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Water Availability in the Goulburn-Broken, Campaspe and Loddon-Avoca Murray-Darling Basin Sustainable Yields Project 12 May 2008 Project terms of reference Water Summit: PM and First Ministers, Nov 2006 CSIRO to report progressively

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SLIDE 1

Water Availability in the Goulburn-Broken, Campaspe and Loddon-Avoca

Murray-Darling Basin Sustainable Yields Project

12 May 2008

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SLIDE 2

Project terms of reference

  • Water Summit: PM and First Ministers, Nov 2006
  • CSIRO to report progressively through to mid 2008 on

sustainable yields of surface and groundwater systems within the MDB

  • Estimate current and likely future (~2030) water availability in

each catchment/aquifer and for the entire MDB considering:

  • climate change and other risks
  • surface-groundwater interactions
  • Compare the estimated current and future water availability to

that required to meet the current levels of extractive use

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SLIDE 3

Project Context

Water resource planning, management and investment

This Project Assessments

  • f current &

future water availability

Environmental impacts of alternate allocation regimes Socio-economic impacts of alternate allocation regimes Stakeholder and community consultation This project will not, in itself, determine sustainable yields or set a new cap on diversions

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SLIDE 4

Overview of methods

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SLIDE 5

Scenarios

A: Historic climate (1895-2006) & current development B: Recent climate (1997-2006) & current development C: Future climate & current development D: Future climate & future development

  • Future climate
  • 2030 climate based on 4AR IPCC results
  • 3 global warming levels (low, mid, high)
  • 15 global climate models
  • Future development
  • Commercial forestry plantations
  • Farm dams
  • Groundwater extractions

DJF JJA SON MAM

Autumn Summer Winter Spring

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SLIDE 6

Development

  • Commercial forestry plantations
  • projections for MDB regions
  • distribute projections in areas suitable for

plantations

  • Farm dams
  • current levels, trend analyses, policy

controls

  • Groundwater extractions
  • growth in extraction as per State advice
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SLIDE 7

Rainfall-runoff modelling

  • SIMHYD and Sacramento models on 5 x 5 km grids
  • Run for scenarios A and B (single runs)
  • Run for Scenario C (15 GCMs x 3 global warming levels)
  • From C select dry, mid, wet future: modify for Scenario D
  • Scenario D
  • Modify 3 runoff series from C for forest expansion
  • Adjust daily flows using “Forest Cover Flow Change” model
  • Modify 3 runoff series from C for farm dams
  • Adjust daily flows using a dam water balance model
  • Considers rainfall, evaporation, demands, inflows and spills
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SLIDE 8

River system modelling

  • Many different river models in use in Basin
  • Mostly daily time step, link-node models
  • These are being extended to 1895–2006
  • Groundwater exchanges being quantified
  • Models being linked and automated
  • Scenario modelled runoff series transformed as inflows
  • Some new models being developed
  • DSE Goulburn Simulation Model (GSM)
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SLIDE 9

Groundwater recharge

  • Diffuse recharge
  • WAVES: considers plant physiology and soil physics
  • Run at 20 point locations across MDB rain gradient
  • Consider range of land uses and soil types
  • Run scenarios A, B, Cdry, Cmid, Cwet
  • Analyse results to obtain recharge scaling factors
  • Apply across all groundwater management units on 5 km grid
  • Irrigation recharge
  • 1-D modelling for key irrigation areas, plus literature values
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SLIDE 10

Groundwater modelling

  • Prioritise groundwater management units (GMUs)
  • Extraction level, development level, potential for stream impact
  • 12 high & medium priority GMUs (~80% of resource)
  • Existing and new numerical groundwater models
  • Run models with scenario recharge series and current SW–GW

flux for 111 years (to equilibrium) and further 111 years

  • Provide equilibrium flux back to river models
  • Simple assessments for low priority GMUs
  • Connectivity mapping across all regions
  • Southern Riverine Plains Groundwater Model
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SLIDE 11

