Vermont ecologist urges protecting river corridors and riparian areas to improve flood resilience

Corinna Daly, restoration ecologist with the Vermont Natural Resources Council, told attendees Jan. 22 at the Center of Natural Resources & Energy that protecting river corridors and riparian areas gives rivers the space they need to move, slows flood waters and supports water quality.

"For the record, again, I'm Corinna Daly, restoration ecologist with Vermont Natural Resources Council," Daly said, introducing a slide presentation on river corridors and saying she would "pass it over to Laura Oates to talk a little bit more about the Flood Safety Act."

Daly defined a river corridor as the area adjacent to a river that must be kept free or managed so the river can move over time; she described the corridor’s width as the river’s "meander belt." She said the meander belt and river sinuosity reflect a river’s natural tendency to seek a less erosive path and that giving rivers space to move ultimately produces more stable, sinuous channels after periods of historical alteration such as dredging.

Daly framed river function in four dimensions. She said rivers have a lateral dimension — the ability to access their floodplain — that allows rivers to "jump out onto that floodplain and slow down" during high flows; a longitudinal dimension that moves water, sediment and nutrients downstream and allows aquatic organisms to move; a vertical dimension that connects surface water to groundwater and keeps streams cold; and a temporal dimension, because "rivers change over time." She said interventions such as dams or undersized culverts can block longitudinal connectivity and create ponds that raise river elevation and reduce access to floodplains.

"Rivers are not 1 dimensional. They exist in 4 dimensions," Daly said in the presentation. She identified consequences when those dimensions are interrupted: slowed water, warmer temperatures, lower dissolved oxygen and altered species composition — for example, ponds behind dams support warm-water species such as bass or sunfish instead of Vermont’s characteristic cold-water brook trout.

Daly noted the Vermont Climate Action Plan, the State Hazard Mitigation Plan, the Lake Champlain TMDL and the governor’s flood resilience implementation plan all recommend promoting connected river corridors, floodplains and wetlands and protecting the adaptive capacity of natural systems. She described riparian forest and vegetation as important for shading water, recruiting large woody debris that forms habitat, filtering sediment and nutrients, and stabilizing banks.

Daly used a historical example of dredging to illustrate recovery when dredging stops: she referenced a river dredged in 1924 and said that when dredging ceased, the river returned over time to a more sinuous path. She emphasized nature-based solutions — protecting river corridors and connected freshwater systems at watershed scale — as a primary strategy to build flood-resilient communities by slowing and attenuating stormwater and reducing economic and public-safety burdens.

Daly concluded by saying she would hand the presentation to Laura Oates to address the Flood Safety Act; the excerpted portion of the meeting contained no formal motions or votes related to the topic.