Lecture 4: Water and energy Flashcards
Dams : facts and figures
About half of the global 48 000 large dams are in China.
Another 1,600 large dams are under construction worldwide in an industry whose annual turnover is estimated at $50 billion or more.
China, Turkey, Iran, and Japan account for 67% of the total number of dams under construction worldwide in 2003.
Half the world’s large dams were built for irrigation. Some 30-40% of the 271 million hectares irrigated worldwide rely on dams
Of the world’s 227 largest rivers, 60% are severely fragmented by dams, diversions, and canals, leading to the degradation of ecosystems
An estimated 40-80 million people have been displaced from their homes by dam construction.
The annual expenditure on large dams during the 1990s was between $32 and $46 billion. Throughout the twentieth century some $2 trillion was spent on dams.
6000 of the major global dams
Vary in size and geographical distribution
Much more common in developed world
Capacity now growing rapidly in less developed world
Growth has been very rapid
Surface water detention in dams
21% of the global land area drains into a dam
Few rivers unaffected by them - they change flow regimes and prevent migration of species.
Threaten freshwater biodiversity.
