Queensland Lake Eyre and Bulloo Freshwater Biogeographic Province

Queensland Lake Eyre and Bulloo Freshwater Biogeographic Province – Hydrology

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Gauges

Modelled pre-development data from 5 gauges were used for these analyses.

Gauging stations used in calculation of the Lake Eyre and Bulloo FBP hydrological features

002101B

002104A

003101A

003103A

003202A

Base flow and flood flow

On average base flow only accounts for 9% of flow volume, whilst the other 91% is directly related to flood flow from rainfall events.  The difference was most pronounced at the Quilpie gauging station where only 5% of flow was base flow. 

 

Information about hydrology

Information about methods

 

No-Flow Spells	Mean	SE	Max	Min
Base Flow Index	0.088	0.016	0.14	0.050
Flood Flow Index	0.91	0.016	0.95	0.86

Magnitude of spates

Due to the large sizes of the catchment areas and the strong bias to extremes of flow, spates result in very low run-off values at 0.002 Ml km² day^-1. The FBP has a wide amount of variability in spate number, ranging from 2.3 to 3.3 spates per year.  These spates are distributed relatively evenly between the wet and dry seasons.  On average the wet season has 1.3 – 2.1 spates whereas the dry season has 1.1 – 2.3.  The average duration of spates is also quite variable, ranging from 11 to 27 days on average. 

 

Information about magnitude of spates

Information about methods

 

Magnitude of spates	Mean	SE	Max	Min
Spate run-off (Ml km2 day-1)	0.002	0.000	0.004	0.001

 

Frequency and duration of spates	Mean	SE	Max	Min
Mean number of spates per year	3.28	1.0020	6.11	0.75
Mean duration of spates (days)	19.19	7.83	49.15	6.063
Mean number of wet season spates per year	1.72	0.38	2.88	0.61
Mean number of dry season spates per year	1.73	0.60	3.37	0.43

 

No flow spells

On average a single no-flow spell lasts for 84 days and sites in the FBP have 2 - 3 per year.  Duration of no-flow spells range from approximately 65 - 105 days with a similar period of time separating the spells.  

It should be noted that some of the variability in the presented facts is probably due to the low number of gauging stations affecting confidence in the results. 

 

Information about no flow spells

Information about methods

 

No-Flow Spells	Mean	SE	Max	Min
Frequency of No Flow Spells (spells per year)	2.76	0.61	4.32	1.18
Proportion of time with no flow (%)	0.52	0.033	0.64	0.47
Longest No Flow Spell (days)	523.60	90.77	752	235
Mean Duration of No Flow Spells (days)	84.47	19.32	144.87	42.52
Mean period between No Flow Spells (days)	83.64	23.83	171.40	41.69
Longest period between No Flow Spells (days)	523.60	90.77	752	235

Rise and fall of the hydrograph

The mean rate of rise for the FBP is approximately double the mean rate of fall.  The averages for the greatest rates of rise and fall were roughly equal.  

 

Information about hydrology

Information about methods

 

Rise and fall of the hydrograph (per day relative to the mean daily flow)	Mean	SE	Max	Min
Mean rate of rise	1.53	0.35	2.61	0.66
Greatest rate of rise	50.75	10.28	89.60	33.42
Mean rate of fall	0.77	0.30	1.94	0.23
Greatest rate of fall	50.016	25.80	152.23	15.18

Wet and dry seasons

The proportion of annual flow is not distributed evenly between months.  The months January to April have a much greater proportion of annual flow than May to December.  Based on this the wet season for the Lake Eyre and Bulloo FBP is January to April and the dry season May to December. 

 

Information about hydrology

Information about methods

 

 

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Last updated: 22 March 2013