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

7 Figure 1. When flow exceeds 15.2 cumecs, the river becomes essentially continuous (critical depth 0.5 m see text of full report). Figure 1. Degree of fragmentation on the Daly River (between Dorisvale Crossing and Cattle Creek) as a function a function of flow. Flow is as measured at Dorisvale Gauging Station. Modelling Water Temperatures Alterations to equilibrium water temperatures arising from flow reductions in the dry season are predicted to be very modest, less than 1.0 0C, driven primarily by water depth which does not change dramatically during the dry season. We did not model the impact of reduction in water depth below cease-to-flow conditions. The largest impact of flow on water temperature of up to 2.0oC occurred between Dorisvale Crossing and Station 10 (Hot Spring), but this arose because the water entering the study stretch was in disequilibrium (2.0oC lower than equilibrium), causes unknown. Background temperatures in the river varied over the 58-day study by about 4.0 0C and these are clearly related to meteorological conditions. Large changes to the temperatures or volumes of the major springs flowing into the Daly River could have a major impact on its temperature. Synopsis and Recommendations Table 1 is an integrated analysis of the impact of flow reduction on the life history of the pignosed turtle. It shows the outcome for each of several flows, which we have classified as boom or bust.