Developing & Implementing Ecosystem Flow Recommendations for the Savannah River (GA/SC) A Case Study...

Developing & ImplementingEcosystem Flow Recommendations

for the Savannah River (GA/SC)

A Case Study under the Corps-TNCSustainable Rivers Project

SkagitGreen

Roanoke

Bill Williams

Savannah

White, Black,Little Red

Sustainable Rivers ProjectCurrent Sites

Ashuelot

West

Lower Savannah River and Estuary

May 2002

April 2003

Oct 2002 -Feb 2003

March 2004(initial)

Ongoing

Developing & Implementing Ecosystem Flow RecommendationsSavannah River (GA/SC)

Orientation MeetingMay 2002

• Purpose: Launch a collaboration to collect and apply our best knowledge on flow-ecological process relationships to water management

• Invitees: Agencies, NGO’s, University Researchers, SREL

• Outcome: Designed a process and identified key contributors for defining a set of essential flow characteristics needed to sustain the ecological integrity of the Savannah River ecosystem

Preparation of Literature Review

(Oct - Nov, 2002)

• Conduct a literature review of sources that appear useful in informing ecosystem flow recommendations (Savannah and similar systems)

• Focus on the whole ecosystem, including the shoals, river-floodplain, and estuary

• Review for completeness by leading scientists in each of the three component areas

Preparation of Summary Report(Nov 2002 - Feb 2003)

• key findings about linkage between specific ecological flow components and biotic tolerances or dependencies

• pictorial models illustrating connection between natural hydrographs and life cycles of representative species

• box-and-arrow diagrams expressing relationships between ecological flow components and biotic responses or dynamics.

• Reviewed by leading scientists in the three component areas

Ecosystem Flow Workshop(April 2003)

Ecosystem Flow Workshop(April 2003)

• Workhop: 2½ days, >40 scientists (agencies, academics and NGO’s)

• Three break-out groups defined ecological flow recommendations for:(i) Augusta shoals;

(ii) river-floodplain section from Augusta shoals to estuary; and,

(iii) estuary

Low Flows, High Flow Pulses, Floods

• Full group integrated flow recommendations across the 3 river reaches

• Report generated; reviewed by all workshop participants

The goal is not to create optimal conditions for all species all of the time;

rather, we want to create adequate conditions for all native species enough

of the time.

These wouldflood Augusta

Savannah Flow Recommendations

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Ecosystem Flow RecommendationsSavannah River, below Thurmond Dam (River-Floodplain)

Low Flows

High FlowPulses

Floods

3,000 cfs; 3 successive years every 10-20 years• Floodplain tree recruitment

<5,000 cfs• Adequate floodplain drainage

• Create shallow water habitat for small-bodied fish

>8,000 cfs• Larval drift for pelagic spawners

50,000-70,000 cfs; 2 weeks, avg every 2 yrs• Maintain channel habitats

• Create floodplain topographic relief• Provide fish access to the floodplain

• control invasive species• Maintain wetlands and fill oxbows and sloughs

• Enhance nutrient cycling & improve water clarity• Disperse tree seeds

<13,000 cfs; 3 successive years, every 10-20 years• Floodplain tree recruitment

8,000-12,000 cfs;• Exchange water with oxbows

20,000-40,000 cfs; 2-3 days, 1/month• Provide predator-free habitat for birds

• Disperse tree seeds• Transport fish larvae

• Flush woody debris from floodplain to channel• Floodplain access for fish• Fish passage past NSBLD

>30,000 cfs; 5 pulses, >2 days with 2 eventsof 2 week duration (March and early April)

Key

Dry Year

Avg Year

Wet Year

Really?...Monitoring, Research, &Adaptive Management

High Pulse Release(March 2004 )

May 2002

April 2003

Oct 2002 -Feb 2003

March 2004(initial)

Ongoing

Steps for Developing Ecosystem Flow RecommendationsSavannah River (GA/SC)

Savannah RiverCase Study Summary

• Collaborated to define ecosystem flows:– done for the whole system (shoals,

river-floodplain, estuary)– applied best available science– completed in one year, for $90K

• Developing a strategic monitoring plan to assess dam re-operation and inform future management

