Repairing the necklace - restoration of urbanized stream channels; integrating habitat, aesthetics, recreation, and flood flow attenuation

Urban stream channel corridors often represent some of the last remaining contiguous blocks of wildlife habitat in heavily urbanized settings.  These corridors have often suffered insults due to urban encroachment, hydrologic modifications in the watershed, invasive species, and urban runoff.  At the same time they can offer the human population a rare opportunity to see urban open space in a more “natural” context and offer lessons on human perturbations in ecological systems.  Manipulation of these systems with an eye towards storm runoff control has drastically altered the ecological functioning of these systems and has caused them to become inherently unstable.  Engineering approaches to these channels have too often resolved the instability and flood carrying capacity issues by making the systems less ecologically robust, and far less interesting.  The current study reports on the results of using more holistic design criteria when restoring these degraded systems.  Bio-engineering approaches for system stability, inclusion of fisheries and wildlife habitat “structures”, alteration of the hydraulics of the system, alteration of hydrology to increase groundwater infiltration, inclusion of recreational and educational opportunities, and consideration for flood mitigation will be discussed and highlighted by case studies.  The development of pre-designed prototypes for use in restoring longer reaches of a system will also be discussed, as will the advantages and disadvantage of this approach.