New Internationalist Issue 273
While delivering electricity - and to some degree controlling flooding - the 'conquest of nature' approach to river-engineering creates as many problems as it solves
Straightening out and diking rivers increases the speed and volume of the river's flow creating serious flooding in very wet years when dikes might not hold. Deforestation increases damaging erosion and destroys a river's watershed.
Silt is trapped behind dams, reducing fertility downstream as well as the capacity and life-span of the dam. Downstream silt must be replaced by expensive chemical fertilizer.
Dams always carry the danger of collapse due to earthquakes, flooding or sabotage. Casualties from dam collapse will be much higher than those from normal flooding.
Silt is trapped behind dams, reducing fertility downstream as well as the capacity and life-span of the dam. Downstream silt must be replaced by expensive chemical fertilizer. Riverine fisheries are destroyed as nutrients (fish food) become trapped behind dams and fish are unable to move up rivers to spawn. Downstream agriculture, with reduced water and silt flow, is subject to much higher dangers of salination (salt-poisoning).
Reservoirs flood the often-fertile land at the bottom of valleys and displace thousands of people to less suitable land or overcrowded urban areas. Large reservoirs, particularly in hot climates, have enormous losses of precious water through evaporation. Irrigation channels spread disease, particularly malaria (300 million sufferers) and bilharzia (200 million affected).
Diking cuts off wetlands which are natural absorbers of flood and provide a wildlife habitat.
©Copyright: New Internationalist 1995