Seite - 1013 - in Book of Full Papers - Symposium Hydro Engineering

cut off the link between rivers and bottomland or floodplains, limits the horizontal spread of water flow, and results in decrease in horizontal river connectivity and habitat loss for aquatic organisms. In addition, transforming rivers into channels and cutting off curves have completely changed the basic landform of meandering rivers, and the pattern in which rapid and slow flows alternate disappeared. The regular geometric changes on the cross-section also altered the pattern in which deep pools and shoal patches alternate. As the habitats heterogeneity was reduced, aquatic ecosystems were changed and biological diversity was reduced accordingly. This is embodied by shrinking areas of riverside vegetation and plants, reduced biodiversity in micro-habitats, altered spawning conditions for fish, changes in the habitats of birds, amphibians, and insects, or disappearance of shelters, which may lead to reduced populations and the extinction of some species. 6. EXISTING PROTECTIVE MEASURES FOR AQUATIC ECOSYSTEMS 6.1. LAWS AND REGULATIONS By 2005, 9 laws on the protection of the ecological environment and 15 laws on the protection of natural resources has enacted, and more than 660 regulations and local laws have enacted and passed. Seven fish species in the Yangtze River Basin are under national-level protection, the first-class protected animals Dabry's sturgeon, Chinese sturgeon, and Chinese paddlefish; the second-class protected animals huchobleekeri, Chinese high fin banded shark, trachidermusfasciatus, and anguillamarmorata (Law of the People's Republic of China on the Protection of Wildlife, 1989); 69 fish species are included in the China Species Red List at or above the endangered level; aquatic animals listed under first-class protection include Yangtze River Dolphin, finless porpoise, and bank beaver, giant salamander etc. are under second-class protection. 6.2. CONSERVATION AREAS AND ACHIEVEMENTS By 2004, 561 nature reserves have been established in the Yangtze River Basin, covering a total area of 32.88×104km2, accounting for 18.3% of the Basin area. Among them, 59 are state-level with an area of 22.89×104km2; 202 are provincial-level with an area of 6.44×104km2; 59 are aremunicipal-level with an area of 1.74×104km2; 241 are county-level nature reserves with an area of 1.81×104km2. Nature reserves are distributed along the upper reaches and the mainstream as well as at the mouths. So far, a network of diverse nature 1013