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Hydrology
Gauges
Photo: Bulloo River - DERM Modelled pre-development data from 52 gauges within the Central FBP were used for these analyses. Key features of typical hydrographs over multiple temporal scales were used to characterise the following aspects.
Base flow and flood flowOn average approximately 9% of flow (by volume) is base flow and conversely 91% of flow is related directly to flood flow from rainfall events. Over 30% of flow was base flow at one site in the Pioneer catchment, while flood flow contributed 97% of total flow volume at one site in the Burdekin catchment.
Magnitude of spates
Photo: Bowen River - DERM
Photo: Teemburra Creek - DERM Magnitude of spates averaged 0.4 to 0.6 ML km2 day-1, but much larger and smaller average values occur within the province at particular sites. There is an average of 3 to 4 spates per year, with approximately two occurring during the wet season and one during the dry season. The average duration of spates is approximately 11 to 12 days.
Information about magnitude of spates
No flow spells
Photo: Teemburra Creek - DERM Flow can generally be considered to be intermittent in the Central province. Each of the 52 modelled sites experienced periods without flow. However, some sites in the Burdekin and Pioneer catchments had natural flow regimes that were nearly perennial, with very few no flow periods in the record. Sites in the province on average had 3 - 4 no flow spells per year lasting on average 29 days each. The average longest recorded spell was over 8 months, but this was as high as almost 2 years at one site in the Burdekin catchment and as low as only 22 days at one site in the Pioneer catchment. Sites in the province had no flow on average approximately 30% of the time, but this varied from only 0.3% of the time at a site in the Pioneer catchment to nearly 90% of the time at a site in the Burdekin catchment. Periods of flow between no flow spells typically lasted approximately 10 months, both the longest (32 years) and shortest (3 months) periods with continual flow occurred in the Burdekin catchment. When averaged across the gauges the longest period of continual flow was 6.25 years for the entire province. Persistent waterholes are the most evident form of drought refugia in the Central province. Another possible source of refuge in the province is migration into sub-surface water in the form of shallow alluvial aquifers. There is evidence of such migration occurring in this province, a study found 50 invertebrate taxa in hyporheic and parafluvial shallow alluvial aquifers. Many of these were thought to be individuals of surface species that had moved into the aquifer (Hancock, 2004).
Information about no flow spells
Rise and fall of the hydrograph
Photo: Pelican Creek- DERM
Table: Rise and Fall of the Hydrograph per day relative to mean daily flow
Wet and dry seasonsThe proportion of annual flow is not evenly distributed between months. The months January to April have a greater proportion of annual flow than if flow were evenly distributed, and the months May to December a smaller proportion. Based on this the wet season for the Central FBP is January to April and the dry season May to December. Compare this with the other provinces.
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— Department of Environment and Resource Management
Science and Research → Wetland Conceptual Models → Riverine → Freshwater Biogeographic Provinces → Central → Hydrology
