Study: Humans caused river flooding

Through discovery of ancient floods along the Mississippi River, a group of scientists found that human-led engineering, not climate, was the largest influence on worsening floods. The group included Dr. Matthew Therrell, a University of Alabama geography professor and co-author of the report, which was recently published in the journal Nature, concluded that the interaction of human alterations to the Mississippi River system with dynamical modes of climate variability has elevated the current flood hazard to levels that are unprecedented within the past five centuries. Large floods during this and the 20th century were put into context when researchers used sediment cores and tree rings to extend flood records 500 years. The team found the magnitude of the 100-year flood is 20 percent greater now than 500 years ago, with river engineering accounting for 75 percent of the increase. Human alterations to the Mississippi River, with assistance from climate variability, have exacerbated current flood risk to unprecedented levels. (Source: University of Alabama 05/09/18)