Water accounts

  • For nearly 600 river reaches across

the MDB independently assess:

  • Inflows
  • Outflows
  • Diversions
  • Floodplain losses
  • Direct evaporation
  • Exchanges with groundwater
  • Storages (rivers, lakes,

reservoirs)

  • Assess river model performance
c

423001 Warrego River @ Fords Bridge

Upstream gauge

423004 Warrego River @ Barringun #2

Reach length (km) 141 Area (km2) 5500 Outflow/inflow ratio 0.33 Net losing reach Land use ha % Dryland 192,715 35 Irrigable area
  • Open water*
  • River and wetlands
357,315 65 Open water*
  • * averages for 1990-2006
Gauging data Inflows Outflows Overall and gains and losses Fraction of total Gauged 0.67 0.22 0.44 Attributed 0.92 0.89 0.91 Fraction of variance Gauged 0.55 0.34 0.44 Attributed 0.95 0.99 0.97 Correlation with ungauged Gains Losses Linear adjustment normal ranked normal ranked Main gauge inflows
  • 0.26
  • 0.05
  • 0.92
  • 0.86
Tributary inflows
  • Main gauge outflows
  • 0.87
  • 0.46
  • 0.19
  • 0.43
Distributary outflows
  • Recorded Diversions
  • Estimated local runoff
  • 0.57
  • 0.30
  • 0.02
  • 0.26
Water balance Model (A) Accounts Difference Model efficiency Model (A) Accounts Jul 1990 – Jun 2006 Monthly Gains GL/y GL/y GL/y Normal <0 0.48 Main stem inflows 79 85
  • 6
Log-normalised
  • Tributary inflows
Ranked 0.68 0.28 Local inflows 75 33 42 Low flows only
  • Unattributed gains and noise
  • 10
  • High flows only
<0 <0 Losses GL/y GL/y GL/y Annual Main stem outflows 73 28 45 Normal <0 0.72 Distributary outflows Log-normalised
  • Net diversions
7 7 Ranked 0.72 0.97 River flux to groundwater
  • River and floodplain losses
86
  • 86
Definitions: Unspecified losses 75
  • low flows (flows<10% percentile ) : 0.0 GL/mo
Unattributed losses and noise
  • 14
  • high flows (flows>90% percentile) : 5.0 GL/mo
Change-uncertainty ratios P CH CM CL DH DM DL Annual streamflow 2.7 0.5 1.0 5.6
  • Monthly streamflow
2.8 0.6 1.0 5.4
  • 0.01
0.1 1 10 100 0.01 0.1 1 10 100 Annual Change-Uncertainty Ratio Monthly Change-Uncertainty Ratio 50 100 150 200 250 300 350 400 450 90/91 91/92 92/93 93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 Annual streamflow (GL/y) gauged A P CH CM CL DH DM DL 0.001 0.01 0.1 1 10 100 1000 20 40 60 80 100 Pecentage of months flow is exceeded Monthly streamflow (GL/mo) .
  • 400
  • 300
  • 200
  • 100
100 200 300 400 90/91 91/92 92/93 93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 Reach gains and losses (GL/y) unattributed gains ungauged gains gauged gains unattributed losses ungauged losses gauged losses This is a strongly losing reach. Flows are dominated by inflows from upstream. Most of the inflow is gauged. Estimated local runoff explains most of the ungauged gains but large adjustment of runoff model estimates was required. There are few diversions. Ungauged losses are large and attributed to wetland and floodplain losses. Baseline model performance is modest. Accounting explains
  • bserved flows moderately. The projected scenario changes are of
similar order to the uncertainty for CH and CM scenarios, and greater than uncertainty for P and CL scenarios. P C D + high
  • low
O medium 0.001 0.01 0.1 1 10 100 1000 Jun-90 Jun-91 Jun-92 Jun-93 Jun-94 Jun-95 Jun-96 Jun-97 Jun-98 Jun-99 Jun-00 Jun-01 Jun-02 Jun-03 Jun-04 Jun-05 Monthly streamflow (GL/mo) gauged accounted model
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SLIDE 12

