A Braided River System in a Glacial Environment, the Copper River, Alaska

John Wooster


The Copper River Basin is a glacially dominated system with some of the highest discharge and suspended sediment loads per basin area in Alaska. The Copper River is currently adjusting to rapid uplift from the 1964 earthquake and a retreating glacial flux. The Copper River is a prime example of a glacial, braided system and affords an excellent opportunity for further investigation on braiding in a glacial environment. Glacial systems characteristically have high sediment loads, discharge, and slopes, which usually produce a braided river. Sediment discharge from a glacier to a proglacial river system is a complex and locally variable balance between fluvial transport capacity, sediment supply, topographic pathways between the glacial and proglacial environment, and glacial state of flux. Although why a river forms a braided channel is not completely understood, a high bedload supply, a width to depth ratio greater than 50, erodible bank material, and high stream power are essential factors for a braided system.