Ecological Outcomes from Flow Regimes in the

Murray-Darling Basin

Ian Overton

RiverSymposium

24/09/2009

Water for a Healthy Country

Project Team

• Sue Cuddy

• Matt Colloff

• Brent Henderson

• Tanya Doody

• Gary Caitchen

• Kim Pullen

• Heather McGinness

• Linda Merrin

• Carmel Cattalini

• Warren Jin

• Elliot Dovers

• Petra Kuhnert

• Paul Wettin

• Dave Penton

• Ian Szarka

• Tony Arthur

• Juan-Pablo Guerschman

• Julian Reid

• Jane Roberts

• Rod Oliver

• Mike Geddes

• Michael Stewardson

• Darren Baldwin

• George Ganf

• Richard Norris

• Qifeng Ye

• Robyn Watts

• Simon Treadwell

• Danny Simpson

NWC Ecological Outcomes Project

• Funded by the National Water Commission under the

„Raising National Standards Programme‟

• “While various environmental flow guidelines have been

developed through expert panels and from general

ecological principles, it is now timely to seek empirical

datasets to test and shed further light on these

principles”.

NWC Ecological Outcomes Project

The project was original designed to provide scientific

evidence for ecological outcomes for flow regimes

• What are the hypotheses from science and

management?

• What are the critical biophysical and flow links

(conceptual models)?

• What data is available to test?

• What hypotheses can we test?

• How transferable are these relationships?

Ecosystem Areas

• Geomorphology - Michael Stewardson

• Biogeochemistry - Darren Baldwin

• Plankton - Rod Oliver

• Invertebrates - Richard Norris

• Fish - Qifeng Ye

• Birds - Julian Reid

• Floodplain Vegetation - Jane Roberts

• Ecosystem Function - Matt Colloff

• Estuary - Mikes Geddes

Data Identified

• 269 Databases of 461 datasets

• Metadata inventory available

9%

19%

19%

13%

9%4%

10%

10%

5%

4%

41

15

36

76

75

39

51

19

38

15

Biogeochemistry

Plankton

Macroinvertebrates

Native fish

Waterbirds

Aquatic vegetation

Riparian/floodplain vegetation

Ecosystem function

Geomorphology

Estuary

The number and percentage of datasets identified in each of the 10 ecosystem areas.

The number and percentage of datasets identified by sector.

20

56

12

181

Academic

Federal

Other

State

7%

21%

4%

67%

Responses

Direct and

indirect

responses

Altered by external

factors

Ecosystem Response Conceptual Model

Management Plans

• 79 Management plans

5%

22%

29%

42%

3%4

17

23

33

0

2

Qld

NSW

VIC

SA

ACT

Estuary

The number of management plans in each region.

• How are plans developed?

• How are plans implemented?

• What do you do if you do not have enough water?

• What ecological outcomes do you manage with

flows?

Management Plans

Trends in the science supporting environmental water management hypotheses

Southern basin plans

• aspirational and science based hypotheses

• eg Eflow studies in Vic and MFAT for Murray.

• Science has been synthesized to flow/water needs recommendations

• Improved tools and hydrodynamic models for Icon sites

Northern basin plans

• aspirational hypotheses with less science support

• not synthesized with flow/water needs recommendations (Narran exception)

• “asset” level plans being developed Marshes, Gwydir

• DSS developed and hydrodynamic models for Marshes etc

Management Hypotheses

• 187 ecology:flow hypotheses

Management Hypotheses

• ExampleEcological objective Magnitu

deInter-flood Period

Frequency

Clustering

Duration

Depth Seasonality Reference/Rationale

Restore self-sustaining

populations of Pygmy Perch

and other native fish -

spawning

High

flows

6-9 in

10

years

2-4

mths

Win/spr/su

mm

Gunbower-

Koondrook-

Perricoota Icon Site

Environmental

Management Plan

2006–2007: MDBC

(2006)

Successful breeding of

thousands of colonial

waterbirds in at least three

years in ten

Flood 6-9 in

10

years

5-8

mths

Aug-Jan MDFWRC (2005)

Barmah,

Gunbower, Chowilla

Maintenance of red gum

community

Flood.

