HR: 09:30h
AN: NB21G-05 INVITED     [Abstracts]
TI: Conflicts in Performance Criteria and a Prioritization Methodology for Stream Restoration at the Watershed Scale
AU: * Goodwin, P
EM: pgoodwin@uidaho.edu
AF: Center for Ecohydraulics Research University of Idaho, Idaho Water Center 322 East Front Street, Suite 340, Boise, Id 83702 United States
AB: River restoration has become a significant consulting, agency and academic endeavor during the past decade with the driving force for these management activities including mitigation, total maximum daily load concerns, the preservation of critical habitat or recovery of endangered species. Review of restoration activities undertaken by agencies and academia in the 1980s showed that frequently it was difficult to identify the specific project goals or quantifiable metrics. Further, many projects lacked the resources for pre- and post- monitoring to establish project performance and to develop a feed-back mechanism into future design or management strategies. Now, a greater emphasis is being placed on the articulation of clear restoration objectives and post-implementation monitoring to evaluate the performance of individual projects. This trend has coincided with new advances in technologies that are allowing not only the success of individual projects to be quantified, but also how different projects interact. The objectives of specific restoration activities undertaken for different purposes may conflict at the reach or watershed scale. Through examples in Idaho and California, the difficulties in quantifying trends of both physical processes and linkages to ecological response will be illustrated. We look at some of the potential conflicts and benefits in restoration objectives within an individual project and the cumulative effects of a series of projects that may enhance or diminish some individual benefits. An analysis framework is outlined and the temporal and spatial frequency of sampling to detect the consequences of restoration actions is described. For example, two common actions in a channelized reach might be to (1) create a more natural channel section (reducing the width-depth ratio and enhancing geomorphic diversity), and (2) allow a more natural plan-form to restore the floodplain connectivity and sustain the geomorphic diversity. One performance metric that could be used is water temperature. The objective could be cooler conditions in the low flow summer months and larger areas of viable habitat in the winter months when sections of the stream freeze. The first action will reduce thermal gain as the width to depth ratio is reduced. However, the second may reduce low flow velocities, increase the residence time of water and tend to increase the thermal gain in the reach. The relative importance of each process (together with other factors such as shade and hyporheic exchange) will govern the magnitude of the change. A prototype tool for prioritizing restoration actions at the watershed scale that integrates a predictive model of the physical processes (flow, sediment transport and water quality) with the expected ecological benefits to quantify differences in alternatives and to prioritize potential management actions will be described.
DE: 1803 Anthropogenic effects
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly