Normative Flow Studies

1
Normative Flow Studies
King County Department of Natural Resources Wat
er and Land Resources Division

2
Establishing links between flow regimes and
aquatic ecosystem health -

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

3
Flow Regimes and Restoration

• Historical conditions
• Ecological processes
• Prioritization
• Design

4
Geology Climate Regional Vegetation Runoff regi
me
Sediment supply LWD supply
Land Use Pollution Roads CIPs Floodplain Deve
lopment
Restoration/LWD
Biotic Condition (Salmon Viability)
Flow Regime
Habitat Structure Dynamics
5
GEOLOGY, CLIMATE
Ecological Condition Reference Condition
Flow variables
Unaltered flow regime
Geomorphological, Biotic, Biogeochemical
Variables
Key Flow Variables
Key Ecological Indicators
6
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.)

7
Approach
How have flows been altered?
How has this impacted PNW rivers?
Types of hydrologic alteration
Ecological effects of flow alteration
8
(No Transcript)
9
Predicted Ecological Effects

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

10
Literature Review Suites of Common Ecological
Effects
Habitat complexity
Connectivity
Community attributes
Life-history strategies
Q
t
11
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

12
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
13
Changes in Flow ?Life-history
Seasonality Predictability Variability
Life-history strategies Recruitment/spawning Li
fe-spans, age at first reproduction
Timing first floods
Stable baseflows, drought
Q
t
14
Changes in Flow ?Communities
Community attributes Diversity Range expa
nsions/contractions
Invasibility
Seasonality Predictability Variability
Q
t
15
Evaluate Flow ChangesIndicators and Metrics

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

16
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

17
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

18
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
19
Flow Regimes and Restoration

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

20
Prioritization
A-seasonal high or low flows
Flashiness
Timing of peak flows
Frequency overbank flows
21
Restoration Design

• Feasibility
• Potential for success
• Goals and targets

Historical
Feasible
Priority 1 Restoration
Priority 2
Stewardship, Enhancement
22
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