eco_curve_methodology

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Flow Alteration – Biological Response
Relationships:
Proof of Concept of a Proposed Methodology
RTI Internal Research and Development
Project
RTI International
Project Objective:
To develop and test a space-for-time/cross-sectional
analysis approach to determine flow alteration –
biological response relationships:
–to support determination of ecological flows
e.g., Step 2 of BEC project
–that are useful to water resource managers

Objectives
Unaltered
Hydrograph
Current
Hydrograph
WaterFALL
Flow
Alterations
Aquatic
Biology
Monitoring
Data Flow Alteration
– Biological
Response
Relationships
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Methods
Flow alteration
–Data:
WaterFALLTM hydrologic data at each biological monitoring station
unaltered (Potential Natural Vegetation - PNV) and current (2006
NLCD + instream flow alterations) hydrologic conditions – expressed
as % change
40-year climate period (1967-2006)
–Metrics:
Based on TNC Indicators of Hydrologic Alteration (IHA) and
Ecodeficit metrics
Focused on reductions/decreases in flow (management focus)
Originally 67 metrics, now 23 metrics due to high degree of
correlation between metrics
magnitude, timing, and duration components of flow

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Methods
Flow alteration metrics

Metric
Group
Time Step
(months) Description
Number of
Metrics
Flow Regime
Component
EcoDeficit
Annual
Winter (12-3)
Spring (4-6)
Summer (7-9)
Fall (10-11)
Deficit in flow duration
curves between unaltered
and altered conditions
5 Magnitude
Timing
Minimum
Flow
Durations
Annual
Winter (12-3)
Spring (4-6)
Summer (7-9)
Fall (10-11)
3-, 7-, 30-, and 90-day
average minimum flows
(90 days not present in fall)
19
Magnitude
Duration
Timing
Total 23
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Methods
EcoDeficit and Ecosurplus
–From Vogel et al. (2007) and Gao et al. (2009)
High Flows
Low Flows
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Methods
Biological response metrics
–NC DWQ Fish community
dataset:
Most recent record (1990-2011)
858 monitoring stations
–Fish species (156) grouped by
habitat guild:
Pool (44 species / 675 stations)
Pool-run
Riffle-run (44 species / 650 stations)
Riffle
Margin
Backwater
–Metric
Species diversity
Abundance (total count)
Shannon Weaver Index

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Methods
Biological response metrics

Metrics normalized by 90th percentile value for each basin (i.e., “maximal
biological condition” in each basin)

Basin n Abundance Species Shannon
Broad 43 169 5 1.31
Cape Fear 72 95 4 0.89
Catawba 66 342 6 1.43
French Broad 73 674 10 1.76
Hiwassee 19 767 9 1.58
Little Tennessee 60 552 9 1.52
Lumber 12 15 1 0.00
Neuse 47 194 4 1.05
New 31 1512 11 1.62
Roanoke 37 419 11 1.84
Savannah 2 115 3 0.42
Tar 34 131 5 1.29
Watauga 19 625 5 1.09
Yadkin 136 419 7 1.44
90th percentile of biologic metrics for
riffle-run guild by basin
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Methods
Statistical Analyses:
–Focused on 90th percentile of data (to represent upper limit of
response attributable to flow alteration)
–Normalized data by basin
–Analyzed at state level
–Linear vs. non-linear response function
best fit determined by residual deviance
Thresholds of biological response:
–Flow alteration associated with 10, 20 and 30% reduction in
“biological condition”

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Results
Riffle-run guild
7%
11%
Annual Ecodeficit (%)
16%
11%
15%
21%
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Decrease in Annual Average
Minimum 90-Day Flow (%)
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Results
Pool guild
7%
11%
Annual Ecodeficit (%)
16%
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Decrease in Annual Average
Minimum 90-Day Flow (%)
11%
26%
>100%
23%
34% 47%
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Results
Changes in flow associated
with a 10% decrease in the
maximum biologic condition
Generalized Linear Model
Exponential Decay Model
Flow Metrics Abundance Species Shannon
Annual Deficit 6 7 5
Winter Deficit 6 7 5
Spring Deficit 6 7 6
Summer Deficit 8 9 8
Fall Deficit 11 10 10
Annual 3 Day 10 11 11
Annual 7 Day 8 5
Annual 30 Day 13 13 11
Annual 90 Day 12 11 10
Winter 3 Day 9 9 8
Winter 7 Day 8 9 4
Winter 30 Day 9 10 8
Winter 90 Day 9 10 8
Spring 3 Day 9 11 8
Spring 7 Day 8 8 9
Spring 30 Day 11 12 13
Spring 90 Day 11 11 12
Summer 3 Day 10 13 12
Summer 7 Day 9 6
Summer 30 Day 14 14 12
Summer 90 Day 17 14 15
Fall 3 Day 12 12 8
Fall 7 Day 12 13 10
Fall 30 Day 12 12 10
Average 10 11 9
Deviation 2.7 2.1 2.9
NS
NS
Not significant (p <0.05) NS
Riffle-run guild
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Flow Metrics Abundance Species Shannon
Annual Deficit 25 11 13
Winter Deficit 31 11 13
Spring Deficit 22 11 13
Summer Deficit 21 15 14
Fall Deficit 28 21 25
Annual 3 Day 20 16 17
Annual 7 Day 17 11 15
Annual 30 Day 26 29
Annual 90 Day 23 24
Winter 3 Day 38 33 31
Winter 7 Day 28 31
Winter 30 Day 16 19
Winter 90 Day 16 18
Spring 3 Day 16 20
Spring 7 Day 28 14 14
Spring 30 Day 31 19 21
Spring 90 Day 31 21 24
Summer 3 Day 23 17 19
Summer 7 Day 14 19
Summer 30 Day 24 31
Summer 90 Day 36 22 28
Fall 3 Day 26 14 17
Fall 7 Day 32 24 27
Fall 30 Day 30 22 21
Average 27 18 21
Deviation 6.3 5.7 6.1
Results
Changes in flow associated
with a 10% decrease in the
maximum biologic condition.
Generalized Linear Model
Exponential Decay Model
NS
NS
NS
NS
NS
NS
NS
NS NS
Not significant (p <0.05)
Pool guild
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Potential applications:
Develop these relationships for each stream class
–i.e., BEC system
Adopt these relationships for all “monitorable” streams
(i.e., stream classification may not be necessary):
–Riffle-run guild:
Mountains and Piedmont
–Pool guild:
Mountains, Piedmont, and Coastal Plain
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Potential Applications
Monitoring sites with riffle-run guild present
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Potential Applications
Monitoring sites with pool guild present
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Potential Applications
Where can the flow-biology relationships be applied?
–To all streams that are “monitorable”
Maximum drainage area
Wadeable for stream length of 600 ft

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Questions?
Fall Creek