Tuesday 22 September 2009

River deltas sinking across the globe except in Australia and Antarctica?


A study was published in Nature Geoscience this month on the vulnerability of river deltas and finally there was some guarded good news for Australia in relation to flooding and rising sea levels.

Many of the world's largest deltas are densely populated and heavily farmed. Yet many of their inhabitants are becoming increasingly vulnerable to flooding and conversions of their land to open ocean. The vulnerability is a result of sediment compaction from the removal of oil, gas and water from the delta's underlying sediments, the trapping of sediment in reservoirs upstream and floodplain engineering in combination with rising global sea level. Here we present an assessment of 33 deltas chosen to represent the world's deltas. We find that in the past decade, 85% of the deltas experienced severe flooding, resulting in the temporary submergence of 260,000 km2. We conservatively estimate that the delta surface area vulnerable to flooding could increase by 50% under the current projected values for sea-level rise in the twenty-first century. This figure could increase if the capture of sediment upstream persists and continues to prevent the growth and buffering of the deltas.

Worst hit will be Asia, but heavily populated and farmed deltas on every continent except Australia and Antarctica are in peril, it says according to SBS World News.

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