environment + Sustainability
River engineering impacts
Study indicates that human-engineered changes on the Mississippi River have increased extreme floods.
The research team sampled bottom sediments from three lakes along the lower Mississippi River in Mississippi and Louisiana: Lake Saint John, Lake Mary, and False River. Large floods spill sediments and organic debris from the river into adjacent lakes. They form telltale layers of larger particles and material on the lake bottoms that scientists can use to trace the history of flooding back over hundreds of years.WHOI paleoclimatologist Jeff Donnelly pioneered this coring technique in the coastal ocean to trace the history of hurricanes. Image: modified from Munoz et al. 2018
A new study has revealed for the first time the last 500-year flood history of the Mississippi River. It shows a dramatic rise in the size and frequency of extreme floods during the last century —mostly due to projects to straighten, channelize, and bound the river with artificial levees. The new research, led by scientists at Woods Hole Oceanographic Institution (WHOI), also uncovered a clear pattern over the centuries linking flooding on the Mississippi River with natural fluctuations of Pacific and Atlantic Ocean water temperatures. This newly recovered long-term record provides a historical context that spotlights how more recent river engi- neering has intensified flooding to unprecedented levels. “The floods that we’ve had over the last century are bigger than anything we’ve seen in the last 500 years,” said Sam Muñoz, Ph.D., a former postdoctoral scholar at WHOI and the lead
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csengineermag.com
june 2018
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