Global warming has caused tremendous effects on much of the world's waters including river deltas. More than two-thirds of the world's 33 major river deltas are sinking, scientists warn.
Sinking and flooding of deltas are seen as a result of human activity, a new study by University of Colorado Boulder researchers says. These wetlands are continually getting damaged, brought about by climate change and human actions.
The researchers race to shed light on what might have caused the sudden degradation of some of the world's most important river deltas, including the Yellow River in China and the Mississippi River in Louisiana. This valuable information could help scientists determine ways to mitigate the shrinking of these important bodies of water.
"These deltas are starved of the sediments they need for stability because of upstream dams that trap the material," said James Syvitski, a professor in geological sciences in UC Boulder.
"We are seeing coastal erosion increasing in many places across the planet," he added.
What Are River Deltas?
A river delta is a low-lying landform that is found at the mouth of a river where it flows into another body of water like oceans. When a river reaches a lake or an ocean, the water slows down and loses its power to carry sediment. The sediment accumulates at the mouth of the river.
In some rivers, there's so much sediment that it builds in layers forming a delta. Some deltas are so large and vast that people can live on them. Deltas are important to both wildlife like fishes and humans because they are home to very fertile soil and vegetation.
River Deltas Are Sinking
"Deltas are sinking at a much greater rate than sea levels are rising," Syvitski said.
River deltas are affected by human acts including extracting groundwater and fossil fuels, engineering river channels, trapping sediments behind dams and the reduction of water flowing into rivers. In some areas, the land is sinking by 10 inches per year. In four years, the land can sink by about 3 feet, making it prone to storm surges, hurricanes, tsunamis and flooding.
Why Are River Deltas Important?
River deltas have been important to humans for thousands of years. At present, they are still important since they provide a good source of sand and gravel. These materials are very important in the construction of infrastructures like highways and buildings. About 500 million people live on river deltas across the globe and that number have been increasing.
In agriculture, deltas provide fertile soil where humans can grow vegetation. For instance, Sacramento-San Joaquin Delta in California, is one of the most productive state in terms of agriculture.
For wildlife, deltas are vital for biodiversity. It is important that deltas remain healthy to provide habitat for a lot of species of plants and animals. Deltas also provide protection and buffer for hurricanes that threaten both humans and ecosystems.
Photo: Kin Lane | Flickr
