Researchers Seek Input on Floodplain Map Uses and Potential Improvements

With summer and winter flooding during 2023 and 2024, communities across Vermont and the Lake Champlain basin are simultaneously rebuilding and planning for the next flooding event.

In 2022, researchers funded by Lake Champlain Sea Grant released maps illustrating how floods of varying sizes are expected to spread across river valley surfaces. Each color on these maps represents the potential extent of floodwaters for eight storm sizes, ranging from 2-year to 500-year flood probabilities.

These floodplain maps are designed for conservation planning and research by government agencies, academic institutions, commercial entities, and non-governmental organizations. They provide a broader geospatial coverage of floodplains in the basin compared to Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps. However, they are not intended as a replacement for FEMA maps and should not be used for regulatory purposes.

Dr. Rebecca Diehl and Dr. Kristen Underwood from the University of Vermont, who developed these maps, anticipated they would assist decision-makers at both state and municipal levels in evaluating the hazards associated with extreme flooding events in a changing climate and the opportunities to improve floodplain access for building flood resilience.

Now, more than two years later, we’re seeking input from stakeholders who use, or may be interested in using, these maps for multiple purposes. To better understand the role of these maps in climate resilience and conservation planning and solicit feedback, Diehl and Underwood have created a survey.

“With the survey we would like to ascertain the who and how, but also look to see if there are opportunities for improved communication about what the maps are and their appropriate utility,” said Diehl. “We also are planning on updating the maps with the most recent state-wide LiDAR data (collected in the Spring 2023) and improving our methodology to overcome shortcomings we are aware of. With these planned updates, we would like to incorporate feedback from stakeholders on what they are noticing in the maps or what they hope to see.”

If you have used these floodplain maps and have any insights to share, or are interested in learning more, please take a moment to complete the survey. For any questions about the survey or the floodplain maps, please contact seagrant [at] uvm.edu.