Closing Plenary   11:00 am  (BACK)
Friday, September 25

Evaluation of Bed Form Diversity Following Dam Removal

Will Harman
Stream Mechanics
Raleigh, NC

Dam removals are increasing throughout the United States because of failing infrastructure and their negative effects on stream ecology. Dams prevent the upstream and downstream movement of some organisms, impede sediment transport processes, alter watershed hydrology, and have other negative ecological impacts. However, dams also provide human services, such as hydroelectric power, flood control, and recreation. One concern with dam removal projects is the increase in sediment supply to downstream reaches and the potential effect on bed form diversity. Negative effects could include filling of pools, siltation of aquatic habitats, and riffle aggradation.

This presentation provides innovative techniques for evaluating bed form diversity before and after dam removal. A case study will be used to show new methods for measuring depth variability, bed form mapping, grain size distributions, large woody debris, and underwater video. These methods are aggregated using the Stream Functions Pyramid Framework to show functional lift or loss in bed form diversity following dam removal.