Assessment of the environment effects of constructing the Three Gorge Project on the Yangtze River
The Three Gorge Project is a multipurpose project with the primary function of flood control. Other functions include power and navigation and could include irrigation. A 200 m high concrete gravity dam, currently being considered, would be located in the lower reach of the famous Three Gorges of the Yangtze River in Hubei and Sichuan Provinces. The reservoir will store about 70 x 10 to the 9th cu m and extend upstream about 780 km. The proposed powerplant would have an installed capacity of 25,000 MW, consisting of twenty-five 1000-MW units. The Three Gorge Project, when constructed, would be the largest water resource project anywhere on earth. Beneficial effects include elimination of flooding along the middle and lower reaches of the Yangtze River, a substantial increase in much needed electric power for south and central China, and creation of a large body of water which could be used for aquaculture. Consideration is also being given to diverting water to the North China Plain, one of the most important agricultural areas of China. Major adverse impacts include relocation of more than 2 million people for the reservoir area; loss of habitat for many kinds of Yangtze River aquatic life, including themore » unique Chinese sturgeon; and the possibility of reducing nutrient input to the downstream and estuarine fisheries. The possibility of minimizing adverse effects seems high, if the potential environmental impacts are identified and means of mitigation are carried out. 22 references, 1 figure.« less
River regulation in Southern China: Ecological implications, conservation and environmental management
Southern China—i.e. China south of the Chang Jiang (Yangtze River)—has a monsoon climate with pronounced wet and dry seasons and consequent effects on river discharge. There is considerable inter-year variation in the duration and intensity of the monsoon, and the region experiences frequent floods and droughts which cause considerable human misery. The importance of floods as an incentive for river regulation is apparent from the fact that 10% of China's area, inhabited by 65% of the population and responsible for 70% of the agricultural and industrial output, is below the flood level of major rivers. Irrigation and hydroelectric power are additional benefits to be derived from river regulation. China has a 4000 year history of river regulation, but most of the changes that have been made to riverine environments have not taken account of the ecological consequences. This review considers the ecological implications of planned or existing schemes for the regulation of southern Chinese rivers. Particular attention is paid to the Chang Jiang and Zhujiang (Pearl River) which, by volume of discharge, are the two largest rivers in China. Large-scale water-transfer projects and the planned construction of the biggest dam in the world (the Three Gorges High Dam) on the Chang Jiang have the potential to affect fisheries stocks and endangered fish species, to alter inundation patterns in wetlands of international conservation significance and may contribute to the extinction of the endemic and highly endangered Chinese alligator (Alligator sinensis) and Chinese river dolphin (Lipotes vexillifer). In addition, deforestation and soil erosion in the Chang Jiang basin have given rise to siltation and degradation of floodplain habitats. In the Zhujiang, dam construction has caused reductions in fisheries stocks but here, as elsewhere in China, the ecologically damaging consequences of river regulation are exacerbated by overfishing and increasing pollution of rivers by sewage, pesticides and industrial wastes.
Heat Recovery Systems
Geothermal energy is recovered from an underground zone of relatively hot strata via a borehole into which is inserted a heat pipe system containing a working fluid, the heat pipe system comprising an assembly of two tubes in concentric relation, the inner tube being constituted by a relatively small diameter capillary for the return of working fluid to the vicinity of the zone of the relatively hot strata. The working fluid is preferably assisted in its return under gravity by means of a pump. The system includes heat exchange means operable to recover thermal energy from the working fluid. A third and outermost tube may be used to reduce heat losses, this third tube enclosing the two tubes over all but that part of their length which is in the zone of relatively hot strata.