Goulburn-Broken region

  • Area: ~2% of MDB
  • Pop: 144,000, 7% of MDB
  • Land use: dryland cereal

cropping and grazing, irrigated dairy and horticulture

  • Irrigation: 177,600 ha in

2000

  • Water use: ~14% of the

surface water diverted for irrigation in the MDB & ~5.4% of MDB GW use

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SLIDE 13

Campaspe region

  • Area: ~0.4% of MDB
  • Pop: 42,000, 2% of MDB
  • Land use:
  • dryland grazing
  • irrigated dairy
  • Irrigation: 32,500 ha in 2000
  • Water use:
  • ~0.2% of the surface water diverted

for irrigation in the MDB

  • ~1.7% of MDB GW use
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SLIDE 14

Loddon-Avoca region

  • Area: 2.3% of MDB
  • Pop: 142,000 (7% of MDB)
  • Land use
  • cereal cropping and grazing
  • irrigated dairy
  • Irrigation: 127,000 ha in 2000
  • Water use:
  • ~0.8% of the surface water diverted

for irrigation in the MDB

  • ~1.7% of MDB GW use
  • Kerang Lakes – Ramsar site
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SLIDE 15

River System Model

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SLIDE 16

Groundwater model

GMUs

  • Shepparton
  • Goorambat
  • Nagambie
  • Kialla
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SLIDE 17

Groundwater model

GMUs

  • Ellesmere
  • Campaspe Deep Lead

GMUs

  • Mid-Loddon
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SLIDE 18

Scenarios

A: Historic climate (1895-2006) & current development B: Recent climate (1997-2006) & current development C: Future climate & current development D: Future (~2030) climate & future development

  • Future climate
  • Mid, Dry, Wet
  • Future development
  • Farm dams
  • Commercial forestry plantations
  • Groundwater extractions
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SLIDE 19

Goulburn-Broken: key findings by scenario

  • Average surface water availability under the historical climate is 3233 GL/yr.

At the current level of development 1606 GL/yr (or 50 %) of this is diverted for use (including channel and pipe losses and transfers to other regions). This is an extremely high level of use. Groundwater use is 92 GL/yr or 10% of total water use.

  • If the recent (1997 to 2006) climate were to continue, average surface water

availability would be reduced by 41% and the volume of water diverted for use within the region would be reduced by 25%.

  • The best estimate (or median) climate change by 2030 would reduce average

surface water availability by 14% and would reduce the volume of water diverted for use within the region by 6%.

  • Future development of plantation forestry is expected to be negligible. An 8%

growth in farm dam capacity by 2030 is expected which would have a very minor (<1%) impact on river inflows. Groundwater extraction is expected to grow by 71% by 2030 to become around 16% of total water use.

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SLIDE 20

Campaspe: key findings by scenario

  • Average surface water availability under the historical climate is 275 GL/yr

and under current development 36% of this is diverted for use. This is a high level of use. Current groundwater use is about 30 GL/yr or 9% of total water use.

  • If the recent (1997 to 2006) climate were to continue, average surface

water availability would be reduced by 54% and the volume of water diverted for use within the region would be reduced by 26%.

  • The best estimate of climate change by 2030 would reduce average

surface water availability by 16% and would reduce the volume of water diverted for use within the region by 5%.

  • Future development of farm dams would reduce average annual runoff by

1.5%. Groundwater extraction is expected to increase by 10% by 2030.

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SLIDE 21

Loddon-Avoca: key findings by scenario

  • Average surface water availability under the historical climate is 285 GL/yr

and under current development 32% diverted for use. This is a high level of

  • use. Current groundwater use is about 29 GL/yr or 9% of total water use.
  • If the recent (1997 to 2006) climate were to continue, average surface water

availability would be reduced by 50% and the volume of water diverted for use within the region would be reduced by 27%.

