Normative Flow Studies

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Normative Flow Studies
King County Department of Natural
Resources Water and Land Resources Division

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Establishing links between flow regimes and
aquatic ecosystem health -

• Using a normative flow approach to guide river
  restoration in the PNW

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Flow Regimes and Restoration

• Historical conditions
• Ecological processes
• Prioritization
• Design

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Geology Climate Regional Vegetation Runoff
regime Sediment supply LWD supply
Land Use Pollution Roads CIPs Floodplain
Development Restoration/LWD
Biotic Condition (Salmon Viability)
Flow Regime
Habitat Structure Dynamics
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GEOLOGY, CLIMATE
Ecological Condition Reference Condition
Flow variables
Unaltered flow regime
Geomorphological, Biotic, Biogeochemical Variables
Key Flow Variables
Key Ecological Indicators
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Why has this not been done in PNW?

• Most information from
• Semi-arid/arid regions
• Hydroelectric/irrigation diversions
• Single-species bias
• Focus on minimum flows
• Noise associated with effects of urbanization
• Several efforts underway (TNC, King Co.,
  Ecology.)

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Approach
How have flows been altered? How has this
impacted PNW rivers?
Types of hydrologic alteration
Ecological effects of flow alteration
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Predicted Ecological Effects

• Literature review
• Focus on 1998-present
• Most common flow alterations
• Most common ecological responses
• Empirical relationships
• What is relevant to PNW?

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Literature Review Suites of Common Ecological
Effects
Habitat complexity
Connectivity
Community attributes
Life-history strategies
Q
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Changes in Flows ? Connectivity
Vertical
Longitudinal
Exchange of matter and energy
Lateral

• Flood pulse
• Nutrient cycling
• Productivity/food web support

Access to habitats
Population Viability

• Refugia
• All life-stages

• Dispersal
• Migration
• Recruitment

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Changes in Flow ? Habitat Complexity

• Channel form
• Patch complexity
• Disturbance regime

• Species Diversity

• Life-history Diversity

• Genetic Diversity
• Population Structure

• Population Persistence
• Productivity

Complex, Diverse
Simple, Uniform
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Changes in Flow ?Life-history
Seasonality Predictability Variability
Life-history strategies Recruitment/spawning Life
-spans, age at first reproduction
Timing first floods
Stable baseflows, drought
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Changes in Flow ?Communities
Community attributes Diversity Range
expansions/contractions Invasibility
Seasonality Predictability Variability
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Evaluate Flow ChangesIndicators and Metrics

• Connectivity
• Habitat Complexity
• Life-history Traits
• Community Attributes

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Habitat Complexity

• Spatial

• Number of
• Geomorphic surfaces
• Channel islands
• Un-vegetated patches
• Length channel segments

• Temporal

• Patch turnover rates
• Structural diversity
• Size classes trees
• Rates channel migration

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Life-History Traits

• Relative abundances/Presence-absence of
  life-history traits
• Timing of spawning runs
• Number of runs
• Length of reproductive season
• Short-lived vs. long-lived species
• Age at first reproduction
• Generations/year
• Tolerant/Intolerant

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Approach
Can we use flow regimes to design better river
restoration?
Predict effects of flow alteration on river health
Evaluate restoration actions under range of flow
regimes
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Flow Regimes and Restoration

• Historical flow regimes/existing constraints
• Current flow regimes/limitations
• Prioritization
• Design

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Prioritization
A-seasonal high or low flows
Flashiness
Timing of peak flows
Frequency overbank flows
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Restoration Design

• Feasibility
• Potential for success
• Goals and targets

Historical
Feasible
Priority 1 Restoration
Priority 2
Stewardship, Enhancement
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Flow Regime
Geomorphic Response
Frequency peak flows Magnitude peak flows

• Velocity
• Bedload transport capacity
• Depth of bedload scour (in relation
• to egg pocket depths)
• Grain size

Biotic Response Individual, Population
Biotic Response Community Composition

• Egg/alevin survival
• Population size (fall spawners)

• Salmon to cutthroat
• Invertebrate diversity
• Species diversity
• Life-history diversity