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

27 Predicting dry season flows Once the groundwater contribution comes to dominate flow in the Daly, as it does soon after the rains cease from the previous wet season, flow declines exponentially with time and so follows a predictable recession curve. Log flow is therefore linearly related to time, opening the possibility of predicting dry season flow at any time from a single point gauging. Rate of decline of flow depended upon the magnitude of the initial flow (taken for our calculations to be June 1) according to the relationship oFLog10004706.0001784.0 = where F0 is flow in cumecs at June 1 (Figure 12). Figure 12. Relationship between rate of decline in flow (cumecs per day) during the dry season and initial flow levels (as at June 1) for Dorisvale gauging station (G8140067) on the Daly River, Northern Territory. Flow at time t is given by tFLogFLog ot += 1010 where is defined above and t is in days from June 1. Analysis of Contemporary Flow Data Data Sources and Quality Control The Northern Territory Department of Lands Planning and Environment provided flow data for Dorisvale Gauging Station for the two years of our study. Dry-season flows for 2001 provided to us for the Dorisvale Gauging Station were inconsistent with our recession curves (Figure 13) and were not consistent with our gauging data at the same time. It subsequently transpired that the Dorisvale Gauging Station ran out of gas in May of 2001 and was not operational until December. Approaches to improving the quality of dry-season flow monitoring have been included among our recommendations.