Biological Objectives Biological Objectives Tied to Physical Tied to Physical

ProcessesProcesses

Dr. William TrushDr. William Trush

Scott McBainScott McBain

Arcata, CAArcata, CA

OutlineOutline

Geomorphic-Hydrology work with BiologistGeomorphic-Hydrology work with Biologist

Geomorphic-Biotic linkagesGeomorphic-Biotic linkages

Attributes of alluvial river integrityAttributes of alluvial river integrity

Analytical techniques which include: Analytical techniques which include: Hydrograph component analysis, bar morphology, Hydrograph component analysis, bar morphology, integrationintegration

Reconsideration of standard techniques on Reconsideration of standard techniques on assessing impacts of damsassessing impacts of dams

Historical PerspectiveHistorical Perspective

Need to have a good understanding Need to have a good understanding of how the system historically of how the system historically functioned, both physical functioned, both physical components and biotic componentscomponents and biotic components

– EvaporationEvaporation– PrecipitationPrecipitation– Different SpeciesDifferent Species– Variety of hydrologic regimenVariety of hydrologic regimen– Variable geologyVariable geology

Conceptual FrameworkConceptual Framework

Supply /ControlSupply /Control

ProcessProcess

FormForm

HabitatHabitat

BiotaBiota

Watershed InputsWatershed InputsWater, sedimentWater, sediment

Fluvial Geomorphic Fluvial Geomorphic ProcessesProcessesTransport, depositionTransport, deposition

Geomorphic AttributesGeomorphic AttributesChannel morphology (size, shape, Channel morphology (size, shape, slope)slope)

Habitat Structure, Habitat Structure, ComplexityComplexityIn stream aquatic habitat, In stream aquatic habitat, woodlandswoodlands

Biotic ResponseBiotic ResponseAbundance and distribution of Abundance and distribution of native/exotic speciesnative/exotic species

For all take note of: Human land use and flow regulation, natural For all take note of: Human land use and flow regulation, natural disturbancedisturbance

Bottom-Up vs. Top-DownBottom-Up vs. Top-Down

Bottom-Up- BiologistBottom-Up- Biologist– Start under water, without Start under water, without

understanding the history and understanding the history and geomorphic processes. They never geomorphic processes. They never challenge the base line of the river.challenge the base line of the river.

Top-Down- GeologistTop-Down- Geologist– Start above water need to consider a Start above water need to consider a

biological stand point.biological stand point.

Have to approach both ways- Have to approach both ways- integration is the keyintegration is the key

Processes You Need To Go Processes You Need To Go Through…Through…

Data Data

Spend time getting historical Spend time getting historical condition, land and speciescondition, land and species

Conceptual modelConceptual model

ObjectivesObjectives

Priority HypothesisPriority Hypothesis

GeomorphicGeomorphic– Dam has eliminated upstream sediment Dam has eliminated upstream sediment

supply, decreasing in-channel coarse supply, decreasing in-channel coarse sediment storagesediment storage

SalmonidSalmonid1)1) Spawning gravel supply has been Spawning gravel supply has been

decreaseddecreased

2)2) Spawning habitat is limiting salmonid Spawning habitat is limiting salmonid productionproduction

Attributes of Alluvial RiversAttributes of Alluvial Rivers

Historical Model of “Trinity River”Historical Model of “Trinity River”– Look at conceptual models to identify Look at conceptual models to identify

key process and formation that key process and formation that maintained the ecosystemmaintained the ecosystem

– The process of developing the attributes The process of developing the attributes is most important and different for every is most important and different for every riverriver

Attributes of Alluvial Rivers Attributes of Alluvial Rivers cont.cont.

1)1) Spatially complex channel morphology Spatially complex channel morphology (migrate, meander, side channels)(migrate, meander, side channels)

2)2) Flows and water quality are predictably Flows and water quality are predictably variable (Trends in river that are variable (Trends in river that are consistent per year during certain times)consistent per year during certain times)

3)3) Bed moves frequently (1-2 year)Bed moves frequently (1-2 year)

4)4) Bed scour and fill (5-10 year)Bed scour and fill (5-10 year)

5)5) Balance fine and coarse sedimentBalance fine and coarse sediment

6)6) Channel migrates/avulsionChannel migrates/avulsion

Attributes of Alluvial Rivers Attributes of Alluvial Rivers cont.cont.

1)1) Floodplains (oxbows, fine sediment Floodplains (oxbows, fine sediment dep.)dep.)