5000 to

70,000

ML/Day

one to

two

(1:1-2)

years

4-7

month

s and

no

more

than

24

month

s is

desira

ble.

Winter-

spring

(extending

into

summer for

regeneratio

n with a

wet winter-

spring

following)

NWC Eflow - Black

Swamp, WINDS

modelling (SKM

2004), MFAT

modelling and

flow regime

requirements in

Roberts and

Marston (2000) -

Chowilla, MDBC

(2003) - Barmah

Hydrology

• Collating hydrology across the basin

• Observed / recorded

• Modelled actual

• Modelled natural

• Future (median climate)

Impacts of Climate Change

Flood Model for the MDB

• Amalgamation of

existing mapping and

modelling

• Remote sensing

between inundation

mapping

Flood Mapping for the MDB

• MODIS (2000 – 2009)

• 250m pixels

• 8 day composites

• Whole of basin

• Landsat (1982 – 2009)

• 25m pixels

• River Murray

• Analysis

• Flooding

• Connectivity

• Drying

LANDSAT vs. MODIS

LANDSAT TM

27 Jan 2004

MODIS Terra (MOD09GA)

27 Jan 2004

NDVI for the MDB

• Using MODIS and Landsat

• Test relationship between flooding and response of

primary productivity

Basin Regionalisation

• Ecohydrological classification for whole of basin

• River reaches – hydrograph analysis

• Hydrology and hydrological alteration

• Floodplains – flood inundation

• Wetlands – connectivity

• Climate, groundwater, land change

• Refine analysis

• Extrapolate results

• Includes regulated reaches

Analysis strategy

0.0

0.2

0.4

0.6

0.8

1.0

Ecological response

time

tree h

ealth

1970 1980 1990 2000 2010

050000

100000

150000

Station SA4260903 Hydrograph

time

Dis

charg

e (

ML/d

ay)

1970 1980 1990 2000 2010

range of interest

Overview of analysis strategy

Ecological Response

Flow History

Hydrology

• flood magnitude

• flooding frequency

• inter-flood period (dry period)

• clustering of flooding events

• duration of flood or high flow

• depth of river, wetland or flood inundation

• seasonality of river flow, wetland or flood inundation

• rate of rise and fall of river, wetland and flood inundation

• velocity of water movement

• stabilisation of river flows or wetland inundation

• temperature

• turbidity

• oxygen concentration

• salinity

• acidity

Some Hypotheses Being Tested

3 - Floodplain primary production will increase with increasing frequency of floodplain inundation

9 – Riparian tree condition is the outcome of previous inundation history

11 – Fish abundance increases with increasing floodplain inundation

12 - Colonial nesting waterbird breeding increases in response to increased floodplain inundation in the southern MDB

14 – Ruppia presence in the Estuary increases with increasing estuarine area as a result of increased flows

15 – Fish abundance increases in the Estuary with increasing estuarine area as a result of increased flows

Riparian Vegetation

Gunbower,

Victoria

Riparian Vegetation

• Main factors are „proportion of wet days‟, „min and

median flood duration‟ and „max time between floods‟

• Red Gum confounded by proximity to water

• Grey box health increases with proportion of wet days

and maximum flood duration.

Red Gum

Grey Box

Flooding Characteristics

Ruppia Extent over Time

Biomass

Years

Ruppia and Fish Response

Final Outcomes

• Science and management hypotheses

• Conceptual model/s of critical biophysical and flow

links

• Metadata inventory

• Statistical relationships

• Flood model

• Eco-hydrological

classification

• Basin assessment of

what is known and how

transferrable

Water for a Healthy Country

Healthy Water Ecosystems

Environmental Water

Ian Overton – Stream Leader

Phone: +61 8 8303 8710

Email: ian.overton@csiro.au

Thank You