In the absence of beavers and their dams to slow stream velocities, many North America streams became badly eroded, incised and damaged. As erosion cuts a stream channel deeper and deeper into the ground, the surrounding water table also drops. Once the water table drops too low for the roots of nearby plants to reach, the lush native vegetation dies off resulting in a barren, arid landscape with a loss of biodiversity. A once vibrant area can become a desolate dust bowl, all due to stream incision.
It is well known that beaver dams heal the damage of stream incision. Unfortunately some streams are so badly incised that they are inhospitable to beaver and other wildlife due to steep banks and the loss of nearby vegetation. In recent years though, an innovative stream restoration technique is changing this dynamic. Research has proven that Beaver Dam Analogs (BDA) combat stream incision by promoting sediment deposition. The sediment deposition process from BDA’s has been surprisingly quick.
Similar to natural beaver dams, BDA’s slow water velocity, allowing suspended particles to settle. As sediment accumulates the stream bottom rises, resulting in corresponding elevations of the surrounding water table. Stream banks become less steep and the stream once again becomes hydrologically connected to the floodplain. With higher ground water native shrubs and trees begin to return, which will then attract beavers. Beavers continue the stream restoration process by building their own dams, often on top of the BDA’s. The riparian corridor becomes a lush and healthy ecosystem that attracts all sorts of species. Biodiversity again flourishes, and the stream restoration process is successful.