Protect the world's deltas

摘要

More than a century after Mark Twain argued that the Mississippi River could never be tamed by engineers, dams and dikes constrain the great waterway. Its once muddy waters run clearer. Starved of sediment and fragmented by economic development, the Mississippi delta downstream is shrinking by thousands of hectares per year. The rich delta ecosystem and the services it provides - storm protection, nutrient and pollution removal and carbon storage-are being destroyed. Fisheries and the bayou cultural heritage are threatened. Deltas worldwide share this fate. In Pakistan, one-fifth of the Indus delta plain has been eroded since the river was first dammed in 1932. In China, the northern shore of the Yellow River delta has retreated 300 metres each year for the past 35 years.