Hat Creek Restoration Project

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Hat Creek Restoration Project. Prepared by. Geomorphic Assessment and Preliminary Plans for Woody Debris Placement and Recreation Access Improvements. Prepared for. California Trout. Project area/objectives. PROJECT AREA Highway 299 upstream to Powerhouse riffle. OBJECTIVES - PowerPoint PPT Presentation

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Hat Creek Restoration ProjectHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Prepared by

Geomorphic Assessment and Preliminary Plans for Woody Debris Placement and Recreation Access Improvements

Prepared forCalifornia Trout1Project area/objectivesHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013PROJECT AREAHighway 299 upstream to Powerhouse riffleOBJECTIVESProvide geomorphic background for restoration activitiesDevelop designs for recreation improvementsDevelop designs for introduction of large woody debris

PRESENTATION OUTLINEGeomorphic overviewLarge wood restorationRecreation/access improvements2Restoration approach/study methodsHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013PROCESS-BASED RESTORATIONReplicate the geomorphic and ecosystem processes that create habitatIdentify and describe processesIdentify human disturbance

METHODSReview existing informationStream walk surveyTopographic surveysField surveys of existing wood, and potential wood placement areasReview of instream wood inventory conducted by CalTroutWHY THIS APPROACH?Target species likely to show a positive responseRestoration measures less likely to have negative unintended consequencesRestoration measures more likely to function over long-term

3Geomorphic processes: water and sedimentHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Channel form is a reflection of the balance between flow and sediment

Source: Rosgen 1996

4WaterHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Flow very consistent over timeFloods are not largeHydropower has limited, short-term effectsAgricultural diversion lowers spring flood peaks, spring-summer flow

Sources: Kondolf et al. 1994

5Sediment: suspended sedimentHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013SOURCESBank erosion, overland flowsEpisodic, short-term inputs from large-scale eventsHuman disturbances that increase erosion have likely increased suspended sediment supply, but supply relatively low

EFFECTS OF DISTURBANCEIncreased sedimentation in low velocity areasLimited effect on channel form, but may impact ecology6Sediment: bedload supplyHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Large body of prior work due to concerns about sediment wave: Kondolf et al. 1994; Cook and Ellis 1998; Cook 2000)Bedload mostly sand; larger sediment generally cant be transported due to low slope and lack of large floodsSource: Kondolf et al. 1994

TYPICAL SOURCESStreambank erosionErosion of tributariesMass wasting upstream in bypass reachesGeneral conclusions: none of these sources account for bedload7Sediment: bedload supplyHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Volcanic events can dramatically increase bedload supply1915 eruptionTransport through the system influences the bedload supply to the project areaFlatter areas store sediment, affecting the rate of sediment supply and the size of sediment delivered to the project areaResultover decades following a volcanic event, increase in bedload supply rates to the project areaLong intervening periods with low rates of sediment supply

Source: Kondolf et al. 1994

8Recent sediment wave: influence of human disturbanceHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Little effect on overall magnitude of supplyHydropower modifications have disrupted sediment transport in the systemLikely a link between Baum Lake and the Powerhouse 2 bypass reach (Cook 2000)Channelization upstream of Cassel in 1950s likely increased sediment supply, either by increasing transport capacity, erosion of the channelized reach, or bothEpisodic increases in sediment likely a natural process

9Channel sediment reponseHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Hat Creek has limited transport capability due to consistent flow and low slopeDuring periods of high sediment supply, transport capacity is exceeded and channel aggrades

Source: Rosgen 1996

10Recent sediment waveHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Increased sediment supply resulted in a sediment wave over decadal time scalesAt any point in the channel, the wave caused an aggradation-degradation event as it passedTotal sediment volume in wave 60,000 cy; aggradation average about 1.5 ft (Kondolf et al. 1994)Wave has mostly passed through upper half of project area, crest likely around Wood Duck Island; passes out of project area 2010-2040 (Cook 2000)

11Channel formHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Cross section rectangular, high width-depth ratioRelatively uniform width and depthPeaty streambanks in low marshy areasErosion rates low during periods of low sediment supply

HUMAN DISTURBANCEIntroduction of muskrats significantly increased streambank erosion rates and channel widening--possibly exacerbated by grazingOld Carbon Bridge may have caused widening downstreamRiparian shrubs may have been reduced by grazing

12Channel form and periods of high sediment supplyHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013CHANNEL FORMDepth variable in space and timeWidth may increase due to higher streambank erosion rates (powerhouse riffle island, Cook 2000)Avulsion possible during severe events (backwaters in historic aerials, Cook 2000)During recent wave, bank instability caused by muskrats may have increased wideningWidened areas may retain portions of the wave in narrow, longitudinal barsECOLOGICAL RESPONSESBurial of aquatic vegetationAquatic vegetation reestablishment constrained due to high bed mobilityReduction in habitat diversity and complexity

13Model of channel functionHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Infrequent, large-scale waves of sediment occur naturallyResulting ADE may last decadesHigh rates of streambank erosion during aggradation may result in widening, or side channels and avulsion during severe eventsAs sediment supply decreases, backwater areas fill in with aquatic and emergent vegetation, creating peat and low-lying streambanksNarrow longitudinal bars may persist in widened areas after wave passage, likely to be eventually colonized by aquatic and emergent vegetation and resulting in narrowing

14Woody debris-processes of large wood recruitmentHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013POSSIBLE MODES OF LARGE WOOD RECRUITMENT TO STREAMSTree fallBank erosionWind throwSoil saturationSnow loadFireDiseaseFloatingMass wasting

15Large wood: recruitment in the project areaHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Trees found on streambanks in much of lower half of project areaSwampy areas unlikely to grow large trees

16Large wood: human disturbance and wood supplyHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Timber harvest likely removed potentially recruitable treesSubsequent grazing and management favored conversion to meadowsAreas that are currently meadow may have historically had scattered large treesCurrent load of large wood (@5 pieces in the project area, CalTrout surveys) are likely lower than would have occurred naturally

17Large wood: restoration opportunitiesHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013GEOMORPHIC EFFECTSWork with existing process of narrowing in wide areasECOLOGIC EFFECTSIncrease instream habitat diversity and complexityProvide stable substrates for aquatic plant colonizationLoafing habitat for turtlesSubstrates for macroinvertebrates

18Large wood: habitat diversity and complexity IHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

19Large wood: habitat diversity and complexity IIHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

20Large wood: habitat diversity and complexity IIIHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

21Large wood: preliminary wood planHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013Large woody debris loading can vary substantially between streams, even those with similar surrounding forest types, climate, and disturbance histories (Morris 2008)Final density and location determined by budget, aesthetics, fishing access, etc.Design/Construction ConsiderationsMimic natural tree throwRootwads will assure stabilityDisturbance of cultural resourcesConstruction access/disturbance

22Large wood: preliminary wood planHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013STREAMBANK STABILIZATIONUse of wood or other revetments to stabilize streambanks is not recommendedConsider biotechnical treatments such as high-density willow plantingControl of muskrats should be considered

23Recreation Improvements IHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

24Recreation Improvements IIHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

25Recreation Improvements IIIHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

26Recreation Improvements IVHat Creek Restoration ProjectHatRAC PresentationOctober 29, 2013

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