Environmental Engineering Reference
In-Depth Information
the country, which consists of 42% of the total moisture inflow and the main moisture outflow is across
the east border, which is 60% of the total outflow. Therefore, the main moisture flow path over China is
from the south border to the east border, which makes the southeasten China wet. Only 10%-23% of the
moisture inflow and outflow are across the west and north borders. Thus, the precipitation in north and
west China is much less than in south and east China. The average precipitation in the southeast of China
is about 2,000 mm, and the highest precipitation takes place at the China-India boundary, which is about
5,000 mm. In the zone south of the Yangtze River the precipitation is about 1,000 mm. In the zone from
the Yangtze River to Qingling and the lower Yellow River, it is about 800-900 mm. Further to the north the
precipitation reduces to 400-600 mm. precipitation is even less to the northwest. The lowest precipitation
occurs in the Turpan basin with average annual rainfall of only 7.1 mm. The reason to make the water
resources availability even worse is the non-uniform distribution of rainfall over time. In south China the
maximum 4 month precipitation is about 60% of the annual precipitation while in north China the value
is 80%. The inter-year variation, defined as the maximum annual precipitation over the minimum annual
precipitation is larger than 8 in the northwestern China, 3-4 northeastern china and 2-3 south China.
The surface runoff is mainly transported in the 7 major rivers listed in Table 1.3. In the Pearl River basin
the water resources per capita is more than 4000 m
3
, but the value is only 260 m
3
in the Haihe-Luanhe
River basin.
Table 1.3
Water resources of major rivers in China and comparison with the world average (after Chen, 1991)
Runoff
(10
9
m
3
)
Population
(million)
Farmland
(10
6
ha)
Water/p
(m
3
/p)
Water/ha
(m
3
/ha)
River basin
Pearl River
336
83
4.7
4,097
71,670
Yangtze River
951
380
23.4
2,505
40,575
Songhua River
74
52
10.4
1,451
7,110
Yellow River
66
93
12.2
716
5,430
Huaihe River
62
142
12.3
439
5,055
Liaohe River
15
34
4.4
435
3,345
Haihe-Luanhe Rivers
29
110
11.3
262
2,550
World average (1987)*
38,830
5,000
1,500
7,766
25,887
World average (1996)*
38,830
5,770
1,500
6,730
25,887
World average (2006)*
38,830
6,480
1,500
5,995
25,887
Note: The total ground water of China is 872 billion m
3
;
* Data source: the Ministry of Water Resources of China.
The development of the economy and urbanization has been increasing the water demand very quickly
in the past two decades. The number of cities in China increased from 295 in 1984 to 640 in 1995, in the
same period the urban population increased from 140 to 400 million. The water consumption per person
also increases quickly following the enhancement of the living standards. For the last twenty years, the
rapid expansion in urban water supply systems has been evident, both in terms of the increase in the
number of urban systems and cities served and in the water supplied for both residential and industrial
purposes. In 1996, 95% of the non-agricultural residents living within city boundaries were connected to
an urban system, with coverage falling to 85% in the northeast provinces of Heilongjiang, Jilin and Inner
Mongolia. However, only 25% of the agricultural residents in the areas defined as urban are served by
water systems.
The Water Law of the People's Republic of China stipulates that: “in the development and utilization
of water resources, the domestic water demands of urban and rural inhabitants shall be satisfied first,
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