By Lauren Haworth, LEED AP BD+C
Most people are familiar with the law of unintended consequences: fixing Problem A leads to Problem B, and sometimes a host of other problems as well. For decades, the standard approach to stream management has been an excellent example of this. For the most part, erosion and flooding issues have been treated using hard infrastructure solutions such as channelizing streams or constructing concrete dams and weirs. Unfortunately, these solutions often create other problems, such as reduced water quality, decreased wildlife habitat, and higher water velocities. Such solutions also often move erosion problems downstream rather than solve them.
Streambank restoration seeks to undo this damage by returning waterways to their more natural state. It can be as simple as removing a concrete weir or as complex as designing a new wetland. The goals are often to protect property and infrastructure by slowing stream velocities, improving water quality, providing habitat for fish and other wildlife, and reducing erosion and downstream sedimentation.
Many cities have engaged in restoration projects to revitalize rivers flowing through urban areas, enhancing the environment for both wildlife and people while still providing necessary flood control.
Many cities have engaged in restoration projects to revitalize rivers flowing through urban areas, enhancing the environment for both wildlife and people while still providing necessary flood control. Examples of such projects include California’s Los Angeles River, Colorado’s Platte River in Denver, and Arizona’s Rio Salado in Phoenix.
The City of Richardson, Texas was experiencing erosion issues along Duck Creek in a much-used neighborhood greenbelt. The stream had several concrete drop structures in place to slow flow and create ponds, but unfortunately, scour around the structures from flows during high-volume rainfall events had rendered them unsightly and susceptible to failure.
The solution: new, stone-faced drop structures replaced their concrete counterparts and although functioning similarly to its predecessor, the new design controls erosion more effectively and provides a more natural appearance. Instead of armoring the surrounding slopes with more concrete, the restoration employed turf reinforcing mat to lessen erosion and encourage native grasses to take root. Along with controlling erosion, these native grasses and adaptive plants provide habitat for the ducks that give Duck Creek its name.
With proper design, streambank restoration can render significant benefits in terms of safety and sustainability for people, flora, and fauna alike. Applying these natural, erosion-correcting techniques helps reverse prior damage, enhances the environment, and better manages storm water to prevent costly and dangerous flooding.