National Water Account 2019

Fitzroy: Climate and water

  • Total annual rainfall was below average and the lowest since the 2002–03 year.
  • Streamflow during the wet season was well below average across the region.

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For further information on the region's climate and water conditions during the 2018–19 year scroll down this page or click on the links below:

 

About the region

  • The Fitzroy region has a sub-tropical, semi-arid climate with a high inter-annual variability in rainfall and streamflow.
  • Most of the rainfall occurs during the wet season (November–April). As a consequence, flow in the rivers is strongly seasonal and many of the region's rivers cease to flow during the dry season (May–October).

 

Climate conditions

Rainfall


Figure C1 Annual and monthly rainfall deciles for the Fitzroy region during the 2018–19 year

 

  • Total area-averaged rainfall for the year was 460 mm, well below the mean value of 659 mm.
  • The 2018–19 annual rainfall was the region's lowest since the 2002–03 year.
  • Annual rainfall was lower over the southern portion of the region. During December 2018–February 2019, typically the wetter months of the year, large areas in the south recorded their lowest rainfall on record for these months.
  • The above-average rainfall in March 2019 was a result of severe thunderstorms and showers that mainly impacted the inland parts of the region.

 

Figure C2 Total monthly rainfall for the Fitzroy region during the 2018–19 year compared with the average and percentiles for the region

 

  • Rainfall was above average in October 2018 and March–April 2019. All other months had below average rainfall.
  • Rainfall was well below average during December 2018–February 2019, the typically wetter months of the year.

 

Actual evapotranspiration


Figure C3 Annual and monthly actual evapotranspiration deciles for the Fitzroy region during the 2018–19 year

 

  • Total area-averaged actual evapotranspiration was below average across the entire region.
  • Evapotranspiration was below average during most months of the year due to the dry conditions and low water availability across the region throughout the year.
  • Above-average evapotranspiration only occurred across the region in November 2018 and April 2019 due to increased water availability following the higher rainfall in October 2018 and March 2019 respectively.

 

Soil moisture

 


Figure C5 Annual and monthly soil moisture deciles for the Fitzroy region during the 2018–19 year

 

  • Soil moisture in the root zone (0–1m depth) was below average across most of the region.
  • Rainfall and soil moisture are typically closely aligned. For example, well below-average soil moisture during December 2018–March 2019, particularly over the southern part of the region, is due to the poor rainfall that occurred over this area during the typically wetter months of the year (December–February).
  • The poor soil moisture conditions during July–September 2018 can be attributed to the well below-average rainfall that occurred during most of the 2018 dry season.
  • More information on soil moisture distribution across the Fitzroy region is available in the Australian Landscape Water Balance.

 

Streamflow responses

Streamflow


Figure C6 Key flow gauging stations along the main rivers within the Fitzroy region

 

  • The six main rivers in the region are the Fitzroy, Dawson, Nogoa, Mackenzie, Isaac, and Comet rivers, which correspond to the six sub-basins used for environmental water management (see the Water management section for more information).

 

 

Figure C7 Total monthly flow for key rivers during the 2018–19 year compared with the average and percentiles

 

  • Streamflows were below average for most of the year, which reflects the relatively poor rainfall and soil moisture conditions experienced across the region. For example, total annual flow in the Fitzroy River at the Gap (Station 130005A) was 1,334 GL compared to the average value of 5,057 GL.
  • Streamflows in the Dawson and Comet rivers during the typically wetter months between December 2018–March 2019 were very low. In the Comet River, no flow occurred during this period. This reflects the record low rainfall that occurred during this period across the upper reaches of these catchment areas in the southern part of the region.
  • In April 2019, streamflow in the Nagoa River was well above average, reflecting the higher rainfall that occurred during March–April 2019 over the upper reaches of this catchment area in the western part of the region.