Flood Risks Are Higher in Norther Portion of United States of America
A new study revealed that the risk of flooding is projected to be higher in the northern half of the US. Terrestrial and satellite data both show the flood threats growing.
Why is this happening?
The University of Iowa engineers who conducted the study have interesting answers to this finding.
The engineers found that the northern sections of the country in general have an increased amount of water stored in the ground. Because of this, this northern states are at greater risk for minor and moderate flooding, two flood categories used by the National Weather Service.
What about the other part of the United States?
Lucky for those who reside in the southern part, the engineers discovered that threats of flooding is low in these area including the American Southwest and West.
These findings are based on the records compiled water-height information between 1985 and 2015 from 2,042 stream gauges operated by the U.S. Geological Survey. The UI engineers then compared the data to satellite information gathered over more than a dozen years by NASA’s Gravity Recovery and Climate Experiment (GRACE) mission showing “basin wetness,” or the amount of water stored in the ground.
Other Relevant Findings
The study also pointed out that flooding in the United States is changing regionally, and the reasons could be shifting rainfall patterns and the amount of water in the ground.
According to UI engineer Gabriele Villarini, one reason why the northern part of the US has higher risk of flooding is attributed to changes in rainfall.
In a study published by Villarini published last year, it showed the Midwest and Plains states have experienced more frequent heavy rains in the past half-century. More rainfall leads to more groundwater, a “higher water base line.”
Aside from that, Louise Slater, also a UI engineer, said, “The river basins have a memory. So, if a river basin is getting wetter, in the Midwest for example, your flood risk is also probably increasing because there’s more water in the system.”
For the Southern part of the US which will be experiencing minor to moderate flood risk, Villarini explained that it is due to declining stored water. The NASA data showed decreased stored water-and reduced flood risk-in the Southwest and western U.S., in large part. This is due to the prolonged drought gripping these regions.
The National Science Foundation, through a CAREER grant to Villarini, the U.S. Army Corps of Engineers Institute for Water Resources, the Iowa Flood Center, and IIHR-Hydroscience and Engineering supported this research.