The City of Valdez Community Development Department is responsible for managing three highly-dynamic braided river systems that drain rugged alpine terrain surrounding the city, which is built up on the floodplains, deltas, and alluvial fans of these rivers. This management is complicated by high (and highly variable) sediment supply, rapid lateral channel migration, sediment budget imbalances, and hydrogeomorphic events including glacier outburst floods and debris flows.

NHC was contracted to support DOWL in work to diagnose root causes of management challenges, quantify sediment budgets, and develop appropriate long-term strategies to manage channel migration, sedimentation, and bank protection infrastructure.

NHC applied morphologic methods to define sediment budgets for each of the three rivers and identified conditions ranging from rapid incision on Glacier Stream (30 feet over 50 years) to rapid sedimentation that has perched the Lowe River 10 feet above a built-up portion of its floodplain. Using this data as the basis, NHC has provided recommendations for appropriate and sustainable gravel management and bank protection design and repair along the rivers.