By Lloyd George.
A large dam 700 feet high and holding back a vast expanse of water is a breathtaking spectacle. While they always feature on lists of modern engineering wonders, the impact of dams is always far more than visual.
They are found, large and small, on every continent, on 60% of the world's rivers, and often perceived benefits are outweighed by the repercussions they cause downstream.
They contribute to over 15% of world food production and provide 40% of all artificial irrigation.
Almost 20% of world electricity production is derived from this source. In 1950 there were just 5000 dams in the world over 50 feet in height whereas today (2013) there are over 54,000.
Problems caused by dams can be experienced up to 1,250 miles downstream.
Frogs, fish, turtles and crocodiles along with more exotic creatures such as fresh water dolphins have become extinct, and salmon populations decimated.
Rural communities have been eradicated and whole nations displaced. Many dams are in remote areas whose people have distinct social and cultural identities.
80 million people have been displaced from their homes by dam construction in the 30 years prior to 2005. Since then a further 20 million Chinese and 10 million Indians have been displaced.
Another estimated 800 million people have been adversely affected by changes in river flows and ecosystems in the last 40 years.
Done properly hydro power can make an important contribution to an energy poor community, but if you leave the downstream river dry or with a constant flow - something that is unnatural to that particular environment - you destroy people and their culture.
China has already constructed 5 giant dams along the upper reaches of the 3000 mile long Mekong while 11 more are planned further down in Laos and Cambodia.
Sixty million people rely on the lower Mekong for their livelihood. These dams will slow the movement of sediment downstream which will adversely affect rice farmers in the Vietnamese delta.
Forest communities that fish and grow crops will be inundated by these dams.
China is currently building 312 dams over 50 feet in height in 72 different countries.
Most Chinese hydro power companies build dams that have catastrophic outcomes for the communities they are constructed for. There is no controlling body for dams, which means a profit free for all bonanza for irresponsible construction companies.
While we are trying to protect our own environment, our own corner of the world, big business is destroying the rest of the world.
Vigilance of the world around us and political pressure brought to bear on ecological terrorists such as China, is extremely important if we are to retain a green and pleasant land for our children to inherit.