options for the environmental future of the river murray

55
The Environment Institute Water Research Centre Water Wednesday Managing the Murray Icon Sites: can engineering save the environment

Upload: university-of-adelaide

Post on 12-Nov-2014

926 views

Category:

Technology


0 download

DESCRIPTION

Judy Goode presents a seminar from the second Water Wednesday entitled "Options for the environmental future of the River Murray. Judy Goode is the SA River Murray Environmental Manager for the SA MDB NRM board.

TRANSCRIPT

Page 1: Options for the environmental future of the River Murray

The Environment Institute

Water Research Centre

Water WednesdayManaging the Murray Icon Sites:can engineering save the

environment

Page 2: Options for the environmental future of the River Murray

WATER WEDNESDAY

Options for the environmental future of

the River Murray

Judy Goode

SA River Murray Environmental Manager

SA MDB NRM Board

Page 3: Options for the environmental future of the River Murray

Presentation Outline

– Overview of the River Murray

– Environmental challenges

– Functions and processes

– The Living Murray – Chowilla as a case study

– The Future?

Page 4: Options for the environmental future of the River Murray

Distribution of Australia’s

surface runoff

Source: Water and the

Australian Economy

– April 1999

1.0%

1.7%

0.4%

20.3%

23.3%

1.9%

0%

6.1%

0.3%

21.1%

10.6%

13.3%

Page 5: Options for the environmental future of the River Murray

What sort of river is the Murray?

Naturally the river is:

– Extremely low gradient (1m:30km fromLake Victoria to Murray Mouth)

– Slow flowing

– Saline

– Turbid

– A river of extremes

and now in addition to these attributes:

– Highly regulated

– Greatly reduced flow

– Prolonged drought

Page 6: Options for the environmental future of the River Murray
Page 7: Options for the environmental future of the River Murray
Page 8: Options for the environmental future of the River Murray

How has the river changed?

• Before diversions and regulation the mean (average) annual runoffwas ~25 000 gigalitres, of which 50% reached the sea afterevapo-transpiration, seepage and retention in wetlands etc

• Between 1920 and 2000, the level of diversion increased from~2000 gigalitres/year to ~12 000 gigalitres/year

• Extractions tripled in the 50 years to 1994

• In 2000, 61% diversions in NSW, 30% Victoria, 5.5% Queenslandand 3.5% SA – almost equivalent to the mean natural dischargepre-development

• Changes to flood flows due to storages and regulation

• Contemporary thinking is that a river is likely to exhibit significantstress if flow regime is reduced below 2/3 of natural (TLM SRP)

• Medium floods reduced from 1:3 to 1:8 years

Page 9: Options for the environmental future of the River Murray
Page 10: Options for the environmental future of the River Murray
Page 11: Options for the environmental future of the River Murray

Lake Victoria

Menindee Lakes

Dartmouth Dam

Hume Dam

Barmah Choke

Page 12: Options for the environmental future of the River Murray
Page 13: Options for the environmental future of the River Murray
Page 14: Options for the environmental future of the River Murray
Page 15: Options for the environmental future of the River Murray
Page 16: Options for the environmental future of the River Murray
Page 17: Options for the environmental future of the River Murray
Page 18: Options for the environmental future of the River Murray
Page 19: Options for the environmental future of the River Murray

Factors Affecting the health of the system

• Significantly fewer floods - changes to flood frequency, timing and duration due to regulation and over-allocation

• Unseasonal delivery of water to support consumptive uses - high flowsnow predominantly delivered in summer/autumn cf natural delivery inwinter-spring

• Limited capacity to deliver water to SA

• Salinity build up on floodplain with limited flooding

• Flow times exacerbating management issues

• Risk of algal blooms due to low flows

• Deterioration of “river health” due to loss of connectivity between the river and the floodplain

• Conflicting management objectives – eg static water levels for irrigation and tourism vs weir pool manipulation for environmental outcomes

• Climate change and other risks

Page 20: Options for the environmental future of the River Murray

CSIRO Sustainable Yields Project• Provides govts with estimate of water availability in the MDB on an

individual catchment and aquifer basis, taking into account climate change and other risks

• Reduced run off and end of system flows under median and extreme dry climate change scenarios (assuming current development and allocation policies, and no recovery of e-water)

– Best estimate median 2030 climate average annual runoff reduced by 10 per cent

– Extreme estimates range from 41% reduction in the Murray (dry extreme) to 7% increase (wet extreme)

