In brief

摘要

At least a quarter of the sediment carried in the world's rivers is being trapped behind dams instead of reaching the oceans, according to an international team of water resource analysts. They warn that taking so much sediment out of circulation could have significant effects on coastal ecosystems. The World Commission on Dams has previously estimated that sediment fills between 0.5 and 1 per cent of reservoir capacity each year. Now a team led by Charles Voeroesmarty of the water systems analysis group at the University of New Hampshire, Durham, has calculated how much sediment is involved.