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

45 The corresponding morphology for each of the three pool size classes are presented in Table 13. Apart from length, their profiles were very similar, a reflection of the relatively common morphology of the river across the study site. Table 13. Morphological parameters for pools among 3 pool size classes. Means are presented with standard deviations. Size Class Length (m) Flow area (m2) Top width (m) Wetted perimeter (m) Maximum depth (m) Small 1.80.2 (1.7-2.0) N=3 108.6 29.8 (83.3-141.5) N=3 61.81.4 (60.4-63.2) N=3 62.51.5 (60.9-63.8) N=3 2.30.5 (1.9-2.8) N=3 Large 8.51.4 (7.5-9.5) N=2 87.312.0 (78.8-95.7) N=2 61.01.6 (59.8-62.1) N=2 61.51.7 (60.3-62.7) N=2 1.90.1 (1.8-2.0) N=2 Very Large 25.68.6 (19.5-31.7) N=2 98.77.3 (93.5-103.8) N=2 61.50.6 (61.1-61.9) N=2 62.10.7 (61.6-62.6) N=2 2.10.1 (2.0-2.2) N=2 50% Reduction (13.3 cumecs) When 13.3 cumecs of flow occurs at Dorisvale Gauging Station, 3 breaks occur in the Daly River between Dorisvale Crossing and Cattle Creek (Table 14). This translates into one break point for every 24.56 km of river. Table 14. Location of breakpoints on the Daly River under modelled flow conditions. Upstream flow was 13.3 cumecs at Dorisvale Crossing and downstream flow was 21.2 cumecs at Cattle Creek. Breakpoints refer to sections of the river that would inhibit movement of pig-nosed turtles (<0.5 m). Landmark Distance (km) Easting Northing Pool length (km) Cp1 Dorisvale 0.00 775734 8410582 Cp3 9.16 770965 8415100 >9.46 Cp4 11.15 769734 8416517 1.80 Cp19 46.69 749665 8431792 35.50 Cp22 54.17 747717 8437410 7.50 Cp26 73.70 738867 8445392 >19.54 Under this flow condition (13.3 cumecs), the 4 break points identified above produce 3 pools in the Daly River, between Dorisvale Crossing and Cattle Creek. There was one small pool (33.3%), no intermediate pools, 1 large pool (33.3%) and 1 very large pool (33.3%). Under this flow condition only 2.4% (1.8 km) of the study reach would be fragmented into small pools.