2)2) Channel Resettling floods (20-50 Channel Resettling floods (20-50 yrs. Large scale geomorphic yrs. Large scale geomorphic change)change)

3)3) Plant communitiesPlant communities

4)4) Fluctuating ground water table Fluctuating ground water table (wetlands and animals)(wetlands and animals)

Channel ComplexityChannel Complexity

Very ComplexVery Complex

Point bars (plants), scours, oxbows, Point bars (plants), scours, oxbows, sheer zones/pools (fish), side sheer zones/pools (fish), side channels, variable particle sizechannels, variable particle size

Create and Maintain Channel Create and Maintain Channel MorphologyMorphology

HydrographHydrograph– Print our every hydrograph for the periods Print our every hydrograph for the periods

of record, develop hypothesisof record, develop hypothesis– Conduct water year analysis to evaluate Conduct water year analysis to evaluate

inter-annual flow variability (wet year vs. inter-annual flow variability (wet year vs. dry year)dry year)

– Intra-annual flow variability with in water Intra-annual flow variability with in water year, evaluate changes relate geomorphic year, evaluate changes relate geomorphic processes and life history of key biotaprocesses and life history of key biota

– Link biota to hydrologyLink biota to hydrology

Different water years = Different ecological Different water years = Different ecological functionsfunctions

ConditionCondition HydrologicHydrologic GeomorphicGeomorphic EcologicalEcological

Extremely Extremely

WetWet

Large winter floods, Large winter floods, large snowmelt large snowmelt runoff peak- melting runoff peak- melting occurs through Juneoccurs through June

Channel avulsion, Channel avulsion, migration, bed migration, bed load transport, bed load transport, bed scour, lots of fine scour, lots of fine sediment, sediment, floodplain scour floodplain scour and dep.and dep.

Vegetation Vegetation removal, woody removal, woody debris, greater debris, greater migration up migration up stream, high stream, high juvenile salmon juvenile salmon growth rates, low growth rates, low salmon out salmon out migration mortalitymigration mortality

NormalNormal Moderate winter Moderate winter floods, moderate floods, moderate snowmelt/runoff, snowmelt/runoff, moderate base flowsmoderate base flows

Moderate: Channel Moderate: Channel migration, bed migration, bed load transport, load transport, floodplain, fine floodplain, fine sedimentsediment

Minor veg. removal, Minor veg. removal, mod salmon mod salmon migration access migration access up stream, low up stream, low salmon out salmon out migration mortalitymigration mortality

Critically Critically

DryDry

Small winter floods, Small winter floods, miner snowmelt, miner snowmelt, short duration of short duration of runoff, higher water runoff, higher water temptemp

No channel No channel migration, no migration, no gravel transportgravel transport

Veg. lower in Veg. lower in channel, no scour, channel, no scour, low migration up low migration up stream, mod. stream, mod. Water temp- stress Water temp- stress mortality to mortality to salmon, moderate salmon, moderate salmon out salmon out migration mortalitymigration mortality

Other Biological HotspotsOther Biological Hotspots

Sediment depositionSediment deposition Channel complexity (bars, side Channel complexity (bars, side

channels)channels) Riparian vegetationRiparian vegetation Spawning areasSpawning areas Amphibian egg laying locationsAmphibian egg laying locations Large wood accumulationLarge wood accumulation

SuggestionsSuggestions

Historical perspective to understand how Historical perspective to understand how the system naturally workedthe system naturally worked

Hypotheses on how project changes the Hypotheses on how project changes the components of the system (Geomorphic-components of the system (Geomorphic-Biotic)Biotic)

Use top/down and bottom/up approach Use top/down and bottom/up approach with lots of coordination between physical with lots of coordination between physical scientist and biologistscientist and biologist

No river is the same, nor does every dam No river is the same, nor does every dam have the same impactshave the same impacts

Case Study 1Case Study 1

Overview of hydrology, Overview of hydrology, geomorphology, and channel geomorphology, and channel morphology of the Clavey Rivermorphology of the Clavey River

Develop hypothesesDevelop hypotheses Illustrate some conceptual models Illustrate some conceptual models

and analytical tools useful for access and analytical tools useful for access dam-related impacts to steep dam-related impacts to steep bedrock riversbedrock rivers

Summary of ChangesSummary of Changes

Substantial loss of flow volumeSubstantial loss of flow volume Substantial reduction on flood Substantial reduction on flood

magnitude and frequencymagnitude and frequency Constant year found base flowsConstant year found base flows Loss of coarse sediment supplyLoss of coarse sediment supply Reduction or loss of fine sedimentReduction or loss of fine sediment Downstream tributaries and valley Downstream tributaries and valley

walls still contribute fine and coarse walls still contribute fine and coarse sediment to channelsediment to channel

Potential ImpactsPotential Impacts

Accumulation of fine sediment and Accumulation of fine sediment and gravels in channelgravels in channel

Riparian and upland vegetation Riparian and upland vegetation intrusionintrusion

Abandoned side channels and ponded Abandoned side channels and ponded areasareas

Reduction of residual pool volume by Reduction of residual pool volume by gravel-boulder fillinggravel-boulder filling

And…And…

Potential ImpactsPotential Impacts

Reduced magnitude, duration, and Reduced magnitude, duration, and frequency of bed mobility of alluvial frequency of bed mobility of alluvial featuresfeatures

Reduced coarse sediment storage Reduced coarse sediment storage immediately downstream of the dam immediately downstream of the dam