2019- 20 Lake Cargelligo 18 Feb 2020 Recent Rainfall 10-2-20 - - PowerPoint PPT Presentation

Lachlan River Operations 2019- 20

Lake Cargelligo 18 Feb 2020

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Recent Rainfall

10-2-20 24hrs 9-2-20 24hrs

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Recent rain hydrographs

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Period 9 Day 09/02/2020 to 18/02/2020 2020 412066 ABERCROMBIE HADLEY 2 141.00 Discharge (ML/d) PROV 41200209 ABERCROMBIE @ ABER#2 141.00 Discharge (ML/d) PROV 20000 40000 60000 80000 100000 10000 20000 30000 40000 50000 9 10 11 12 13 14 15 16 17

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Recent rain hydrographs

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Period 9 Day 09/02/2020 to 18/02/2020 2020 412065 LACHLAN @ NARRAWA 141.00 Discharge (ML/d) PROV 412050 CROOKWELL NARRAWA N. 141.00 Discharge (ML/d) PROV 412027 LACHLAN @ REIDS FLAT 141.00 Discharge (ML/d) PROV 4000 8000 12000 16000 20000 50 100 150 5000 10000 15000 9 10 11 12 13 14 15 16 17

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Recent rain hydrographs

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Period 9 Day 09/02/2020 to 18/02/2020 2020 412067 LACHLAN D/S WYANGALA 141.00 Discharge (ML/d) PROV 412175 HOVELLS CK @ NO.2 141.00 Discharge (ML/d) PROV 412029 BOOROWA PROSSERS XNG 141.00 Discharge (ML/d) PROV 412002 LACHLAN R @ COWRA 141.00 Discharge (ML/d) PROV 200 400 600 800 1000 1200 250 500 750 1000 1250 50 100 150 200 250 300 200 450 700 950 1200 1450 9 10 11 12 13 14 15 16 17

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Current Storage Status

• Wyangala: as at 17/02/20
• Storage Volume: 155,032 ML
• Storage Percent: 12.7%, increase of 4.3% from 8.4% on 10 Feb
• System Inflows since 1July19 – 31 Jan 20: 9,700 ML
• System Inflows since 1 Feb 20 – 9 Feb 20: 4,000 ML (2 GL + 2 GL)
• System Inflows since 10 Feb 20 – 17 Feb: 58,000 ML (55 GL + 3 GL)
• Lake Cargelligo:
• Storage Volume: 23,898 ML (17 Feb 20)
• Storage Percent: 58.1%
• Projected Volume: 28,261 ML (1 March 20)
• Projected Percent: 72%

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7

36 month rainfall deficiency

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8

NSW temperatures

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Soil moisture deficiencies

August 2019

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Comparison of Drought inflows

• Aug 2017 – Jan 2020 (30 months) actual dam inflows = 256 GL
• Aug – Jan 30 months pre 2004 DOR inflows = 509 GL (year 1947)
• Aug – Jan 30 months millennium DOR inflows = 259 GL (year 2005)

100 200 300 400 500 600 700 800 5 10 15 20 25 30 35 40 Cumulative Inflows in GL No of Months

Wyangala Drought Inflows for 36 Months Starting in August

Aug 1979 - Jul 1982 Aug 2001 - Jul 2004 Aug 2007 - Jul 2010 Aug 2017 - Jan 2020 (30 months) Drought of Record Aug 1944 - Jul 1947

252 GL Deficit in inflows

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Assumptions:

• Zero inflows
• Water savings 15 GL in

2019-20

• 2020-21under IRG 3

Essential Requirements – 130GL

• GS under usage – 10 GL
• WQA – 1GL
• No S&D replenishment
• Lake Cargelligo Offline

