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Hat Creek Restoration Project Hat Creek Restoration Project HatRAC Presentation October 29, 2013 Prepared by Geomorphic Assessment and Preliminary Plans for Woody Debris Placement and Recreation Access Improvements Prepared for California Trout

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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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Page 1: Hat Creek Restoration Project

Hat Creek Restoration Project

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Prepared by

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

Improvements

Prepared forCalifornia

Trout

Page 2: Hat Creek Restoration Project

Project area/objectives

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

PROJECT AREA• Highway 299 upstream to

Powerhouse riffle

OBJECTIVES• Provide geomorphic

background for restoration activities

• Develop designs for recreation improvements

• Develop designs for introduction of large woody debris

PRESENTATION OUTLINE• Geomorphic overview• Large wood restoration• Recreation/access

improvements

Page 3: Hat Creek Restoration Project

Restoration approach/study methods

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

PROCESS-BASED RESTORATION• Replicate the geomorphic and ecosystem processes

that create habitat• Identify and describe processes• Identify human disturbance

METHODS• Review existing information• Stream walk survey• Topographic surveys• Field surveys of existing wood, and

potential wood placement areas• Review of instream wood inventory

conducted by CalTrout

WHY THIS APPROACH?• Target species likely to

show a positive response• Restoration measures less

likely to have negative unintended consequences

• Restoration measures more likely to function over long-term

Page 4: Hat Creek Restoration Project

Geomorphic processes: water and sediment

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Channel form is a reflection of the balance between flow and sediment

Source: Rosgen 1996

Page 5: Hat Creek Restoration Project

Water

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Flow very consistent over time

• Floods are not large• Hydropower has

limited, short-term effects

• Agricultural diversion lowers spring flood peaks, spring-summer flow

Sources: Kondolf et al. 1994

Page 6: Hat Creek Restoration Project

Sediment: suspended sediment

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

SOURCES• Bank erosion, overland

flows• Episodic, short-term

inputs from large-scale events

• Human disturbances that increase erosion have likely increased suspended sediment supply, but supply relatively low

EFFECTS OF DISTURBANCE• Increased sedimentation

in low velocity areas• Limited effect on channel

form, but may impact ecology

Page 7: Hat Creek Restoration Project

Sediment: bedload supply

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Large 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 can’t be transported due to low slope and lack of large floods

Source: Kondolf et al. 1994

TYPICAL SOURCES• Streambank erosion• Erosion of tributaries• Mass wasting upstream

in bypass reaches• General conclusions:

none of these sources account for bedload

Page 8: Hat Creek Restoration Project

Sediment: bedload supply

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Volcanic events can dramatically increase bedload supply—1915 eruption

• Transport through the system influences the bedload supply to the project area

• Flatter areas store sediment, affecting the rate of sediment supply and the size of sediment delivered to the project area

• Result—over decades following a volcanic event, increase in bedload supply rates to the project area

• Long intervening periods with low rates of sediment supply

Source: Kondolf et al. 1994

Page 9: Hat Creek Restoration Project

Recent sediment wave: influence of human disturbance

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Little effect on overall magnitude of supply

• Hydropower modifications have disrupted sediment transport in the system

• Likely a link between Baum Lake and the Powerhouse 2 bypass reach (Cook 2000)

• Channelization upstream of Cassel in 1950’s likely increased sediment supply, either by increasing transport capacity, erosion of the channelized reach, or both

• Episodic increases in sediment likely a natural process

Page 10: Hat Creek Restoration Project

Channel sediment reponse

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Hat Creek has limited transport capability due to consistent flow and low slope

• During periods of high sediment supply, transport capacity is exceeded and channel aggrades

Source: Rosgen 1996

Page 11: Hat Creek Restoration Project

Recent sediment wave

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Increased sediment supply resulted in a sediment wave over decadal time scales

• At any point in the channel, the wave caused an aggradation-degradation event as it passed

• Total 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)

Page 12: Hat Creek Restoration Project

Channel form

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Cross section rectangular, high width-depth ratio

• Relatively uniform width and depth• Peaty streambanks in low marshy

areas• Erosion rates low during periods of

low sediment supply

HUMAN DISTURBANCE• Introduction of muskrats

significantly increased streambank erosion rates and channel widening--possibly exacerbated by grazing

• Old Carbon Bridge may have caused widening downstream

• Riparian shrubs may have been reduced by grazing

Page 13: Hat Creek Restoration Project

Channel form and periods of high sediment supply

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

CHANNEL FORM• Depth variable in space and

time• Width 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 widening

• Widened areas may retain portions of the wave in narrow, longitudinal bars

ECOLOGICAL RESPONSES• Burial of aquatic vegetation• Aquatic vegetation reestablishment

constrained due to high bed mobility• Reduction in habitat diversity and

complexity

Page 14: Hat Creek Restoration Project

Model of channel function

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Infrequent, large-scale waves of sediment occur naturally• Resulting ADE may last decades• High rates of streambank erosion during aggradation may

result in widening, or side channels and avulsion during severe events

• As sediment supply decreases, backwater areas fill in with aquatic and emergent vegetation, creating peat and low-lying streambanks

• Narrow longitudinal bars may persist in widened areas after wave passage, likely to be eventually colonized by aquatic and emergent vegetation and resulting in narrowing

Page 15: Hat Creek Restoration Project

Woody debris-processes of large wood recruitment

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

POSSIBLE MODES OF LARGE WOOD

RECRUITMENT TO STREAMS

• Tree fall• Bank erosion• Wind throw• Soil saturation• Snow load• Fire• Disease

• Floating• Mass wasting

Page 16: Hat Creek Restoration Project

Large wood: recruitment in the project area

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Trees found on streambanks in much of lower half of project area

• Swampy areas unlikely to grow large trees

Page 17: Hat Creek Restoration Project

Large wood: human disturbance and wood supply

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Timber harvest likely removed potentially recruitable trees

• Subsequent grazing and management favored conversion to meadows

• Areas that are currently meadow may have historically had scattered large trees

• Current load of large wood (@5 pieces in the project area, CalTrout surveys) are likely lower than would have occurred naturally

Page 18: Hat Creek Restoration Project

Large wood: restoration opportunities

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

GEOMORPHIC EFFECTS• Work with existing

process of narrowing in wide areas

ECOLOGIC EFFECTS• Increase instream

habitat diversity and complexity

• Provide stable substrates for aquatic plant colonization

• Loafing habitat for turtles

• Substrates for macroinvertebrates

Page 19: Hat Creek Restoration Project

Large wood: habitat diversity and complexity I

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 20: Hat Creek Restoration Project

Large wood: habitat diversity and complexity II

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 21: Hat Creek Restoration Project

Large wood: habitat diversity and complexity III

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 22: Hat Creek Restoration Project

Large wood: preliminary wood plan

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

• Large 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 Considerations

• Mimic natural tree throw

• Rootwads will assure stability

• Disturbance of cultural resources

• Construction access/disturbance

Page 23: Hat Creek Restoration Project

Large wood: preliminary wood plan

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

STREAMBANK STABILIZATION

• Use of wood or other revetments to stabilize streambanks is not recommended

• Consider biotechnical treatments such as high-density willow planting

• Control of muskrats should be considered

Page 24: Hat Creek Restoration Project

Recreation Improvements I

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 25: Hat Creek Restoration Project

Recreation Improvements II

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 26: Hat Creek Restoration Project

Recreation Improvements III

Hat Creek Restoration Project HatRAC Presentation October 29, 2013

Page 27: Hat Creek Restoration Project

Recreation Improvements IV

Hat Creek Restoration Project HatRAC Presentation October 29, 2013