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Arthington iwc e flows principles handout
1. IWC
Environmental Flows and Management
Scenarios
December 2009
Prof. Angela Arthington
Australian Rivers Institute, Griffith University
Room 1.09C, Building N13
3735 7403
Rivers and floodplains are the world’s most
threatened ecosystems
Global declines in river health
Loss of freshwater biodiversity
Declining food fisheries
Loss of human cultural values
Impacts on river flow regimes
surface and groundwater
levee banks on floodplainst abstraction
weirs
impacts of
water grids
high value and IBTs
free-flowing rivers
Minimal flow regime change dam release rules
1
2. Environmental Flows
Environmental flows describe
the quantity, timing and quality
of water flows required to
sustain freshwater and
estuarine ecosystems and the
human livelihoods and well-
being that depend upon th
b i th t d d these
systems
Brisbane Declaration 2007
International Environmental Flows
Conference, Brisbane, September 2007
750 delegates from over 50 countries
Management Scenario 1
Determining e-flows for a new reservoir
on a river like the Li Jiang
• Rapid assessment, with limited resources and data
DRIFT Methodology
Downstream Response to Imposed Flow Transformation
• Comprehensive assessment, with time to collect field data
ELOHA Framework
Ecological Limits of Hydrologic Alteration
Management Scenario 2
Prioritising e-flows for multiple assets when there is limited
water available because of other demands
Which wetlands should be given water and how much, when,?
g
Water allocations to sustain commercial fisheries
• Rapid assessment, with limited resources and data
Flow Restoration Methodology
• Comprehensive assessment, with time to collect field data
ELOHA Framework
2
3. Ecological Significance of Natural Flow Regime
1. Poff et al. 1997. Natural Flow Regime Paradigm
2. Bunn & Arthington 2002
Basic principles and ecological consequences of altered flow
regimes for aquatic biodiversity
3. Nilsson & Svedmark 2002
Basic principles and ecological consequences of changing water
regimes: riparian plant communities
4. Pinay et al. 2002
Basic principles and ecological consequences of changing water
regimes on nitrogen cycling in fluvial systems
5. Naiman, Bunn et al. 2002
Legitimising fluvial ecosystems as users of water: An overview
Ecological Significance of Flow
Natural Flow Regime Paradigm
Poff et al. (1997)
• The ecological structure and function of flowing water systems depends
largely on their natural dynamic flow regime
• Stream flow is a “master variable” that influences physical and chemical
characteristics, e.g.
- water quality
- sediment regime and substrate characteristics
- channel morphology, habitat structure and diversity
- energy sources that fuel the aquatic food web
• Stream flow characteristics influence the distribution, abundance and
biotic interactions of river and floodplain species
• Alteration of the natural flow regime of a river can have physical,
chemical and ecological impacts
Rivers differ in their natural flow regimes
Mekong 0.8 Darling
30
0.6
20
0.4
10
0.2
0
0
6
8 Mississippi Murray
6 4
4
2
2
0
0
Columbia 8
Cooper Creek
20 6
4
10
2
0 0
3
4. Components of natural flow regimes
Natural Flow Regime Paradigm - Poff et al. (1997)
• Magnitude of flow – discharge Q
• Frequency of occurrence – relates to a particular magnitude,
e.g.
e g zero flow, or 100 year flood etc
flow flood,
• Duration
e.g. number of days of low flow, or number of days the
floodplain is inundated, or composite values from flow
duration curve
• Timing, seasonality and predictability
• Rate of change, or flashiness
Bunn, S.E. and Arthington, A.H. (2002)
Basic principles and ecological consequences of altered
flow regimes for aquatic biodiversity. Environmental
Management 30: 492-507
1. Flow is a major determinant of physical habitat in streams, which
in turn is a major determinant of biotic composition
2. Aquatic Species have evolved life history strategies primarily in
direct response to the natural flow regime
3. Maintenance of natural patterns of longitudinal and lateral
connectivity is essential to the viability of populations of many
riverine species
4. The invasion and success of exotic and introduced species in
rivers is facilitated by the alteration of flow regimes
Flow-ecology principles
Bunn & Arthington (2002) Env. Management
Aquatic biodiversity and natural flow regimes
Principle 3
lateral connectivity Principle 1
longitudinal connectivity channel form
habitat complexity biotic diversity
patch disturbance
access to spates
floodplains
variability Principle 2
dispersal Life history patterns
Discharge
triggers • spawning
reproductive triggers • recruitment
seasonality
predictability
stable baseflows
drought
Time
Principle 4
natural regime discourages invasions
4
5. Macro-scale Flow creates and maintains:
(channel form)
•channel form - headwater tributaries,
main channels, lowland floodplains
•hydraulic habitat units
- riffles, pools,
floodplain wetlands
Meso-scale
(hydraulic units)
Micro-scale
(patches within
hydraulic units)
•patches of habitat
- undercut banks, boulders
- gravel & sand beds,
- aquatic plants
- woody debris – snags
- leaf litter packs
Images: Mark Kennard, Griffith University
Fish habitat
flow preferences in riffles,
runs and pools
run
riffle
• intermediate # species
• streamlined body
• few species pool
• streamlined body form • many species
• diverse body shapes
Images: Mark Kennard & Brad Pusey, Griffith University
Position in
Rainbowfish Water Column
(open water schooling species)
Purple spotted gudgeon
(benthic species)
Water surface
0.2
0.4
Relative
water 0.6
depth
0.8
1
0 10 20 30
Stream bed
0 20 40 60
Frequency (% of individuals)
Images: Mark Kennard & Brad Pusey, Griffith University
5
6. Substrate composition Frequency of use
30
20
Availability
30
10
20
0
10
0
30
Substrate composition
20
10
0
Images: Mark Kennard &
Brad Pusey, Griffith
University
Microhabitat structure
Frequency of use
Availability 20 Juveniles
15
Adults
10 15
5
10
0
5
0
Microhabitat structure
Images: Mark Kennard &
Brad Pusey, Griffith University
Microhabitat structure
Impacts of flow regime alterations that
change habitat downstream of dams and
g
weirs
6
7. Impacts of water loss and habitat change
downstream of dams and weirs
Sudden loss of flow and water depth, fish
stranding
The Lower Murray – a River of Lakes
Weir pools favour lentic Gastropods. River gastropods decline.
