Naturalized Instream Diversion Design in an Avulsing Planform
Michael Scurlock, PhD, PE
AECOM
Glenwood Springs, CO
Authors: S. Michael Scurlock, PhD, PE, AECOM & Martha S. Cooper, The Nature Conservancy
The Gila River Headwaters is a unique and ecologically vibrant riparian corridor located in Southwestern New Mexico at the foot of the Mogollon and San Francisco Mountains. The Cliff-Gila Valley has long-standing agricultural water use through historical acequias; yet it remains one of the last free-flowing rivers in New Mexico.
The project setting comprises a highly dynamic and avulsing bedload river, sensitive riparian corridor and aquatic habitat concerns, desired natural aesthetics for structural modifications, minimized environmental impact potential from construction and maintenance activities, and an engaged local stakeholder group. Multiple in-stream diversion approaches have been recently proposed for the Gila River, ranging from rock and woody-debris natural-channel design structures to concrete and steel mechanically actuated channel-spanning diversion dams.
This presentation reviews the unique and unstable site constraints of the Gila River, investigates previously proposed diversion design approaches by others, and describes an improved site-specific diversion structure design developed using a quantified hydraulic and sediment transport modeling approach coupled with geomorphic response principles. The proposed design meets irrigation water needs, is hydraulically and morphologically stable, minimizes maintenance, achieves fish passage metrics, and works with the form and function of the river system.
About Michael Scurlock, PhD, PE
Michael specializes in open-channel hydraulics, sediment transport, bank stability, scour dynamics, and diversion and infrastructure hydraulics. He has 14 years of experience in research, analysis, and applied engineering design of open-channel hydraulics systems and instream structures. He has co-authored federal guidelines for bank and vertical channel stabilization and has published tools for rapid engineering assessments of channel stability structural solutions tailored to site specific constraints. His experience includes development of local-scale to system-scale alternatives for water-allocation, stream stability, floodplain activation, fish passage, and riparian habitat improvements with morphologically stable and functioning solutions.