Slide Number 1Slide Number 2river engineering is an old ideariver restoration is newermorphologic controlsgeneral restoration considerationssalmon habitat restoration (model #3)fluvial sub-environmentsstream & habitat scalesbasic river restoration stepsrestoration of LWDglobal forestsglobal forestsglobal forestsSlide Number 15de-snaggingLWD at pool-riffle scale LWD @ valley scaleLWD @ valley scalePosition in Channel NetworkWatershed ScaleLWD across scalesLWD sizeLWD restorationso:Slide Number 26Slide Number 27Slide Number 28Uvas CreekUvas Creek ‘restoration’where to look for context?but…what should they look like?and finally:River Restoration1. basic concepts2. restoration of LWD3. what are natural conditions?restoration:reestablishing structure and function of ecosystems (ecosystem as close as possible to pre‐disturbance conditions)rehabilitation:making land useful again after disturbance (not necessarily pre‐ disturbance condition)reclamation:intended to change biological capacity of a system (ecosystem is definitely changed)flood control, power, etc…river engineering is an old ideaoften driven by interest in restoring habitatbut, how do we do it?river restoration is newerconceptualmodel #1climatecatchment vegetationChannelmorphologyChannelmorphologygeologygeologygradientgradientvalley form valley formhydrologyhydrologyriparianveg.riparianveg.sediment& wood inputs sediment& wood inputsflowobstructionsflowobstructionsfastslowrate of changemorphologic controlsGeologyClimateRegional VegetationGeologyClimateRegional VegetationLand UsePollutionRiver EngineeringFloodplain DevelopmentRestoration/LWDFlow RegimeSediment RegimeWood RegimeFlow RegimeSediment RegimeWood RegimeHabitatStructure &DynamicsBiotic Condition(creature viability)general restoration considerationsconceptual model #2 (more specific to restoration)salmon habitat restoration (model #3)supply of water, sediment & wood salmon habitatfluvial sub‐environmentsriver environments we might consider:stream & habitat scalesat what scale do we want to restore:general steps for a particular site:1 . assessment/diagnosis: what needs restoring?2. design: how to accomplish this3. implementation: accomplishing it…can be pretty slow4. monitoring: is it working?context, context, contextspatial: what kind of stream is this?braided, meandering? cascade, step‐pool, pool riffle?temporal: what was the disturbance history?dam? logging? channel management? when?basic river restoration stepsrestoration of LWDLWD: large wood(y) debriswood acts as an impediment to flow:can cause flow convergence and scour pools that provide important habitator, can cause slower flow & aggradation (sediment buildup)global forestsforests have covered about one‐third of the Earth’s land surface during the Holocene (last ~11,000 yrs)but we have changed the extent of forest cover substantially... Oregon Amazon Cameroonglobal forestsfew of the worlds forests retain “frontier” conditionsremaining large intact natural forest ecosystems ‐ undisturbed and large enough to maintain all of their biodiversity (GFW)global forestsMuch 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 this legacy? To what degree are our perceptions of the role of wood in rivers due to this legacy?Snags on the Missouri Karl Bodmer, circa 1850 de‐snagginglog jams were significant obstacles to navigation and land development in the western USLWD at pool‐riffle scale more wood more poolsFor channels surveyed in AK and WA:plane‐bed morphology occurs only at low LWD loadingLWD can control the formation of pools and bars, and thereby channel reach morphology LWD @ valley scaleLog jams trap large amounts of sediment and can lead to aggradation along entire channel reachesLWD @ valley scaleBoth locally recruited trees and log jams delivered by debris flows can create alluvial valley bottoms in confined mountain streams.Position in Channel NetworkQueets River, WashingtonLog stepsBankfull benchMeander jamValley jamWatershed ScaleLWD across scalesLWD is important for channel morphologySpatial scale (meters)11010010,00011001000In‐ChannelPoolsCoverBankComplexityReachChannelSwitchingIslandsSloughsValley BottomWater,Sediment & Wood RoutingYearsLWD sizelarger logs typically ‘key members’ of log jamsbut, all sizes are importantlog length/channel widthlog diameter/channel depth121200keyrackedlooseLWD restorationrestoration of natural wood loading would take centuries:large key members take a long time to growso:reintroduction of large woody debris Cowlitz River Engineered Log Jams, 25 yr flood event 5 weeks after constructionChanges at the Cowlitz Site: 12/95 to 04/97Uvas Creekso, need to be careful designing restorationjanuary 1996july 1997Uvas creek did not want to meander was that it’s natural state?Uvas Creek ‘restoration’context, context, contextwhere to look for context?but…most ‘piedmont’ stream morphologies reflect incision through dam‐related alluvium they were not restored via mill pond filling!what should they look like?‘should’ is a loaded word…what is under the mill pond fill?‘beaver meadow’small, stable, vegetated channels & islandslots of woodand finally:10 commandments of river restoration (according to Dave):1. do no harm2. look beyond the channel to assess it in its context3. use native materials4. emulate natural analogs5. let channels do the work6. let the channel use its floodplain7. manage inputs to the system so that the river can fix itself8. use direct manipulation of the channel as a last resort9. allow for the river to make its own changes10. use qualified/appropriate personnel to design restoration
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