Human Activity Causing Deltas to Sink

One of the deltas in danger is the Irrawaddy River delta in Burma (Myanmar). The image above is an elevation map, made from data collected by the Shuttle Radar Topography Mission.

Researchers have warned that two-thirds of the world’s deltas are sinking, putting tens of millions of people at risk. And it appears human activity is at fault.

A report by a team led by University of Colorado-Boulder professor James Syvitsky reveals that 24 of the world’s 33 major deltas from Asia to the Americas are becoming more vulnerable to flooding from rivers and ocean storms due to sinking land and rising seas.

Damming and diversion of rivers for agriculture and other uses upstream are holding back sediment that would normally build up in the deltas, replacing what is lost by erosion.

And climate change due to greenhouse gases is causing sea levels to rise around the planet.

The report’s authors predict that global delta flooding could increase by 50 percent under one projection of about 18 inches in sea level rise by the end of the century.

That’s the level of rise projected by the 2007 Intergovernmental Panel on Climate Change report.

The report on delta subsidence was published in the journal Nature Geoscience.

Photo: NASA Earth Observatory