• Modeling to assess multiple future scenarios

Developing Environmental FlowsA Multi-Level Approach

High Flow Pulses

0

5000

10000

15000

20000

25000

30000

35000

1885 1890 1898 1903 1925 1930 1935 1940 1945

Year

Riv

er F

low

(cf

s)

It’s recognized that...• River flow is a “master variable” for maintaining

the integrity of freshwater ecosystems

• Healthy freshwater ecosystems:– require that some semblance of the full range of

natural flow variability be maintained

– degrade the more we alter natural flow patterns

Goal: (of the instream flow studies) is “to conservebiodiversity and maintain biological integrity.”

-- TX Instream Flow Studies: Technical Overview, Aug 8, 03

Developing Environmental Flows

Challenges Include:– identifying what components of flow are ecologically

most critical in a particular river system– quantifying those flow components to help guide water

management– incorporating new knowledge and understanding into

water management over time– achieving these tasks for all rivers within resource

constraints

The Common Denominator

• Low Flows – Determine the amount of habitat available, necessary energy expenditures.

• High Flow Pulses – Open up additional habitat area, bring additional food material from upstream areas, moderate temperatures and oxygen levels, clean spawning gravels, and provide cues for migration to spawning areas

• Floods – Create the physical template of the river ecosystem, including formation of oxbows (backwaters) and secondary channels, floodplains, and spawning bars, and keep introduced species populations in check


From “Rivers for Life: Managing Water for People and Nature” by Sandra Postel and Brian Richter (Island Press 2003)

• Low Flows, High Flow Pulses, Floods

magnitude, frequency, duration, timing, rate of change

Approach: Systematic process to develop and incrementally refine environmental flows


• Level I: Hydrologic Desk Top Method

• Level II: Experts Workshop

• Level III: Detailed Instream Flow Studies

• Level IV: Adaptive Refinement

Developing Environmental FlowsA Four Level Approach

• Very quick and inexpensive (least rigorous)• Consider as a placeholder (for Levels II or III)• Uses hydrologic data only• Uses low flows, high flow pulses, floods

Level I, Characteristics

Apply Indicators of Hydrologic Alteration (IHA) software, Range of Variability Analysis

Indicators of Hydrologic Alteration (IHA)

• Statistical program

• Tool for analyzing hydrologic characteristics and changes in those characteristics over time

• Presents flow and flow alteration in ecologically meaningful terms…

low flows, high flow pulses, and flood flows (magnitude, timing, frequency, duration, rate of change)

High Flow Pulses

0

5000

10000

15000

20000

25000

30000

35000

1885 1890 1898 1903 1925 1930 1935 1940 1945

Year

Riv

er F

low

(cf

s)

1/3 “Bins”

High Flow Pulse Frequency

0

5

10

15

20

25

30

35

1885 1890 1898 1903 1925 1930 1935 1940 1945

Year

Nu

mb

er o

f ev

ents

per

yea

r

High Flow Pulse Duration

0

2

4

6

8

10

12

14

1885 1890 1898 1903 1925 1930 1935 1940 1945

Year

Ave

rage

du

rati

on in

day

s

• Modest time and money required (moderate rigor)• Relies on hydrologic data, existing ecological

research, and best professional judgement of experts

• Can be supplemented with a literature review and summary report

• Uses low flows, high flow pulses, floods

Level II, Characteristics

Level II: Savannah

• Expensive and time consuming (most rigorous)• Relies on hydrologic data, existing ecological

research, additional research fieldwork, and modeling (and best professional judgement of experts)

• Uses low flows, high flow pulses, floods

Level III, Characteristics

• Operational mode rather than a separate “Level”• Improves input to decision making• Acknowledges uncertainty (even in Level III)• Requires monitoring, with periodic review and

refinement as needed (~5 years)

Level IV, Characteristics

• Relies on the best available science• Designed to incorporate new knowledge and

understanding• Recognizes resource constraints

– different situations require different resources

Developing Environmental FlowsSummary of a Four Level Approach

Developing & Implementing Ecosystem Flow Recommendations for the Savannah River (GA/SC) A Case Study...

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