arthington iwc e flows principles handout

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IWCEnvironmental 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 healthLoss of freshwater biodiversityDeclining food fisheriesLoss of human cultural values

Impacts on river flow regimes

levee banks on floodplainstsurface and groundwater

abstraction

weirs

high valuefree-flowing rivers

Minimal flow regime change

impacts ofwater gridsand IBTs

dam release rules

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Environmental FlowsEnvironmental flows describe the quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-b i th t d d thbeing that depend upon these systems

Brisbane Declaration 2007International Environmental Flows

Conference, Brisbane, September 2007750 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 MethodologyDownstream 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

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Ecological Significance of Natural Flow Regime

1. Poff et al. 1997. Natural Flow Regime Paradigm

2. Bunn & Arthington 2002Basic principles and ecological consequences of altered flow

regimes for aquatic biodiversity

3. Nilsson & Svedmark 2002Basic principles and ecological consequences of changing water

regimes: riparian plant communities

4. Pinay et al. 2002Basic principles and ecological consequences of changing water

regimes on nitrogen cycling in fluvial systems

5. Naiman, Bunn et al. 2002Legitimising fluvial ecosystems as users of water: An overview

Ecological Significance of FlowNatural 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.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

0

10

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30Mekong

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0.8 Darling

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Columbia

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8Cooper Creek

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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 zero flow or 100 year flood etce.g. zero flow, or 100 year flood, etc

• Duratione.g. number of days of low flow, or number of days thefloodplain 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

Aquatic biodiversity and natural flow regimes

channel formhabitat complexitypatch disturbance

biotic diversity

Principle 1lateral connectivitylongitudinal connectivity

Principle 3

spatesaccess to

Flow-ecology principles Bunn & Arthington (2002) Env. Management

Life history patterns • spawning• recruitment

Principle 2

natural regime discourages invasions

Principle 4

Time

Dis

cha

rge

spates

seasonalitypredictability

reproductive triggers

variability

floodplains

dispersaltriggers

stable baseflowsdrought

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Macro-scale(channel form)

Meso-scale (hydraulic units)

Flow creates and maintains:

•hydraulic habitat units- riffles, pools, floodplain wetlands

•channel form - headwater tributaries, main channels, lowland floodplains

•patches of habitat- undercut banks, boulders - gravel & sand beds, - aquatic plants- woody debris – snags- leaf litter packs

Micro-scale(patches within hydraulic units)

Images: Mark Kennard, Griffith University

pool

riffle

run

flow

• few species• streamlined body form • many species

• intermediate # species• streamlined body

Fish habitat preferences in riffles,

runs and pools

streamlined body form • many species• diverse body shapes

Images: Mark Kennard & Brad Pusey, Griffith University

Water surface

0.6

0.4

0.2

Purple spotted gudgeon(benthic species)

Rainbowfish(open water schooling species)

Relative water

Position in Water Column

0 20 40 60Stream bed

1

0.8

0 10 20 30

depth

Frequency (% of individuals)


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Substrate composition

0

10

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30Availability

Frequency of use

0

10

20

30

Substrate composition

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20

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Microhabitat structure

Availability

Frequency of use

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20 Juveniles

Adults

0


0

5



Impacts of flow regime alterations that change habitat downstream of dams and g

weirs

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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 theDarling River 1990-1991

Caused by:

• Stable low flows• Loss of flushing flows• Elevated nutrients• Ample light • Suitable water temps• Less grazing pressure

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Brisbane River d/s Wivenhoe Dam:Unregulated vs Regulated Flow

80000100000120000140000160000180000

150

200

250

300

low

ML

mon

thly

flo

w

020000400006000080000

JAN

FE

B

MA

R

AP

R

MA

Y

JUN

JUL

AU

G

SE

P

OC

T

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DE

C

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Mean Monthly Unregulated Mean Monthly RegulatedCoefficient of Variation Unregulated Coefficient of Variation Regulated

F

CV

of

m

• 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• habitat much less diverse• lower diversity of invertebrates and fish• reduced flood conveyance

Red water milfoil

Effects of Natural Flow RegimeEffects of Natural Flow Regimeon Riparian Vegetationon Riparian Vegetation

Before Flow RegulationLateral & longitudinalseed dispersal by hydrochory

Zonation of vegetationby flood frequency &duration e.g. herbs, shrubs, trees

Spatially and temporally heterogeneousplant community composition and structure

Biologically activezone e.g. decomposition

Usually diverseflora in comparisonto surrounding terrestrial system

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HydroHydro--ecological relationships: riparian ecological relationships: riparian vegetationvegetation

Tall She-oak (Casuarina cunninghamiana) riparian Along the channel verge there is a

bl b d f h h

Mature grassy open eucalypt (E. tereticornis) & bloodwood (Corymbia

tessellaris) woodland

Typical Typical zonation of riparian vegetation for SEQof riparian vegetation for SEQ

forest with mesic subcanopyspecies on channel terraces

stable band of reophytes such as Watergum (Tristaniopsis exilliflora),

Callistemon viminalis.& the Mat rush (Lomandra sp.)