• Significant increases in the average time between beneficial floods

• These hydrologic changes would have very serious consequences for ecosystem health

• Wet extreme would lead to little change in flood frequency

Page 21: Options for the environmental future of the River Murray

What challenges does this present?Achieving a balance between the social, economic and

environmental outcomes of water management is a complex task facing water managers and governments

– Decisions taken in the past exploited the landscape for development and wealth

– Development over the last 100 years has resulted in biophysical, landscape scale change that we don‟t fully understand – river health has declined as the critical connection with floodplains has been reduced

– Biodiversity has significantly declined, including loss of native species and changes in vegetation – e.g. native fish populations estimated to be 10% of original numbers

– The long-term reliability and viability of all users depend on river health

– We are currently borrowing from the future

What are the shared and individual rights to the natural resources of the Basin and how are those rights to be managed?

Page 22: Options for the environmental future of the River Murray

What challenges does this present?The River Murray is a highly regulated river that supports communities and

regional/State economies, at the expense of the environment. How do we redress the imbalance?

• More water is clearly the answer, but we also:

– Need to „do more with less‟

– Important to identify key environmental assets using scientifically robust and consistent criteria, prioritisation frameworks and methodologies

– Take a one-River approach – Basin Plan?

– System approach – scalar

– Restoration projects - identify and agree key ecological processes

– Adaptive management approach – requires significant investment in monitoring, data interpretation

– Innovative solutions – engineering?

– Make explicit trade-offs and recognise the impacts

Page 23: Options for the environmental future of the River Murray

• Owing to the inherent complexity of rivers and an incomplete understanding of river systems, restoration projects that focus on reinstating ecological process are likely to be more successful than those which focus on fixed end points, particularly when:

There is a recognition that process and hence restoration projects are ongoing.

They are conducted at an appropriate scale. They are conducted with appropriate and sufficient scientific

monitoring. They are conducted within a multi-disciplinary and adaptive

management framework.

• Restoration of processes focuses on the causes of system degradation rather than the symptoms

FUNCTIONS AND PROCESSES

Page 24: Options for the environmental future of the River Murray

• Long-term strategies for managing flow regimes, land use and native biota are critical for restoring ecological integrity to rivers

• Temporal considerations are fundamental to river restoration. The natural timing, frequency, duration, magnitude and rates

of change of flow are each vital in restoring ecological processes

• Rare events (e.g. large floods which change river morphology) are also important and can have long lasting effects

• Temporal considerations need to recognize that natural variability is an inherent feature of river systems

• Hence restoration of an acceptable range of processes is more likely to succeed than restoration aimed at a fixed end point

Process based river restoration: Time scales

Page 25: Options for the environmental future of the River Murray

• Connectivity is an important ecological process

• Restoration projects should consider key processes and linkages beyond the channel reach, e.g. upstream/downstream connectivity, floodplain and hypoheic/groundwater connectivity

• Because physical, chemical, and biological processes are interconnected in complex ways across river systems, projects undertaken at this scale are more likely to be successful

• Because both technical and social constraints often preclude „full‟ restoration , rehabilitation should focus on the causes of system degradation through attainable reestablishment of processes and elements

Process based river restoration: Spatial scales

Page 26: Options for the environmental future of the River Murray

Purposeful move away from traditional focus on localised restoration to a landscape perspective (eg. habitat restoration and protection).

• Is there a response to local habitat reintroduction?

• How does the distribution of (restored) habitat influence the response of plants and animals?

• Where in the landscape should we invest for best outcomes?

• How do we prioritise environmental assets for water and works?

Theories and mechanisms of landscape ecology and hydrology

Page 27: Options for the environmental future of the River Murray

Example – managing individual habitats/issues

• Often isolated and uncoordinated

interventions at isolated sites

Source: Nick Bond

Removing willows

Re-snagging

Wetlands

Riparian revegetation

Environmental flows

Erosion control

Page 28: Options for the environmental future of the River Murray

Example – restoring populations & communities

Spawning habitat

Residential

habitat

Residential

habitat

Refuge

habitatResidential

habitat

Spawning habitat

•Coordinated restoration so

that interactions occur among

‘sites’.Source: Nick Bond

Page 29: Options for the environmental future of the River Murray

Critical Important Optional Desirable

Drought Average Flood

Scalable Site Management

Water Availability

Less More

Page 30: Options for the environmental future of the River Murray

Some local benefits but

many higher floodplain

areas still under-watered

Flow manipulation

Page 31: Options for the environmental future of the River Murray

Picture courtesy Fosters

Page 32: Options for the environmental future of the River Murray
Page 33: Options for the environmental future of the River Murray

