Water Security in NSW May 2019


Recent State Government announcements have expressed concern over potable water supplies for Cobar, Tenterfield, Orange, Tamworth and Guyra. Collectively, this water shortage is trending towards an unsustainable situation based on the current distribution system and changing rainfall patterns.

Global Perspective

To place this increasingly serious water supply situation into a wider context, reference is made to ‘State of Climate 2018’ by the Bureau of Meteorology. Summarised below are facts relating to the global trends:

  • Carbon dioxide concentrations have now risen above 405 ppm and are increasing at more than 2.5 ppm per year.
  • The addition of methane and nitrous oxide raises the carbon equivalent concentrations to 500 ppm.
  • Emissions from fossil fuels are still rising.
  • Global sea level has risen by 20-25 centimetres since 1880, the rate is increasing due to increasing melt rates from Antarctica and Greenland.
  • Ocean waters are becoming increasingly acidic.

The Australian Picture

The global changes are now reflected in irascible weather patterns over south-east Australia. This concerning situation has prompted a report by NSW Local Land Services titled ‘Climate Change in Central West New South Wales’. Principal points in this report are:

  • Australia’s climate has warmed by 1°C since 1910.
  • The frequency of extreme weather events has increased.
  • Nine of the ten warmest years on record have occurred since 1998.
  • Over south eastern Australia, autumn and winter rainfall has mostly been below average since 1990, leading to imperceptible ‘drying out’ and declining river flow.
  • Extreme fire weather has increased over the past fifteen years with wild fires increasing in intensity and unpredictability.

NSW Central West Region

Based on historical trends modelling for the Central West and adjacent region indicates:

  • In addition to the 1°C rise, temperature will increase by 0.7°C by 2030 and by 2.1°C by 2070.
  • Rising overnight summer temperatures will cause increasing discomfort. Energy demands, costs and greenhouse gas emissions will increase with air conditioner use.
  • Heat wave conditions will substantially increase above 35°C towards 2030 by an extra 10-20 days while, by 2070, there will be an extra 30-40 days around or exceeding 45°C.
  • Rising livestock and native fauna loss is to be expected due to a reduction in water resources.
  •  There has been a 15% decline in average autumn and winter rainfall over south east Australia, however, the relationship to the anthropogenic era has not yet been established. (BOM/CSIRO 2014)
  • Rainfall-modelling forecasts there will be a slight increase in spring rainfall but an increase in summer/autumn rainfall will be due to storm cells causing hail, wind and flash flood damage.
  • Annual evaporation, currently 1.8 meters at Dubbo, will increase across the region.
  • With increased temperatures, evapotranspiration and changing rainfall patterns, there has been a global trend of landscape drying. Anecdotal hearsay is that landscape drying is occurring over much of New South Wales.

Drought and Water Security in New South Wales.

The Department of Primary Industry has defined the current drought as the most severe on record with the Central West, Far West and North West regions the worst affected. These conditions extend into Queensland. The severity can be judged by the extremely low valley storage levels. Readings in May 2019 were Lower Darling – 1%, Namoi – 2%, Border Rivers – 7%, Gwydir – 10% and Macquarie – 12%.

The prognosis is that El Niño conditions are set to continue. With this information, the water resources and the long-term viability, at this stage, for five New South Wales towns, aggregating some 85,000 people, is a concerning social issue. Over the coming period each town, Cobar, Tenterfield, Orange, Tamworth and Guyra will be discussed with reference to current and future water storage, river potential, borehole water and pipeline delivery. The backdrop is the slow drying of the landscape.

Agricultural Adjustment

Trends indicate current weather patterns will intensify and morph into a more violent drier climate. Historical farming practice in New South Wales will have to adjust. The drip irrigation system developed by Israel may be applicable with modification to Australia’s drying landscape: markets to Asia may be generated by this change. Cereal production will decline but as the dry hot Queensland climate moves south into New South Wales, Brahmans will tend to replace current cattle breeds.

Drought hits Australian Wheat Supplies

See illustration next page (Geopolitical Futures, 24 May 2019)

Note declining wheat area and production – drought or climate change?

Source – Geopolitical Futures  24 May 2019

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