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Preliminary flow records from small, mountainous channels on the Olympic Peninsula, Washington State
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  • Jeffrey Keck,
  • Teodora Minkova,
  • Warren Devine,
  • Erkan Istanbulluoglu
Jeffrey Keck
WA Dept. of Natural Resources, University of Washington

Corresponding Author:[email protected]

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Teodora Minkova
WA Dept. of Natural Resources
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Warren Devine
WA Dept. of Natural Resources
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Erkan Istanbulluoglu
University of Washington
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Channels and the water they convey control the spatial extent of aquatic ecosystems and the evolution of landscapes. Over geologic time scales (millions of years), flow rates have varied with changes in climate, glacial extent and tectonics; however, over shorter time scales, flow rates have remained stable enough to permit the establishment of unique ecosystems that depend on and interact with specific flow and sediment transport regimes. On the Olympic Peninsula, that relative stability was altered when humans converted vast areas of old-growth forest to tree plantations during the 20th century; however, because of the remote location and unstable nature of the channels affected by the tree farms, exactly how stream flow has changed is unknown. This study presents preliminary flow observations in the Olympic Experimental State Forest (OESF), a 110,000 ha block of public land on the west side of the Olympic Peninsula that is presently being managed for both timber and ecosystem values. Through repeat flow measurements and channel surveys and the installation of pressure transducers and staff gages, we are developing a long-term record of flow in small, (basin area 50 to 700 ha) step-pool to cascade channels that transport pulses of sediment and violently swing between low and high flows. Preliminary flow observations indicate that the geologic setting of the basin plays a large role in hydrograph characteristics and that picking out a vegetation signal in the flow record may be difficult. Nonetheless, the long-term goal of these observations is to quantify flow trends and help humans (The Washington State Department of Natural Resources) better understand how past and present tree harvests on the Olympic Peninsula may be altering natural hydrologic and geomorphic processes. Monitoring techniques we are using to measure flow in these small, dynamic streams, including the use of BaRatin (Le Coz et al., 2013) to develop rating curves, are presented. Future monitoring goals and plans to use the flow records for geomorphic and hydrologic modeling studies are also discussed.