China and further increases will not affect the production.
Increase in the area of irrigation will be the main strategy to enhance agricultural production. China is
planning to increase the area of irrigation by 83%-122% in 50 years. Table 1.4 shows the projection of
the development of irrigation areas in the main river basins.
1.2.7.3 Inland Navigation
The cost of inland navigation is usually only 1/3 of railway and 1/10 of highway costs. The Yangtze
River, the Huaihe River, the Grand Canal, and the Pearl River are the main inland navigation channels of
China. In the Yangtze River and its tributaries the total length of navigation channels is 70,000 km, the
value is 20,000 km in the Huaihe River, 1,035 km in the Grand Canal, and 14,100 km in the Pearl River.
Nevertheless, the length of channel with water depth over 2.5 m, in which a 1,000 ship may navigate, is
less than 5,000 km. Canalization of rivers, construction of harbors and ship locks, and digging canals will
promote inland navigation.
1.2.8 Ecological Restoration and Integrated River Management
Environment protection and ecological restoration have become very popular in China. Restoration of
the impaired stream ecosystem is necessary for most of the worldrivers. Ecological restoration involves
the return of a given ecosystem to a state approximating that in which it existed prior to disturbances and
ecology protection implies maintaining the organisms and their environment unchanged.
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