Caused by loss of river habitat & food resources (biofilms)
Blue-green algal blooms in the
Darling River 1990-1991
Caused by:
• Stable low flows
• Loss of flushing flows
• Elevated nutrients
• Ample light
• Suitable water temps
• Less grazing pressure
7
8. Brisbane River d/s Wivenhoe Dam:
Unregulated vs Regulated Flow
180000 300
CV of monthly flow
160000 250
140000
Flow ML
120000 200
100000 150
80000
m
60000 100
40000 50
20000
0 0
MAR
OCT
AUG
NOV
APR
JUN
MAY
FEB
JAN
JUL
DEC
Mean Monthly Unregulated SEP
Mean Monthly Regulated
Coefficient of Variation Unregulated Coefficient of Variation Regulated
• Reduced mean monthly flows
• Reduced flood peaks & “stepped” flow releases
• Elevated & more stable low flows
• Loss of flow variability at most flow magnitudes
Elevated, more stable low flows create habitat for
dense, extensive aquatic plant beds
Impacts:
• altered water quality, e.g. DO
Red water
• habitat much less diverse
milfoil
• lower diversity of invertebrates and fish
• reduced flood conveyance
Effects of Natural Flow Regime
on Riparian Vegetation
Before Flow Regulation
Lateral &
longitudinal
Zonation of vegetation seed dispersal by
by flood frequency & hydrochory
duration
e.g. herbs, shrubs, trees
Biologically active
Usually diverse zone
flora in comparison e.g. decomposition
to surrounding
terrestrial system
Spatially and temporally heterogeneous
plant community composition and structure
8
9. Hydro-
Hydro-ecological relationships: riparian
vegetation
Typical zonation of riparian vegetation for SEQ
Mature grassy open
eucalypt (E. tereticornis)
Tall She-oak (Casuarina & bloodwood (Corymbia
Along the channel verge there is a cunninghamiana) riparian tessellaris) woodland
stable band of reophytes such as
bl b d f h h forest with mesic subcanopy
Watergum (Tristaniopsis exilliflora), species on channel terraces
Callistemon viminalis.
& the Mat rush (Lomandra sp.)
Effects of changing the Flow Regime
on Riparian Vegetation
After Flow Regulation
by Dam
Barriers to seed dispersal
by hydrochory, particularly
Streamward migration affecting short-floating seeds
of vegetation zones,
i.e. replacement of
hydrophytic species by
y p y p y
more mesic/ xeric species.
e.g. encroachment of forest Decomposition rates
decline with flood
elimination
Homogenisation of
plant community composition & structure
Severe effects of reduced flood frequency on
floodplain wetlands and waterbirds
Wetland loss in Australia:
• 90 % loss in M-D Basin
M-
• 75 % loss on Swan Coastal Plain, WA
• 50 % loss NSW coastal rivers
9
10. Principle 2
Life History Patterns
Aquatic biodiversity and natural flow regimes
Principle 3
lateral connectivity Principle 1
longitudinal connectivity channel form
habitat complexity biotic diversity
patch disturbance
access to spates
floodplains
variability Principle 2
dispersal Life history patterns
Discharge
triggers • spawning
reproductive triggers • recruitment
seasonality
predictability
stable baseflows
drought
Time
Principle 4
natural regime discourages invasions
Life History and Recruitment Strategies
Low flow recruitment
Spawn during stable low
flows in spring & summer,
window of opportunity to
access habitat/food for larval
N. Armstrong fishes
No flow recruitment
N. Armstrong
Spawning in standing water bodies
with no flow, e.g. river pools,
waterholes on floodplains
Merrick & Schmida Flow / flood pulse recruitment
Spawn during rising water levels or floods in spring & summer,
recruitment enhanced by backwater & floodplain inundation
Catfish spawns into a ‘nest’ in well-oxygenated water,
water level fluctuations can inhibit spawning
Eel-tailed catfish
R. Kuiter
R. McDowall
G. Schmida
10
11. Flows trigger spawning in Clanwilliam Yellowfish
Spawning stimulated
by flow cues below
dams
Larval growth
requires warm water
and diverse food
items
Skelton 1993
Seasonal reproductive cycles of fish species
in the Fitzroy River system, QLD
A. ag
A. per
Ar. g.
