Wetland Loss can Impact Long-term Flood Risks

By: Ashley Rone

Wetlands are a crucial part of the natural environment that provide a habitat to animals and plants, improve water quality, and reduce flood potential. The loss of wetlands changes stream and river chemistry and can alter the way ecosystems function. The decrease in water leads to an increase in pollutants that are not filtered out and the water quality decreases. This reduced surface area of water leaves the land prone to flooding under heavy precipitation and snow build-up.
Research done on the loss of wetlands in North Dakota can provide valuable information about flooding potential and how to restore wetlands. One particular researcher at the University of North Dakota, Dr. Xiaodong Zhang, has focused on the Devils Lake water basin.

“North Dakota is part of pothole area in the U.S., and used to be covered with stretches of wetland,” said Dr. Zhang. “Draining wetland has certainly increased flooding potential in the region.”

He and his team of fellow scientists used the Soil and Water Assessment Tool (SWAT) hydrological model to identify water movement in the Devils Lake watershed area. Combined with data from the historical and Coupled Model Intercomparison Project Phase 5 (CMIP-5) they were able to estimate flood risks.
“Currently, 11% of the Devils Lake basin is covered by wetland. A 5% increase to 16% of wetland coverage would reduce the Devils Lake water level by approximately 0.5 m,” Zhang explained. “This is mainly because the presence of wetland reduces the peak stream flow.”

A figure taken from the research article published by Sergey Gulbin, Andrei P.Kirilenko, Gehendra Kharel, and Xiaodong Zhang called Wetland loss impact on long term flood risks in a closed watershed. Image A shows a map of the Devils Lake Basin and the Red River North basin boundaries. Image B shows the water level change of Devils Lake.



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A figure taken from the research article published by Sergey Gulbin, Andrei P.Kirilenko, Gehendra Kharel, and Xiaodong Zhang called
Wetland loss impact on long term flood risks in a closed watershed.
Image A shows a map of the Devils Lake Basin and the Red River North basin boundaries. Image B shows the water level change of Devils Lake.

Based on these predicted flood risks, the researchers examined potential solutions that would benefit the Devils Lake area in the future. “Operating the two outlets that have been built is more effective in controlling rising water of Devils Lake than restoring wetland,” said Zhang. “On the other hand, diverting water from Devils Lake to the Sheyenne River would increase the flooding potential of the river and degrade its water quality. So, there is no perfect solution.”
This information is useful for the state of North Dakota in terms of risk management and building river diversions that help prevent flooding. The next step in flood risk research is to approach state agencies with hopes that they will take the research findings into account in their future decision making.