全世界小型水库有80多万座,大型水库有4万多座,特大型水库有300多座。20世纪90年代全世界水电年发电量达2万亿度,据世界能源理事会的估计到2020年可增加到5万亿度。长期以来,人们靠修建大坝控制洪涝灾害,提供生活用水、工业用水和农田灌溉。从发电来说,与火电相比,水电确实具有管理成本低、运营简单等优点。但是水坝建设给人类社会和环境带来的一些不良影响,甚至是灾害,也应引起人们广泛的关注。———编者 There are more than 800,000 small reservoirs worldwide, over 40,000 large reservoirs and over 300 large reservoirs. In the 1990s, the annual hydropower generation in the world amounted to 2 trillion kWh, which, according to the World Energy Council, is estimated to increase to 5 trillion kWh by 2020. For a long time people rely on dams to control floods and provide domestic water, industrial water and farmland irrigation. In terms of power generation, compared with thermal power, hydropower does have the advantages of low management cost and simple operation. However, some adverse effects caused by dam construction to human society and the environment, even disasters, should also cause widespread concern. ---editor