Download PRESENTATION TITLE - Planning Institute Australia

Planning ACT’s Water Supply
for Climate Change
Kirilly Dickson
Sustainability Advisor
September 2006
1
• When is a new supply likely to be
needed?
– Report December 2004
• Where would be the best place to get it?
– Report April 2005
• Ongoing Work post April 2005
2
Water Supply Planning Key Variables
1.
2.
3.
4.
5.
6.
3
Climate change
Bushfire recovery
Population growth (NSW supply)
Demand management
Water Restrictions
Environmental flows – under review
What will happen?
• CSIRO, 2003
• 20% reduction in
runoff
• temp increase by
0.4 to 1.6 deg C by
2030,
• higher evaporation
4
Supply - How we used this?
• Generated a stochastic 2030 climate change
data sequence
• Used variability & skewness of entire 133 yrs
of historic record
• Average rainfall and evaporation since 1976
but adjusted to account for reduced rainfall
and increased evaporation as per CSIRO
projections
5
Water supply
1400000
1200000
Annual Inflow (ML)
1000000
800000
600000
400000
200000
0
0%
10%
20%
30%
40%
50%
60%
70%
80%
Percentile (equalled or exceeded)
Historic
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Climate Change(2030) Stochastic
Current Climate(1990) Stochastic
90%
100%
Supply
7
Demand – how we used this?
• Built a new demand model
• Generated 10,000 years of monthly
demands
• Based on 2030 stochastic rainfall and
evaporation sequences
8
Water demand
350
Annual Demand (kL/capita)
300
250
200
150
100
0%
10%
20%
30%
40%
50%
60%
Percentile
Historical
9
1990 climate
2030 climate
70%
80%
90%
100%
Other effects - bushfires
Corin Stream Flow
Bendora Stream Flow
Cotter Stream Flow
Bushfire Potential - catchment antecedent condition test
Season: January or February
Fuel Load: No fire event in the preceeding 19 years
Catchment Dryness: Sum of preceeding 3 and 6 month stream flow volumes
must not exceed defined flow thresholds.
3 month sum (ML)
6 month sum (ML)
Corin
2150
13500
Bendora
1550
10800
Cotter
800
5950
If antecedent condition test true
10% chance of ignition
If antecedent condition test true and
bushfire triggered
50% chance of bushfire spreading
to adjacent catchment(s)
Apply Yield Reduction Curve
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Other effects - bushfires
Current
climate
stochastic
(Yr. 1990)
Climate
change
Stochastic
(Yr. 2030)
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Corin
Bendora
Cotter
No. of bushfire potential seasons
998
1072
981
% bushfire potential seasons
10%
11%
10%
No. of triggered bushfires
132
137
111
Average Recurrence Interval of
bushfire events
76
73
90
No. of bushfire potential seasons
1425
1674
1399
% bushfire potential seasons
14%
17%
14%
No. of triggered bushfires
159
190
178
Average Recurrence Interval of
bushfire events
63
53
56
Sim
Overall impact
15%
Time in Restrictions
10%
This line shown in Figure 2
5%
0%
2000
2005
2010
2015
2020
2025
2030
Scenario Year
12
Prudent Planning Scenario
Low Population Growth
Low Population Growth, No CBS, No Climate Change (Lower Bound)
Medium Population Growth
Low Population Growth, No CBS
Medium Population Growth, 12.5% Maximum Demand Reduction
2035
Is it happening?
1200
3 Reservoirs Inflow
1000
Median 1871 - 1994 (167 GL/y)
Median 1994 - 2005 (87 GL/y)
Median 1901 - 1910 (88 GL/y)
GL/annum
800
1871 - 1911 are
simulated inflows
600
400
200
Corin + Bendora + Googong Inflows 1871 - 2004
13
2003
1999
1995
1991
1987
1983
1979
1975
1971
1967
1963
1959
1955
1951
1947
1943
1939
1935
1931
1927
1923
1919
1915
1911
1907
1903
1899
1895
1891
1887
1883
1879
1875
1871
0
Is it happening?
50000
30000
20000
10000
2 year moving average (ML/month)
5 Year moving average (ML/month)
2010
2000
1990
10 Year moving average (ML/month)
Moving Average Total Storage Inflows
14
1980
1970
1960
1950
1940
1930
1920
1910
1900
1890
1880
0
1870
ML/Month
40000
Is it worse than we think?
Change in Rainfall
Change in Evaporation
Predicted Predicted
Observed Predicted Predicted
Observed
Season Worst Case Best Case Modelled Since 2000 Worst Case Best Case Modelled Since 2000
Summer
-9%
12%
-8.9%
-5.7%
11.0%
0.5%
8.7%
2.0%
Autumn
-5%
5%
-4.9%
-41.8%
10.8%
0.8%
8.5%
5.4%
Winter
-11%
2%
-10.9%
-4.3%
12.8%
2.2%
10.5%
4.4%
Spring
-11%
0%
-10.9%
0.4%
12.0%
2.1%
9.7%
1.7%
Annual
-9%
2%
-9.0%
-11.8%
9.1%
1.4%
9.1%
4.1%
15
Thank you
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