Classifying floodplains: An innovative approach to flood mitigationby Hannah Fischer, University of VermontEast Montpelier in July of 2024. Cred...

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Classifying floodplains: An innovative approach to flood mitigationby Hannah Fischer, University of VermontEast Montpelier in July of 2024. Cred...
Classifying floodplains: An innovative approach to flood mitigation
by Hannah Fischer, University of Vermont

East Montpelier in July of 2024. Credit: Vermont Agency of Transportation
As extreme weather and flooding events become more intense and frequent due to climate change, improving flood mitigation strategies has never been more critical. The livelihood of downstream communities relies heavily on effective flood resilience measures to reduce flood levels and decrease the power of flood waters.

Floodplains—low-lying areas adjacent to rivers and streams—can play a crucial role in reducing flood impacts, helping to protect lives, agriculture, and infrastructure by influencing how water moves across the landscape. Acting as a natural buffer, floodplains temporarily store floodwater, reducing flood peaks and minimizing the erosional power, in a phenomenon called attenuation.

However, new research by the University of Vermont (UVM) shows that not all floodplains function in the same way. The study reveals that varying topographic features affect a floodplain's ability to ease flood water's momentum and impact.

Publishing their findings in the Journal of Geophysical Research: Earth Surface, the team introduces an innovative method to detect floodplains and classify them based on their ability to attenuate floods.

"This approach enables the assessment of floodplains and their processes across broad scales to better account for their functions and potential to contribute to flood resilience," said Dr. Rebecca Diehl, the study's lead researcher. "Floodplains typically aren't included in large-scale water resource assessments, such as flood prediction models, yet, they can play a significant role in routing floods across the landscape and determining the impacts of floods."

The study leverages widely available topographic datasets to identify features along the edge of the river channel that are hypothesized to slow floodwaters to a greater degree than the surrounding area. Floodplain settings were then grouped based on the presence, size, and shape of these features. When the research team evaluated the ability of each type of setting to store and slow floodwaters, they found distinct differences among them, demonstrating a clear relationship between flood routing and topography.

This process was demonstrated in the Lake Champlain Basin in Vermont, spanning elevations from 1,339 m to 29 m, through the steep gradients of the Green and Taconic Mountains to the lowlands of the Champlain and Hudson Valleys. The study revealed six distinct floodplain types present in the region, each playing a unique role in attenuating flooding.

The resulting concept, the Hydraulic Floodplain Classification, emphasizes the landscape's variable capacity to influence flood routing. While the initial study was conducted in the northeastern United States, the workflow and concepts proposed are transferable, allowing it to be applied to other regions and watersheds across the country, offering a versatile tool for water resource assessments and floodplain management applications.

Vermont was hit hard by floods in July of 2024. Credit: Vermont Agency of Transportation

Implications for watershed management and restoration
By pinpointing floodplains that are most effective at slowing floodwaters, the study provides valuable insights for restoration and conservation projects. Understanding which attributes have the greatest potential for attenuation can help guide watershed management by prioritizing sites for floodplain reconnection, infrastructure removal, or riparian revegetation, and guiding restoration design.
SOURCE:https://phys.org/news/2025-04-floodplains-approach-mitigation.html?utm_source=flipboard&utm_content=topic/environment

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