  • The best estimate of climate change by 2030 would reduce average surface

water availability by 18% and would reduce the volume of water diverted for use within the region by 6%.

  • Future development of commercial plantation forestry and farm dams is

expected to have only minor impacts on runoff. Groundwater extraction in the region is expected to approximately double by 2030 to be 59 GL/yr.

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SLIDE 22

Overview by region

103% 10% 67% GW use increase 6% 5% 6% SW use reduction 18% 16% 14% Water availability reduction 32% 36% 50% Level of SW use 29 GL/yr 30 GL/yr 92 GL/yr GW use 92 GL/yr 99 GL/yr 1606 GL/yr SW use 285 GL/yr 275 GL/yr 3233 GL/yr Water availability Loddon-Avoca Campaspe Goulburn-Broken Current Best estimate 2030

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SLIDE 23

Current development & historic climate

92 GL/yr 99 GL/yr 1099 GL/yr

  • Int. diversions (use+loss)

32% 36% 50% Level of SW use 66 GL/yr 35 GL/yr 308 GL/yr Distribution losses 284 GL/yr 307 GL/yr 791 GL/yr SW use (total) 6 GL/yr 264 GL/yr 507 GL/yr SW transfers 285 GL/yr 275 GL/yr 3233 GL/yr Water availability 21 mm 69 mm 149 mm Runoff 430 mm 594 mm 764 mm Rainfall Loddon- Avoca Campaspe Goulburn-Broken

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SLIDE 24

Current development & historic climate

  • Goulburn-Broken
  • Current use 92 GL/yr; 10% of total water use
  • 87% from Shepparton WSPA (moderate level of development)
  • Other GMUs at low level of development
  • Eventual impact on streamflow: 20 GL/yr
  • Campaspe
  • Current use 30 GL/yr; 9% of total water use
  • 88% from Campaspe Deep Lead GMU (moderate level of development)
  • Other GMUs at low level of development
  • Eventual impact on streamflow: ~3 GL/yr (uncertain)
  • Loddon-Avoca
  • Current use 29 GL/yr; 9% of total water use
  • 64% from Mid-Loddon GMU All GMUs at medium level of development
  • Eventual impact on streamflow: 5.4 GL/yr
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SLIDE 25

Current development & historic climate

  • Goulburn-Broken
  • Average period between large beneficial floods to the lower Goulburn

floodplain has increased >4x.

  • Undesirably low flows that diminish deep water pools and degrade native fish

habitat are now more prevalent – occurring about twice a year on average rather than once every 7–8 years.

  • Campaspe
  • The period between, beneficial winter–spring bankfull flow events in the lower

Campaspe River has increased, and event size has been reduced.

  • Loddon-Avoca
  • The average period between beneficial small winter floods along the lower

Loddon River has increased from 10 to 18 months. The average annual flooding volume of events has halved.

  • The percentage of months with undesirably low flows in the lower river during

winter–spring has increased from 21 to 31 percent. This has degraded native fish habitat with consequences for native fish populations

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SLIDE 26
  • CSIRO. MDB Sustainable Yields Project

Current development & recent (1997-2006) climate

  • Goulburn-Broken
  • Mean annual rainfall and runoff are 15 percent and 41 percent lower respectively
  • A long-term continuation would mean:
  • average surface water availability would be reduced by 41%
  • end-of-system flows on the Goulburn River at McCoy's Bridge would be reduced by 58%
  • volume of water diverted for use within the region would be reduced by 25%.
  • Campaspe
  • Mean annual rainfall and runoff are 13 percent and 50 percent lower respectively
  • A long-term continuation would mean:
  • average surface water availability would be reduced by 54%
  • end-of-system flows on Campaspe River at Echuca would be reduced by 76%
  • volume of water diverted for use within the region would be reduced by 26%.
  • Loddon-Avoca
  • Mean annual rainfall and runoff are 11 percent and 52 percent lower respectively
  • A long-term continuation would mean:
  • average surface water availability would be reduced by 50%
  • total end-of-system flows would be reduced by 71%
  • volume of water diverted for use within the region would be reduced by 28%.
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SLIDE 27
  • CSIRO. MDB Sustainable Yields Project

