Annual Water Outlook 2021 DOCUMENT CONTROL
Total Page：16
File Type：pdf, Size：1020Kb
WANNON WATER Annual Water Outlook 2021 DOCUMENT CONTROL Report Template - Business Support Custodian Planning & Development Professional Approver Branch Manager Asset Planning Status Approved Version 1 Approved Date 1/11/2020 Review Due Date 30/10/2021 © Wannon Region Water Corporation PO Box 1158 Warrnambool 3280 2 | P a g e Contents 1 Introduction ................................................................................................................... 5 2 Region overview ............................................................................................................ 5 Supply systems summaries .................................................................................... 6 Water consumption overview 2020 ......................................................................... 7 3 Climate outlook ............................................................................................................. 8 Rainfall outlook ....................................................................................................... 8 Temperature outlook ............................................................................................... 9 Streamflow outlook ............................................................................................... 10 El Niño–Southern Oscillation (ENSO) outlook ....................................................... 10 4 Water supply systems outlooks ................................................................................... 10 Otways System ..................................................................................................... 10 4.1.1 System summary .................................................................................. 10 4.1.2 Water demand summary ...................................................................... 11 4.1.3 Storage levels and 2021 outlook .......................................................... 12 Grampians System ............................................................................................... 14 4.2.1 System summary .................................................................................. 14 4.2.2 Supply and demand graphs .................................................................. 14 4.2.3 Storage levels and 2021 outlook .......................................................... 15 Glenthompson System .......................................................................................... 17 4.3.1 System summary .................................................................................. 17 4.3.2 Water demand summary ...................................................................... 17 4.3.3 Storage levels and 2021 outlook .......................................................... 18 Groundwater systems ........................................................................................... 20 4.4.1 System summary .................................................................................. 20 4.4.2 Security of groundwater supply ............................................................ 20 3 | P a g e List of Figures Figure 1 - Wannon Water Region .......................................................................................... 5 Figure 2 - Water consumption (ML) by segment 2019-20 ...................................................... 7 Figure 3 - Water Consumption & NRW breakdown (ML) ....................................................... 8 Figure 4 - Victoria's climate trend since 1950 (Victoria State Government 2015)................... 8 Figure 5 - Bureau of Meteorology rainfall outlook, December 2020 – February 2021 ............ 9 Figure 6- Bureau of Meteorology temperature outlook, December 2020 – February 2021 .... 9 Figure 8 - Bureau of Meteorology ENSO outlook September 2020 ..................................... 10 Figure 8 - Otways System Summary ................................................................................... 11 Figure 9 - Otways System Usage verses 2017 UWS Demand Projections .......................... 12 Figure 10 - Otways System Storage Level Outlook ............................................................. 13 Figure 11 - Otways System Achievements and Actions ...................................................... 13 Figure 12 - Grampians System Summary ........................................................................... 14 Figure 13 - Grampians System Usage verses 2017 UWS Projected Demands ................... 15 Figure 15 - Grampians System Achievements & Actions .................................................... 16 Figure 16 - Grampians System Storage Levels and Outlook ............................................... 16 Figure 16 - Glenthompson System Summary ...................................................................... 17 Figure 17 - Glenthompson System Demand verses 2017 UWS Forecasted Demands ....... 18 Figure 19 - Glenthompson Storage Levels and 2021 Outlook ............................................. 19 Figure 19 - Glenthompson Achievements and Actions ........................................................ 19 Figure 20 - Groundwater Systems Summary ...................................................................... 20 Figure 21 - Groundwater Usage verses Capacity (2019-2020) ............................................ 20 List of Tables Table 1 - Water supply systems and towns supplied ............................................................. 6 4 | P a g e 1 Introduction This Annual Water Outlook has been prepared, as required under Part 4-2 of the Statement of Obligations (General) 2015. It is prepared to inform our customers, stakeholders and the community on: a. the current water resource position b. the outlook for our water resources over the coming year under a range of plausible climatic scenarios c. ability to meet agreed levels of service; and d. actions to improve system performance, if required, to meet agreed levels of service. 2 Region overview The regional map (Figure 1) displays all of the customer service zones within Wannon Water and the services provided to each particular zone. It includes the major centres of Warrnambool, Portland and Hamilton. Figure 1 - Wannon Water Region 5 | P a g e Supply systems summaries Wannon Water supplies drinking water to an estimated population of 89,000 people, which is divided into 34 drinking water localities and various non-drinking water regions. Our water supply comes from a diverse range of water sources, including surface water catchments, deep geothermal and shallow groundwater aquifers. A breakdown of water sources for each locality is represented in Table 1. Table 1 - Water supply systems and towns supplied Supply (transfer) measures Likelihood of Water system Supply sources Towns supplied planned for dry restrictions for 2021 scenario (to December 2021) Otways Arkins Creek Allansford Very rare (<1%) None catchment Camperdown Gellibrand Cobden River Derrinallum catchment Glenormiston Supplemented Koroit by groundwater Lismore and roof water. Mortlake Noorat Purnim Simpson Terang Warrnambool Grampians Little Tea Tree Balmoral Very rare (<1%) None Creek and Cavendish Glenelg River Dunkeld tributaries Hamilton (Grampians Tarrington National Park) Rocklands Reservoir Glenthompson Yuppekiar Glenthompson Very rare (<1%) 20 ML transferred Creek through Willaura Mt William pipeline Creek Grampians bores Groundwater Otway lower Portland Very rare (<1%) None systems aquifers Port Fairy Bridgewater Heywood formation Dartmoor aquifer Macarthur Newer volcanic Port Campbell aquifers Peterborough Timboon Casterton Coleraine Sandford Merino Penshurst Caramut Darlington Konong- Den Hills Creek None (rural N/A None wootong customers only) 6 | P a g e Water consumption overview 2020 Our customer water usage for the 2019/20 period was 11,480 megalitres, which is broken down into demand type in Figure 2. Figure 3 shows the long-term customer demand trend over the years as well as non-revenue water trends. Non- revenue water is water lost through leaks, bursts and water theft. Water usage has been fairly consistent for our service region. Figure 2 - Water consumption (ML) by segment 2019-20 7 | P a g e Figure 3 - Water Consumption & NRW breakdown (ML) 3 Climate outlook Weather and climate are the primary influences on Australia’s water resources. Extreme storms produce floods that can rise and fall within hours or that can last for months, while yearly variability in rainfall can produce droughts that may last for extended periods. According to Commonwealth Scientific Industrial Research Organisation (CSIRO) and Bureau of Meteorology (BoM), Victoria's climate has shown a warming and drying trend since the 1950s (Figure 4). This trend is expected to continue into the long-term future and will be felt most during summer periods when water use is at its highest demand. We monitor rainfall and stream flow outlooks to make informed decision on water supply based on the most up to date information provided by BoM at: Figure 4 - Victoria's climate trend since 1950 (Victoria http://www.bom.gov.au/climate/ahead/ State Government 2015) Rainfall outlook The latest BoM rainfall outlook (issued on 19 November 2020) indicates that rainfall in our region is expected to have a 60% chance of exceeding the median rainfall between December 2020 and February 2021. 8 | P a g e Figure 5 - Bureau of Meteorology rainfall outlook, December 2020 – February 2021 Temperature outlook The temperature