Environment Institute Seminar Series 7 Justin Brookes

Environment Institute Science Seminar Series 2009 Adapting to a drier Australia: The challenges facing water resources Presented by: Assoc. Prof. Justin Brookes

Acknowledgements Kane Aldridge Dan Rogers George Ganf David Paton

Overview
The importance of lakes and rivers
Running down of the lower River Murray
Dealing with a crisis
Investing wisely for the long-term

The value is greater than the exploitable resource
Conduit for transport of plant growth enhancer to farm
Pulp stored on stump RIVER FOREST

LAKES – The canaries in the landscape
Sensitive indicators of catchment modification and climatic conditions
Integrate across landscape, hydrology and climate

What are our lakes/rivers and wetlands telling us
Coorong
Lower lakes
Main River Channel
Chowilla

The realities of the current situation

Irrigation agriculture
Tourism and fisheries
Ramsar-listed wetland
Living Murray Icon site
Spiritual home of the Ngarrindjeri
The Coorong, Lower Lakes and Murray Mouth

A region at a cross-road…
Reduced Murray inflows
Drying of the Lower Lakes
Decline in water birds and estuarine fish
Siltation of the Murray Mouth
Hypersalinisation of the Coorong
5,000 – 15,000 1990’s 5,000 – 19,000 2000’s 23,000 – 36,000 1980’s 250,000 1960’s # small waders Years D. Paton, U. Adelaide Red-capped plover

Invertebrate Distributions MM NL SL

Southern most end

Links to food: Black Swan

Salinity tolerance

Salinity responses

CLLAMM ecology Salinity NORTH LAGOON 0 30 60 90 120 150 180 Scenario 1: ‘Do Nothing’ Scenario 2: Minimum Flow Scenario 3: Low Flow Scenario 4: Medium Flood Scenario 5: Large Flood SOUTH LAGOON 0 30 60 90 120 150 180 Scenario 1: ‘Do Nothing’ 1 Scenario 2: Minimum Flow Scenario 3: Low Flow Scenario 4: Medium Flood Scenario 5: Large Flood

Pumping options

The state of the Lower lakes
Limited water
Receding shoreline
Acid sulfate soils
Salinity incursions
Invasive species
( Ficopotamus )
Loss of habitat

Lower Lakes

Ficopotamus

Acid sulfate soils

Tookayerta Creek Finniss River Currency Creek Point Sturt Pen 6 – Goolwa Channel Project Photo - March 2008 (minus 0.43 m AHD) (A) $11.5 m, 6 wks Laffin Point (F) $3.3 m, 8 wks (F) $2.14 m, 8 wks (C) $13 m, 12 wks (D) $15.5 m, 20 wks (G) $45m, 32 wks (E) $100m, 50 wks Stony Point Clayton Mud Islands Mundoo Is Hindmarsh Is Dunn Lagoon Goat Is Goose Is Rat Is

Pomanda Island Weir Plus 0.1 m AHD

Lake Albert Strategy
Acid mitigation
Keep it wet
400-900 ML/day
Lake Albert Keep it wet 400-900 ML per day Photos: Paul Harvey

A future scenario CLLAMM ecology

700km Bloom from Albury to Swan Hill Main River Channel

Swan Reach
No significant nutrient input for 500km, 6 months
260km upstream from Mouth,
-1m AHD
Major observations
Macrophyte stands establishing as water draws down and clears
Phytoplankton productivity low
Absence of large zooplankton
Dominance by small rotifers
Compromised food web
Fish underweight, terrestrial subsidies
Brachionus

Propping up ecosystems Chowilla Horseshoe pre- and post-watering. CHOWILLA FLOODPLAIN

Environmental watering
If we water wetlands without connectivity then we have local benefit only
No new carbon to system
N,P to fuel river productivity

Regulator

Chowilla 5,655 ha inundated 6000 ML/day 10,000 ML/day +regulator mn Simulate 60,000 ML/day 9559 ha

The cost of mismanagement and drought
Wellington weir $160 million
Clayton weir $26 million
Pump water to Lake Albert $14million+
Pump out Coorong $15 million
Dredging Murray Mouth $32million+
Remedial reveg $10 million
Chowilla regulator $30 million
Pipes to Narrung, Milang $120 million
Desalination Plant $1.4billion+
(Annual operating cost $108million)

Engineering works should be viewed as interim measures for conservation not as permanent solutions to replace flow

Setting a flow target and sustainable diversion limits
Baseline flow set by downstream target 1850GL entitlement + 500 GL
maintain Coorong once salt pumped out
floods overlying this
Upstream impacts
Lakes maintained above 0.5m
Mixed river for cyanobacterial control
Connectivity main channel and wetlands
Chowilla flooded using regulator 1 year in 3

An unrealistic ask?
2350 GL baseline against 14000 GL historical
85% of SA water need
(212GL potable)
7% of national GDP from SA
Historical Cotton 7% water – 0.1% GDP Rice 6% water – 0.02% GDP

Lakes as canaries in the landscapes
The Canary in the coalmine
A Short but meaningful life
Are we racking up an environmental debt that we can never repay?
Act to build sustainable environmental and irrigation systems
Facilitate a transition to a drier state
Prepare to make tough choices
Spending on weirs and pumping to patch a broken system is short-term
Address the environmental water problem while it is “still affordable”
Supporting any engineering solutions must be a commitment to return freshwater flow in the medium term

Environment Institute Science Seminar Series 2009 Shifting species distributions under climate change Presented by: Professor Miguel Araújo Director, BIOCHANGE Lab National Museum of Natural Sciences, Madrid, Spain

Environment Institute Seminar Series 7 Justin Brookes

by University of Adelaide on May 19, 2009

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