14 DAY TRIAL // Scientists at the University of Colorado in Boulder (UCB) have recently released a new report on the situation of deltas around the world, which states that their condition is deteriorating globally. Most at risk is the low-lying variety. Human “improvements” and development made around or on them render them more vulnerable to the effects of ocean storms or river flooding, in most cases. The experts say that tens of millions of people are at risk because of this situation, which is getting worse every year, ScienceDaily reports.
One of the most important factors in deltas' sinking is the fact that, on the largest rivers in the world, dams and levees are preventing important amounts of sediments from passing through, and being deposited by the waters where the river meets the sea. As a result, the deltas have no external sediment sources, and start being overrun by the ocean. These formations take millions of years to form at the mouth of a river, but can be covered up within a human life span.
“We argue that the world's low-lying deltas are increasingly vulnerable to flooding, either from their feeding rivers or from ocean storms. This study shows there are a host of human-induced factors that already cause deltas to sink much more rapidly than could be explained by sea level alone,” UCB Institute of Arctic and Alpine Research research associate Albert Kettner, who is also a member of the Community Surface Dynamic Modeling System (CSDMS) team, and a co-author of the new study, says.
“Every year, about 10 million people are being affected by storm surges. Hurricane Katrina may be the best example that stands out in the United States, but flooding in the Asian deltas of Irrawaddy in Myanmar and the Ganges-Brahmaputra in India and Bangladesh have recently claimed thousands of lives as well,” INSTAAR researcher Irina Overeem, also a co-author of the new study, adds. She is a CSDMS expert, and a scientist at UCB. A paper detailing the finds appears in the September 20th issue of the respected journal Nature Geoscience. The research was supported by a $4.2-million grant from the National Science Foundation (NSF).
“Although humans have largely mastered the everyday behavior of lowland rivers, they seem less able to deal with the fury of storm surges that can temporarily raise sea level by three to 10 meters (10 to 33 feet). It remains alarming how often deltas flood, whether from land or from sea, and the trend seems to be worsening,” the authors conclude.