National Water Account 2017

Fitzroy: Climate and water

  • High rainfall in July 2016 and March 2017 contributed to above-average rainfall for the year.
  • Ex-tropical cyclone Debbie impacted the region in March 2017, contributing to record monthly rainfall in eastern parts of the region.
  • Rainfall and streamflow for the remainder of the wet season was well below average.

For further information on the region's climate and water conditions during the 2016–17 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. There is a strong seasonality in rainfall patterns with most of the rain falling in the wet season (November–April). As a consequence, flow in the rivers is strongly seasonal. 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 2016–17 year

 

  • The total area-averaged rainfall for the year was 715 mm, more than the mean value of 663 mm.
  • In the first three months of year (July–September 2016), the climate was influenced by a negative Indian Ocean Dipole phase that is associated with higher winter–spring rainfall. Rainfall across much of the region was above-average during this 3-month period, which is typically the driest part of the year.
  • March rainfall was well above average due to heavy falls associated with ex-tropical cyclone Debbie; eastern parts of the region experienced record rainfall for the month.

 

 

Figure C2 Total monthly rainfall for the Fitzroy region during the 2016–17 year compared with the long-term average and percentiles for the region

 

  • Total rainfall in March was well above the 90th percentile and more than 3 times the March average.
  • Except for March, rainfall during the wet season months (November–April) was well below average.

 

Actual evapotranspiration


Figure C3 Annual and monthly actual evapotranspiration deciles for the Fitzroy region during the 2016–17 year

 

  • Total area-averaged actual evapotranspiration was 646 mm, more than the mean value of 597 mm.
  • The above average evapotranspiration may be attributed to a combination of above-average temperatures across the region and increased water availability, particularly following high rainfall during the first 3 months of the year (July–September) and March 2017.

 

 

Figure C4 Total monthly actual evapotranspiration for the Fitzroy region during the 2016–17 year compared with the long-term average and percentiles for the region

 

  • Actual evapotranspiration was below average for most of the wet season months (November–April) when water availability was low. This was due to relatively poor wet season rainfall up until March 2017.

 

Soil moisture

 


Figure C5 Annual and monthly soil moisture deciles in the root zone (0–1 m depth) for the Fitzroy region during the 2016–17 year

 

  • Soil moisture in the root zone (0–1m depth) was generally average to below average across the southern half of the region, and average to above average in the northern half of the region.
  • Rainfall and soil moisture are typically closely aligned. For example, below-average soil moisture during November–February can be attributed to the relatively poor wet season rainfall up until March 2017. The above-average soil moisture during April can be attributed to the well above-average rainfall that occurred during March 2017, particularly over the northeastern parts of the region.
  • 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 2016–17 year compared with the long-term average and percentiles

 

  • Streamflows were below average for most of the wet season, reflecting the relatively poor rainfall and soil moisture conditions experienced across the region during most of this period.
  • Heavy rainfall at the end of March 2017 associated with ex-tropical cyclone Debbie contributed to very high flows in March–April in the Isaac, Mackenzie, and Fitzroy rivers.
  • Streamflows during March-April in the Dawson, Nogoa and Comet rivers in the western part of the region were well below expected given the above average-rainfall in March. This is likely due to a combination of relatively poor antecedent soil moisture conditions in these catchment areas and less rainfall occurring over the inland parts of the region during March.
  • High flows in September 2016 in the Dawson River were due to very much above-average rainfall in the south-western part of the region.

 

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