San Miguel River Restoration: Geomorphology and Hydraulic Engineering as a Basis for Design

Geomorphologic and hydraulic engineering analyses were used to develop a restoration plan for an approximately 850 meter-long section of the San Miguel River in Telluride, Colorado. The objectives of the plan were to 1) develop a geomorphically stable design where there is a balance between sediment supply and transport capacity, 2) provide appropriate hydraulic conditions for optimizing aquatic habitat, and 3) develop the design in a manner that will maintain the flood carrying capacity of the channel. A sediment balance was achieved by controlling the sediment supply with a sediment trap at the upstream end of the project reach and improving the transport capacity by removing constrictions that impede the movement of water and sediment through the reach. Hydraulic conditions for aquatic habitat were optimized by creating a generally narrower and deeper channel with variability in flow depths and velocities (steps, pools, and riffles). Published research on natural channels was used to determine an appropriate channel shape, planform, and main-channel capacity. The flood carrying capacity of the channel was maintained by removing constrictions at existing bridge crossings, altering channel bed elevations, and providing flood conveyance in low floodplain areas adjacent to the main channel.