Territory Stories

Modelling dry season flows and predicting the impact of water extraction of flagship species



Modelling dry season flows and predicting the impact of water extraction of flagship species


Georges, Aurthur; Webster, Ian; Guarino, Fiorenzo; Jolly, Peter; Thoms, Martin; Doody, Sean; CRC for Freshwater Ecology (Australia); University of Canberra. Applied Ecology Research Group


E-Publications; E-Books; PublicationNT; 57/2002; National River health program




Daly River


The aim of this project is to contribute to recommendations on environmental flows to ensure that they are consistent with maintaining the biota of the Daly River, given competing demands of agriculture, recreation and tourism, conservation and Aboriginal culture. Our focus is on flow, connectivity and water temperatures.


Made available by via Publications (Legal Deposit) Act 2004 (NT); Submitted to the Northern Territory. Department of Infrastructure Planning and Environment

Table of contents

1. Project Details -- 2. Executive Summary -- 3. Interpretation of the Brief -- 4. Variation of the Brief -- 5. Background -- 6. The Daly Drainage -- 7. The Pig-nosed turtle -- 8. Analysis of Historical Flow Data -- 9. Analysis of Contemporary Flow Data -- 10. Modelling Flow Reduction -- 11. Water Temperature Versus Flow -- 12. Impact on Flagship Species -- 13. References




Environmental Flows; Modelling; Biota

Publisher name

Northern Territory Government

Place of publication



Final Report


57/2002; National River health program


75 pages ; 30 cm

File type



Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



Parent handle


Citation address


Page content

20 Flow Characterization Average Monthly Flows The highest median flow occurs in February followed by March. The lowest median flow occurs in October followed closely by August and September. Indeed, a low-flow state typically occurs in all months from June through to November if median flow is the consideration (Figure 4). A similar picture emerges with the mean flows, but the mean is more greatly influenced than the median by the few extreme high flows. The highest monthly mean flow occurred in March. Full summary statistics for flow are presented in Tables A1 and A2 of Appendix 1. Monthly flow varies considerably across years while remaining consistent with the overall wet-dry pattern. This inter-annual variability derives from variation in both the magnitude and the timing of the wet season rains and associated discharge. Figure 4. Median and mean flow by month for the Dorisvale gauging station (G8140067), Daly River, Northern Territory. Median flows were calculated from the raw daily heights. Mean flows were calculated first as a mean for each month, then averaging the monthly mean flows across years. In both cases, data from months where there were less than 20 gauged days were excluded. Flow Category by Month The frequency of occurrence of the categories of flow conditions across months is shown in Figure 5. Months can be grouped into four classes. January to March have flows dominated by High to Extremely High flows with very poor representation of years with Low or Extremely Low flows in these months. June to October have flows dominated by Low to Extremely Low flows with no occurrences of High or Extremely High flows in these months for any year. April and December are similar in the flow categories likely to occur in those months, though of course April is on the transition between high-flow and low-flow conditions, and December is on the transition between low-flow and high-flow conditions. Both months are dominated by Transitional and High Flows with the rare occurrence of an Extremely High flow (Figure 5).