Lake Littra pre-watering

13/9/2004

Page 34: Options for the environmental future of the River Murray

Lake Littra post-watering

23/3/2006

Page 35: Options for the environmental future of the River Murray

Twin Creeks pre-watering 2004

Page 36: Options for the environmental future of the River Murray

Twin Creeks post-watering 2004

Page 37: Options for the environmental future of the River Murray

General Description

Monoman Island Horseshoe

pre -watering August 2004

Page 38: Options for the environmental future of the River Murray

Monoman Island Horseshoe post

watering December 2004

Page 39: Options for the environmental future of the River Murray

Impacts of short-term actions

• Not sustainable long-term

• Does not address issues of connectivity

• Localised and small scale

• Expensive

• Only benefits some communities

• Not system approach

• Dose not necessarily target the highest priorities

Page 40: Options for the environmental future of the River Murray

Case Study - Chowilla Regulator

Page 41: Options for the environmental future of the River Murray

Current condition

Page 42: Options for the environmental future of the River Murray

Do Nothing 30 yr

Page 43: Options for the environmental future of the River Murray

Chowilla Ck Regulator

Page 44: Options for the environmental future of the River Murray
Page 45: Options for the environmental future of the River Murray
Page 46: Options for the environmental future of the River Murray
Page 47: Options for the environmental future of the River Murray

Natural inundation at 10,000 ML/day

Page 48: Options for the environmental future of the River Murray

Area inundated with regulator at 10,000 ML/day

Page 49: Options for the environmental future of the River Murray

Natural inundation at 70,000 ML/day

Page 50: Options for the environmental future of the River Murray

• Can be used at all flows to about 50,000 ML/day

• Levels can be raised up to 19.87 – 3.5 m increase

• Lock 6 to be raised 62 cm to top of piers

• Flow maintained through Chowilla Ck at all times

• Maintenance of velocity is important

• Likely to be operated 1 year in 3 on average

• Preference for >10,000 ML/day QSA for fulloperation

Regulator Operation

Page 51: Options for the environmental future of the River Murray

Recorded flow to SA (1977-2005)

0

20000

40000

60000

80000

100000

1200003/1

/77

3/1

/78

3/1

/79

3/1

/80

3/1

/81

3/1

/82

3/1

/83

3/1

/84

3/1

/85

3/1

/86

3/1

/87

3/1

/88

3/1

/89

3/1

/90

3/1

/91

3/1

/92

3/1

/93

3/1

/94

3/1

/95

3/1

/96

3/1

/97

3/1

/98

3/1

/99

3/1

/00

3/1

/01

3/1

/02

3/1

/03

3/1

/04

3/1

/05

Year

Flo

w

recorded f low to SA

Page 52: Options for the environmental future of the River Murray

0

20000

40000

60000

80000

100000

1200003/1

/77

3/1

/78

3/1

/79

3/1

/80

3/1

/81

3/1

/82

3/1

/83

3/1

/84

3/1

/85

3/1

/86

3/1

/87

3/1

/88

3/1

/89

3/1

/90

3/1

/91

3/1

/92

3/1

/93

3/1

/94

3/1

/95

3/1

/96

3/1

/97

3/1

/98

3/1

/99

3/1

/00

3/1

/01

3/1

/02

3/1

/03

3/1

/04

3/1

/05

Year

Flo

w

recorded flow to SA

simulated f low w ith regulator

Hypothetical Operational Regime

9 operations in 29 years

Page 53: Options for the environmental future of the River Murray

• Restoration of a floodplain regime that moreclosely resembles natural

• Enable 78% of RRG and 31% Black Boxwoodlands to be restored

• Inundation of large areas of other floodplaincommunities, including 91% of wetlands andother watercourses, 75% of river coobah and58% of floodplain grasslands

Benefits

Page 54: Options for the environmental future of the River Murray

• Real time salinity impacts

• Inhibits large bodied fish movement

• Blackwater events

• Weed infestation

• Algal blooms

• Operational objectives?

Risks

Page 55: Options for the environmental future of the River Murray

QUESTIONS?