Effects of changing the Flow RegimeEffects of changing the Flow Regimeon Riparian Vegetationon Riparian Vegetation

After Flow Regulation After Flow Regulation by Damby Dam

Barriers to seed dispersalby hydrochory, particularlyaffecting short-floating seedsStreamward migration

of vegetation zones,i.e. replacement ofhydrophytic species byy p y p ymore mesic/ xeric species.e.g. encroachment of forest Decomposition rates

decline with floodelimination

Homogenisation ofplant community composition & structure

Severe effects of reduced flood frequency on floodplain wetlands and waterbirds

Wetland loss in Australia:

•• 90 % loss in M90 % loss in M--D BasinD Basin•• 75 % loss on Swan Coastal Plain, WA75 % loss on Swan Coastal Plain, WA•• 50 % loss NSW coastal rivers50 % loss NSW coastal rivers

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biotic diversity


Principle 3

spatesaccess to

Principle 2Life History Patterns


Principle 2


Principle 4

Time

Dis

cha

rge

spates



variability

floodplains

dispersaltriggers


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 fishesN. Armstrong

No flow recruitment Spawning in standing water bodies N. Armstrong

Flow / flood pulse recruitmentSpawn during rising water levels or floods in spring & summer,

recruitment enhanced by backwater & floodplain inundation

Merrick & Schmida

Spawning in standing water bodieswith no flow, e.g. river pools, waterholes on floodplains

Eel-tailed catfish

R. Kuiter

Catfish spawns into a ‘nest’ in well-oxygenated water, water level fluctuations can inhibit spawning

R. McDowall

G. Schmida

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Flows trigger spawning in Clanwilliam Yellowfish

Spawning stimulated by flow cues below dams

Larval growth requires warm water

Skelton 1993

requires warm water and diverse food items

Seasonal reproductive cycles of fish species in the Fitzroy River system, QLD

A. agA. perAr. g.G. apr.pH. lep.Hyp. c.M. mog.N. aterOx. lin.P. gr.Scl. l.Sc. h.T. tan.

J A S O N D J F M A M J

wet seasonSummer temps

low & stable flowsSpring temps

Inversion of normal seasonal flow pattern below large dams

Flow and temperaturepatterns no longer match

L f fl d fl

Median monthly flowsMurray River at Albury, NSW

Loss of flood flows

Fish spawning failure

Loss of wetland biodiversityand functions

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Flow effects on different processes during a plant life cycle

Ecological responses to various temporal and spatial scale of flow disturbance

Adult

Growth and maturity

Flowering, seed set and release

JuvenileSeed

Seedling

Dispersal

Germination Establishment

y

Predation, competition



biotic diversity


Principle 3

spatesaccess to

Principle 3Movement and migration


Principle 2


Principle 4

Time

Dis

cha

rge

spates



variability

floodplains

dispersaltriggers


Movement and Migration

Freshwater Fishes of North-Eastern AustraliaPusey, Kennard & Arthington 2004

Merrick & Schmida 1984

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Giant Mekong Catfish(2.35 m and 260 kg)

“Construction of mainstream dams

that obstruct spawning migrations

may seal its fate”

Dudgeon, 2001Overfishing has caused failure of the Overfishing has caused failure of the

fisheryfishery

Importance ofconnectivity

Bust• Drying waterhole• Fish mortality 93%

Flood March200013,471 km2

• Fish return towaterholes

• Floodplain inundation• Fish breeding• Movement of all life stages

to floodplain• Growth and juvenile

recruitment

Channel flows• Connectivity• Movement• Fish breeding

Connectivity

Connectivity

Boom

11/12 native species move from river to inundated floodplains to feed and grow

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Water flowing to sea is not “wasted”

Year

Ann

ual f

low

(G

L)

Tota

l cat

ch (

tonn

es)

1945 1950 1955 1960 1965 1970 19750

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400

600

800

1000

1200

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Total fish catch

Total flow

Fish catch in Moreton Bay vs Logan River flow

Loneragan & Bunn 1999Aust. J. Ecol. 24: 431-440

1 000 000100 00010 000

0

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kings

total

Cat

ch

(to

nn

es)

Summer flow (ML)

Prawn catch in Logan estuary vs total summer flow

Mechanisms:• catchability• habitat & food resources • life history



biotic diversity


Principle 3

spatesaccess to

Principle 4Alien and translocated species


Principle 2


Principle 4

Time

Dis

cha

rge

spates



variability

floodplains

dispersaltriggers


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Impoundments provide habitat for exotic fish and plants (e.g. water hyacinth)

Ye

Mozambique tilapiahas established self-

maintaining populations n Wivenhoe and

North Pine Dams

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

Annual proportional flow deviation

- exotic species dominate, especially carp

Water fern – Salvinia - covering a riverine impoundment

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Effects of weirs on riparian & aquatic

vegetation

Between Marian and DumbletonWeir Pools - Pioneer R (Site 5)

Reach with natural flows

more stable water levels few native aquatic plants exotic species proliferate

Weir Pools - Pioneer R (Site 5)

Weir pool

Weir pool

Environmental FlowsEnvironmental flows describe the quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-b i th t d d thbeing that depend upon these systems

Brisbane Declaration 2007International Environmental Flows

Conference, Brisbane, September 2007750 delegates from over 50 countries

arthington iwc e flows principles handout

Technology

low flow

natural flow regime3

natural flow regimes

natural flow regimes

natural flow regime

natural regime

river flow regimes surface

macroscale flow