River Restoration River Engineering Flood Control River Restoration Habitat Improvement climate sediment inputs catchment vegetation channel engineering Time variable drivers riparian vegetation hydrological regime Timeconstant variables valley form channel gradient geology Geology Climate Regional Vegetation Flow Regime Sediment Regime Wood Regime Land Use Pollution River Engineering Floodplain Development Restoration LWD Habitat Structure Dynamics Biotic Condition Salmon Viability Habitat Scales The supply and transport of water sediment and wood interact to structure salmon habitat Over what range of scales does LWD influence channels Geomorphic Province Watershed Channel Reach Valley Segment Bar Pool Bar Riffle Pool River Restoration Sediment Water Wood Confinement Valley slope Channel morphology Flow obstructions Bank material Riparian vegetation River Restoration Application of general principles to the context of a particular site 1 Assessment diagnosis 2 Design 3 Implementation 4 Monitoring 10 Commandments of River Restoration I II III IV V VI VII Do no harm Look beyond the channel to assess it in context Use native materials Emulate natural analogs Let the channel do the work Let the channel use its floodplain Manage inputs to the system so that the river can fix itself VIII Use direct manipulation of the channel only as a last resort IX Allow for changes authored by the river X Use appropriate personnel to scope and design restoration efforts River Restoration Context Context Context Spatial What kind of stream is it Temporal What is its disturbance history River Restoration What kind of stream is it Braided meandering straight Cascade Step Pool Plane Bed Pool Riffle River Restoration Sediment Water Wood Confinement Valley slope Channel morphology Flow obstructions Bank material Riparian vegetation River Restoration Sediment Water Wood Confinement Valley slope Channel morphology Flow obstructions Bank material Riparian vegetation Wood in rivers Wood acts as an impediment to flow that can cause flow to converge and scour out pools that provide important habitat Extent of global forests Forests have covered about one third of the Earth s land surface during the Holocene But the extent of forest cover has changed substantially Oregon Amazon Cameroon Few of the worlds forests retain frontier conditions Much of our understanding of river systems was developed in areas that either lacked large wood or that had been cleared of wood debris To what degree are our perceptions of the role of wood in rivers due to such historic legacies Snags on the Missouri Karl Bodmer circa 1850 Log jams were significant obstacles to navigation and land development in the western U S Army Corps of Engineers aggressively desnagged American Rivers Snags Year Thousands of snags were removed from Puget Sound rivers between 1880 and the mid 20th Century 10000 Rivers Harbors Skagit River All Rivers 8000 6000 4000 2000 0 1880 1900 1920 1940 1960 Channel Unit Scale For channels we ve surveyed in Alaska and Washington a plane bed morphology occurs only at low LWD loading 20 pool spacing channel widths pool Greater wood loading leads to more pools plane bed pool riffle SE Alaska NW Washington 15 10 5 0 0 0 0 5 1 0 LWD frequency pieces m 1 5 Reach Scale LWD can control the formation of pools and bars and thereby channel reach morphology Valley Segment Scale Log jams trap copious amounts of sediment and aggrade entire reaches of channel Valley Segment Scale A B Both locally recruited trees and log jams delivered by debris flows can create alluvial valley bottoms in confined mountain streams 100 m 100 m Log jams can influence even large rivers NISQ Jams Other SNOH STILL Pieces Kilometer Valley jam Position in Channel Network Queets River Washington Log steps Meander jam Bankfull bench Watershed Scale Effects of Wood in Rivers 1000 Valley Bottom 100 Years 10 1 In Channel Pools Cover Bank Complexity 1 Reach Channel Switching Islands Sloughs 100 Water Sediment Wood Routing 10 000 Spatial scale meters How big does a log have to be in order to influence a river 2 basal diameter of bole mean bankfull depth Log diameter channel depth LWD Size and Channel Size Govern LWD Stability Influence 1 8 1 6 Key 1 4 1 2 1 0 8 0 6 Racked 0 4 0 2 0 Loose 0 K ey Ra c k e d 0 2 0 4 0 6 0 8 1 1 2 1 4 lo g le n g th b a n k f u ll w id th Log length channel width Loos e 1 6 1 8 2 River Restoration Reintroduction of large woody debris Restoration of natural wood loading would take centuries because of the time needed to grow large key member logs that can shape aquatic habitat ELJs Engineered Log Jams Engineered log jams are in stream flow control structures based on the architecture of naturally occurring stable log jams Floodplain channel dug Log Jam Placement Log Placement Cowlitz River Engineered Log Jams 25 yr flood event 5 weeks after construction Changes at the Cowlitz Site 12 95 to 04 97 Floodplain setbacks Levee relocation to allow floodway along rivers becoming increasingly popular as a restoration measure Re meandering Undoing channelization Kissimmee River Florida Provo River Utah Lower Duwamish River Seattle Restored reach formerly in a straight culvert Berkeley CA Uvas Creek January 1996 Uvas Creek July 1997 Uvas Creek restoration project Urban channels Thornton Creek Seattle Few opportunities for restoration Ham Creek Seattle Cuyahoga River 1952 What does it take to design a restoration project Should landscape architects do it The Grand Canyon is of course altogether valueless It can be approached only from the south and after entering it there is nothing to do but leave Ours has been the first and will doubtless be the last to visit this profitless locality It seems intended by nature that the Colorado River along the greater portion of its lonely and majestic way shall be forever unvisited and undisturbed Lieutenant Joseph C Ives report to Congress on the Colorado River 1861
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