Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 47-7
Presentation Time: 10:15 AM


FIELD, John J., Field Geology Services, P.O. Box 824, Portland, ME 04104

For decades New England streams were straightened, bermed, simplified, and otherwise “cleaned” to remove boulders, wood, and other obstructions meant to aid the passage of logs, sediment, and floodwaters. Channel adjustments in response to these past manipulations continue to this day and often result in damaging and life-threatening hazards associated with the rapid sediment infilling of channels, reformation of meanders, reestablishment of complex channel patterns, and reconnection to previously blocked floodplains. Resilient streams, in contrast, are a “mess” that experience few morphological adjustments during floods. The “mess” that enables resilient streams to withstand dramatic changes in channel dimensions and planform consists of wood, boulders, and other structural elements within the channel that slow the passage of floodwaters, prevent sediment from concentrating in a single area, and enhance ecosystem complexity. The targeted restoration of previously straightened and manipulated streams in New England by creating a “mess” through the addition of wood and boulders to the channel can increase the stream’s resiliency to withstand the rapid changes that result in property damage and loss of life. While the addition of wood and boulders in developed areas could potentially increase risk, strategically located restoration efforts safely distanced from human infrastructure can attenuate the stream’s energy and sediment load and thus increase stream resilience to rapid change in areas even beyond the limits of restoration. Identifying where “messy” natural channel processes can be safely restored on previously altered stream systems can reduce costly flood damages while simultaneously improving ecosystem resilience to future changes.