G. apr.
p
H. lep.
Hyp. c.
M. mog.
N. ater
Ox. lin.
P. gr.
Scl. l.
Sc. h.
T. tan.
J A S O N D J F M A M J
low & stable flows wet season
Spring temps Summer temps
Inversion of normal seasonal flow
pattern below large dams
Flow and temperature
patterns no longer match
Loss of fl d fl
L f flood flows
Fish spawning failure
Loss of wetland biodiversity
and functions
Median monthly flows
Murray River at Albury, NSW
11
12. Flow effects on different processes during a
plant life cycle
Ecological responses to various temporal and spatial scale of flow disturbance
Flowering, seed
Adult
set and release Growth and
maturity
y
Seed Juvenile
Dispersal
Germination Establishment
Seedling
Predation, competition
Principle 3
Movement and migration
Aquatic biodiversity and natural flow regimes
Principle 3
lateral connectivity Principle 1
longitudinal connectivity channel form
habitat complexity biotic diversity
patch disturbance
access to spates
floodplains
variability Principle 2
dispersal Life history patterns
Discharge
triggers • spawning
reproductive triggers • recruitment
seasonality
predictability
stable baseflows
drought
Time
Principle 4
natural regime discourages invasions
Movement and
Migration
Merrick & Schmida 1984
Freshwater Fishes of North-Eastern Australia
Pusey, Kennard & Arthington 2004
12
13. Giant Mekong Catfish
(2.35 m and 260 kg)
“Construction of
mainstream dams
that obstruct
spawning migrations
may seal its fate”
Dudgeon, 2001
Overfishing has caused failure of the
fishery
• Fish return to
Flood March
2000
waterholes Importance of
13,471 km2 connectivity
Bust
• Drying waterhole
• Fish mortality 93%
Connectivity
Connectivity
Boom
• Floodplain inundation Channel flows
• Fish breeding • Connectivity
• Movement of all life stages
• Movement
to floodplain
• Growth and juvenile • Fish breeding
recruitment
11/12 native species move from river to inundated
floodplains to feed and grow
13
14. Water flowing to sea
is not “wasted”
1600
1400
Total fish catch
1200
Total catch (tonnes)
Annual flow (GL)
1000
Fish catch in Moreton
800
Bay vs Logan River
600
400
flow
200
Total flow
0 Loneragan & Bunn 1999
1945 1950 1955 1960 1965 1970 1975
Aust. J. Ecol. 24: 431-440
Year
total
Prawn catch in Logan
100 estuary vs total summer
Catch (tonnes)
kings
flow
10
Mechanisms:
0 • catchability
10 000 100 000 1 000 000
• habitat & food resources
Summer flow (ML)
• life history
Principle 4
Alien and translocated species
Aquatic biodiversity and natural flow regimes
Principle 3
lateral connectivity Principle 1
longitudinal connectivity channel form
habitat complexity biotic diversity
patch disturbance
access to spates
floodplains
variability Principle 2
dispersal Life history patterns
Discharge
triggers • spawning
reproductive triggers • recruitment
seasonality
predictability
stable baseflows
drought
Time
Principle 4
natural regime discourages invasions
14
15. Impoundments provide habitat for exotic
fish and plants (e.g. water hyacinth)
Mozambique tilapia
has established self-
maintaining populations n
Wivenhoe and
North Pine Dams
Y
e
Fish species diversity has declined with
increasing degree of flow regulation in the
Murray-Darling Basin
- more stable flows,
- less frequent flooding
- modified habitat, food,
spawning conditions
- native fish have declined
- exotic species dominate,
especially carp
Annual proportional flow deviation
Water fern – Salvinia - covering a riverine
impoundment
15
16. Effects of weirs on
riparian & aquatic
vegetation
Reach with natural flows
Between Marian and Dumbleton
Weir Pools - Pioneer R (Site 5)
Weir pool
more stable water levels
few native aquatic plants Weir pool
exotic species proliferate
Environmental Flows
Environmental flows describe
the quantity, timing and quality
of water flows required to
sustain freshwater and
estuarine ecosystems and the
human livelihoods and well-
being that depend upon th
b i th t d d these
systems
Brisbane Declaration 2007
International Environmental Flows
Conference, Brisbane, September 2007
750 delegates from over 50 countries
16