March 2020

End January 2020 assessment

4.2% 1.6%

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End January 2020 assessment

Comparison combined inflows – recent years

50 100 150 200 250 300 350 Combined Cumulative Inflows in GL

Actual Combined Inflows Vs Minimum Combined Inflows starting July 2019

Pre 2004 Combined Inflows for 57% GS access Inflows from 1 July 19 2018-19 Combined Inflows 2017-18 Combined Inflows

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LC Storage by end of March 20

20% 30% 40% 50% 60% 70% 80% 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1-Jan 1-Feb 1-Mar

Storage Percent

Storage Forecast

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Wyangala Dam Behaviour during Millennium Drought 2003-2010

0% 5% 10% 15% 20% 25% 30% 35% 40% 45%

50000 100000 150000 200000 250000 300000 350000 400000 450000 01-Jul-03 01-Jul-04 01-Jul-05 01-Jul-06 01-Jul-07 01-Jul-08 01-Jul-09 01-Jul-10

Wyangala Dam Storage Volume During Millennium Drought 2003 - 2010

Wyangala Volume (ML) Wyangala Level (%)

Supply Source Vs Resource Distribution

End Jan 20

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What Does it take to operate Lachlan River

• Transmission and Operation Loss

Regulated Lachlan River Transmission & Operations Losses Typical dry year (GL) Millennium Drought IRG stage 3 drought

• perations

IRG stage 4 drought

• perations

2004-05 2006-07 2008-09

Main regulated river from dam to Lake Cargelligo Weir

56 27 76 59 55 55

Wallamundry/Wallaroi/Nerrathong system

14 14 13 12 12 6

Replenishment flows into Booberoi Ck

12 7 7 6 6 3

Flows to Lake Cargelligo through emergency works for TWS & BLR

5 3 3 3 3

Losses in regulated Willandra Ck system

15 4 2 2 2

Losses LC Weir to Booligal

40 42 47 40 39 20

Target Flows required below Booligal

13 15 15 14 13 6

Replenishment Flows into Willandra Creek

9 5

Replenishment Flows into Merrowie Creek

9

Replenishment Flows into Merrimajeel/Muggabh Creek

7

Operational Surplus

5

Total

180 118 163 135 130 95

Drought Contingency Measures - Current

• Reduction to access - remaining GS (57%) and HS (87%) allocations
• Cutdown flows in regulated sections to minimise transmission losses (Willandra Creek)
• Reduced flows in regulated sections to minimise incremental losses (Wallamundry

System)

• Reduced End of System Targets
• Booberoi Creek flows assisted by delivery of environmental water
• Conservative use of WQA
• Take Lake Cargelligo offline
• No delivery of S&D Replenishment from Wyangala

Drought Contingency Measures – Potential

• Further reduction to access remaining GS after 31 March 20
• After 31 March, normal delivery of remaining HS allocations to Condobolin,

but only critical human needs d/s of Condobolin

• Continue cease to flows in Willandra Creek
• Reduced flows in Wallamundry System, deliver flows in one of the creeks.
• Control inefficiencies in extraction of BLR
• Above measures and others will be discussed in ROSCCo next week

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LC Work Approval Locations

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LC Usage

2018-19 Orders Usage Lake Cargelligo Storage 21.5 45.1 DOMESTIC AND STOCK [STOCK] LOCAL WATER UTILITY REGULATED RIVER (GENERAL SECURITY) 15.5 43.4 REGULATED RIVER (HIGH SECURITY) 6 1.7 2017-18 Orders Usage Lake Cargelligo Storage 100 149.6 DOMESTIC AND STOCK DOMESTIC AND STOCK [DOMESTIC] 2.2 DOMESTIC AND STOCK [STOCK] LOCAL WATER UTILITY 55 50.8 REGULATED RIVER (GENERAL SECURITY) 45 96.6 REGULATED RIVER (HIGH SECURITY)

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LC Water Supply Emergency Works

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25% chance 17 Feb to 1 Mar 50% chance 17 Feb to 1 Mar

Climate Outlook

• End of Presentation