Future climate & current development

  • 6 to -63 (-27)
  • 10 to -69 (-27)
  • 6 to -62 (-22)

EOS flow change (%) 0 to -40 (-6) 0 to -28 (-5)

  • 1 to -30 (-6)

Water diverted within region change (%)

  • 5 to -49 (-18)
  • 4 to -46 (-16)
  • 3 to -45 (-14)

Water availability change (%) 0 to -43 (-16)

  • 4 to -46 (-16)
  • 2 to -44 (-13)

Runoff change (%) Loddon-Avoca Campaspe Goulburn-Broken

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SLIDE 28

Future climate & current development

  • Goulburn-Broken
  • Best estimate 2030 climate: substantial reductions in the occurrence and volumes of flooding of

the lower river floodplain. Occurrence of undesirably low flows would increase slightly.

  • Dry 2030 climate extreme: similar hydrological changes and ecological consequences as a

continuation of the recent climate. Wet 2030 climate extreme: little change from current conditions for flooding of the lower river floodplain. Occurrence of undesirably low flows would increase slightly.

  • Campaspe
  • Best estimate 2030 climate: average period between winter–spring bankfull flows in the lower

river would increase by nearly one year (44%); maximum period between these events would increase by about two years (21%). The average annual overbank volume would be reduced by 37 percent. These changes would be likely to have substantial ecological consequences.

  • Wet 2030 climate extreme: average and maximum period between winter–spring high bankfull

flows would be increased and overbank flood volumes would be reduced. Dry 2030 climate extreme would lead to changes in environmentally important flows that would be very similar to under a continuation of the recent climate.

  • Loddon-Avoca
  • Best estimate 2030 climate: average period between ecologically beneficial small winter floods

would not change greatly. Floods would be smaller such that the average annual volume would be reduced by 32%. Undesirably low flow conditions that degrade fish habitat would occur in 37% of winter–spring months.

  • Dry 2030 climate extreme: similar to a continuation of the recent climate. Wet 2030 climate

extreme conditions would be similar to those under the historical climate and current development.

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SLIDE 29

Future climate & future development

36% (32%) 44% (36%) 55% (50%) Best estimate level of SW use (cf current) 17 GL/yr 6 GL/yr 37 GL/yr Total streamflow impact 103% 10% 67% GW use increase ~1% 1.5% <1% Runoff reduction 3% 8% 8% Farm dam capacity increase Loddon- Avoca Campaspe Goulburn- Broken

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SLIDE 30

Goulburn-Broken Scenario summary – water availability and use

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SLIDE 31

Campaspe Scenario summary – water availability and use

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SLIDE 32

Loddon-Avoca Scenario summary – water availability and use

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SLIDE 33

High and Low Reliability Water Shares

Goulburn Broken Campaspe Loddon Current 97% 88% 99% 92% Recent 49% 52% 77% 47% Future 87% (33-95) 83% (54-86) 97% (83-98) 83% (32-91) Current 73% 1% 76% 58% Recent 8% 1% 8% 1% Future 29% (4-54) 1% (1-1) 33% (13-43) 15% (1-47) Min HRWS February allocation Years (%) with max HRWS allocation Goulburn Broken Campaspe Loddon Current 42% 84% 74% 42% Recent 88% 47% 46% 88% Future 21% (1-36) 79% (49-81) 67% (37-71) 21% (1-36) Current 24% 11% 10% 24% Recent 2% 48% 24% 2% Future 36% (93-27) 17% (45-14) 17% (33-17) 36% (93-27) Years (%) with max LRWS allocation Years (%) with zero LRWS allocation

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SLIDE 34

www.csiro.au/mdbsy

Murray-Darling Basin Sustainable Yields Project

funded under the

Raising National Water Standards Program

  • f the

National Water Commission