River conservation in central and eastern Asia
L. Li, C. Liu and H. Mou
This chapter reviews policy and practice of river conservation in central and eastern Asia (Figure 10.1). The area includes 10 countries but, geographically, is dominated by China which has 60% of the area and over 80% of the population. The other countries are Japan, the Democratic People’s Republic of Korea (North Korea), the Republic of Korea (South Korea), Mongolia, Kazakhstan, Uzbekistan, Kirghizia, Tajikistan and Turkmenistan. The total area of the region is 15 748 500 km2 with an overall population density of 93.5 persons km−2 (Table 10.1).
It is a region of political, demographic and environmental contrasts. In terms of topography, Mongolia, Kirghizia and Tajikistan are mountainous countries. Mongolia has an average elevation of 1600 m a.s.l. and 50% of Tajikistan and 30% of Kirghizia are higher than 3000 m. In contrast, eastern China is dominated by the Great Plain of China comprising the North China Plain, the Songlen Plain, the Yangtze River delta, and the Pearl River delta — in total, an area of about 3 × 106 km2. In terms of climate, the extensive Gobi Desert which forms over 30% of Mongolia contrasts with the East Asia Monsoon area where, for example, annual rainfall of more than 3000 mm characterizes southern Japan. With regard to population density, Japan is a highly urbanized country with half of the population concentrated in three large cities: Tokyo, Osaka and Nagoya. Kazakhstan and Turkmenistan have sparse rural populations, with densities of less than 7.5 persons km−2. Within China the majority of the population is in the plain and delta areas in the eastern part of the country. There are also different political and economic systems: central government and socialist political systems in Mongolia and North Korea, capitalist systems with market economies in Japan and South Korea.
With regard to biodiversity, China alone has more than 10% of the global species. The reasons for this include its large area, marked variations in climate and geographical conditions, and geologically stable land mass. The major ecosystems in China are divided into six groups (Mackinnon and Wang, 1996): (1) temperate and tropical forests (10%); (2) mountain grasslands (60%); (3) pasture and desert (15%); (4) main river corridors, lakes and wetlands; (5) wide seashore area and (6) agricultural land (11%). River corridors are particularly rich in biodiversity. The Yangtze River is the richest one in China; the number of fish species increases with catchment area and with river run—off depth and river gradient, and decreases with latitude (Shoukun, 1997).
Yet many species are under threat. For example, the Yangtze sturgeon (Acipenser dabryanus), Chinese river dolphin (Lipotes vexillifer) and Chinese alligator (Alligator sinensis) have become endangered because of habitat degradation, fishing pressure and accidents caused by river traffic and hydropower generation (see Dudgeon, 1992, for review). Habitats under threat include the huge lateral lakes of the Yangtze floodplain which are important wintering grounds for the rare white and black storks (Ciconia ciconia and C. nigro) and 98% of the world population of the endangered Siberian white crane (Grus leucogeranus) (Zhao et al., 1990). Mountain brooks at altitudes above 1000 m in central and south—west China are also under threat and the giant salamander (Andrias davidianus) is now endangered because of intensive hunting (Dudgeon, 1992).
Global Perspectives on River Conservation: Science. Policy and Practice.
Edited by P.J. Boon, B.R. Davies and G.E. Petts. © 2000 John Wiley & Sons Ltd.