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
The World Bank's New Policy on the Environmental Aspects of Dam and Reservoir Projects ∗
THE SUSTAINABILITY of economic development has recently become one of the top .most priorities of.the World Bank. The Bank seeks to promote sustainability in all relevant projects and sectors. The most influential way in which sustainability can be approached is to ensure that all environmental and natural resources implications are integrated into Bank work at all stages. This· article outlines the Bank's most recent progress in this regard. Parallelling this policy, the Bank is exploring the implications of the concept of sustainability itself, and Herman Daly has started to operationalisc sustainability1• The basic assumption is that.much of the developing world needs more energy. A westerner ·uses fuels and electricity at the rate of about 10 kilow~tts, whereas a Chinese uses about one kilowatt, and many people use much less2• Only by using more energy can standards of living of the poorest rise to acceptable levels. Irrigation pumps are a case in point. Concern with big dams and reservoirs amply detailed in Goldsmith and Hildyard's most useful compilation ~. is understandable, and this policy focuses how such concerns can be mitigated. Concern with big dams -and reservoirs is a subset of the broader questions of how to feed and supply with energy the one billion extra people projected to swell the world's already too large population every decade. Specifically, how can hunger be averted, how can shortages of water and power also be averted? The answer lies in three areas, first population control, second conservation of water, and third, conservation of energy. 1. Rapid Popul.ation Control Food and energy supplies will be eased to the extent population growth rates fall. Population control is the nm qua non of sustainability. The catch-up race to supply food, water and energy to the world's burgeoning population is a race ·between arithmetic progression and geometric progression, and is related to most of the world's pervasiive negative externalities, such as acid rain, the greenhowe problem, irreversible .loss of biodiversity, and of topsoil. Within my lifetime, the world's population is rushing from two to 10 billion and is already halfway there. The·sooner the race is called off by successful family planning, the sooner will be tbe world's overdue transition to sustainability.
Design of reinforced concrete lining in pressure tunnels, considering thermal effects and jointed rockmass
Abstract Jaeger's theory (Jaeger, Rock Mechanics and Rock Engineering , Cambridge University Press, 1972) of the design of the lining for a pressure tunnel applies to a tunnel located in an isotropic, homogeneous and elastic medium. The theory is derived from the elasticity equations for the plane stress condition. In this paper, Jaeger's theory is extended to a plane strain situation. Also included is a discussion of the effects of a uniform increase (or decrease) in the lining temperature, jointed rockmass, cracking of the tunnel lining, and cracking of the rockmass around the opening. Tables are presented for the modulus of subgrade reaction for various rockmass conditions and for rock sharing pressures for various lining conditions. The reduction factor to include the effect of joints in rockmass is derived by the analysis of a numerical model of the lined tunnel by the finite-infinite-interface element method.