Understanding restoration of Oregon's Wood River through multi-modal hydrogeomorphic monitoring
Abstract
Channelized reaches of the lower Wood River in the Upper Klamath Basin of Oregon have undergone extensive restoration since the late 1990's, when the Bureau of Land Management began managing for the benefit of redband trout and other native-endemic species. Restoration included reconstruction of a floodplain and channel meanders, narrowing and deepening of channel, and excavation and reoccupation of fluvio-deltaic channels connecting the river to the Upper Klamath-Agency Lake system. The goals of this study were to extend the restoration monitoring record and evaluate post-restoration performance in light of this record. Monitoring included channel-bathymetry mapping, measurements of sediment transport (bedload), and measurement of discharge at points throughout the project reach under differing stage conditions. Results indicate two distinct domains of channel response to restoration: (1) an upstream domain marked by aggradation in the early and incision in the late post-restoration periods, and (2) a downstream domain marked by the inverse responses of degradation in the early and aggradation in the late post-restoration periods. These domains are separated by the confluence of an artificial channel maintained for boating access. Flow and sediment-transport continuity are interrupted at this confluence. At high stage (winter/spring) impoundment from the lake stalls flow, inducing sediment deposition. Stage falls as lake level recedes in the summer and stream power is restored, thereby releasing the sediment trapped at high stage. Aggradation in the downstream domain coupled with excavation of a birdfoot distributary in 2010 combined to initiate an avulsion from one distributary to another during the 2015 flow recession. With the exception of this recent avulsion, monitoring data suggest the channel system is approaching a dynamic equilibrium and behaving consistently with the rate law in geomorphology. This study provides the first known synthesis of long-term geomorphic monitoring of a freshwater fluvio-deltaic channel restoration in the Pacific Northwest.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMEP43A1869D
- Keywords:
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- 1813 Eco-hydrology;
- HYDROLOGY;
- 1820 Floodplain dynamics;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY