Territory Stories

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

Details:

Title

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

Creator

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

Collection

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

Date

2002-11-20

Location

Daly River

Abstract

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.

Notes

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

Language

English

Subject

Environmental Flows; Modelling; Biota

Publisher name

Northern Territory Government

Place of publication

Palmerston

Edition

Final Report

Series

57/2002; National River health program

Format

75 pages ; 30 cm

File type

application/pdf

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Parent handle

https://hdl.handle.net/10070/885434

Citation address

https://hdl.handle.net/10070/885435

Page content

47 Table 16. The frequency of occurrence of minimum flows in our 14 flow increments against years at the Dorisvale gauging station (G8140067), Daly River, Northern Territory. N=40years. Class Number of Years Percent of Years Cumulative frequency Cumulative percent Q < 2.0 1 2.5 1 2.5 2.0 < Q < 2.5 4 10 5 12.5 2.5 < Q < 3.0 6 15 11 27.5 3.0 < Q < 3.5 4 10 15 37.5 3.5 < Q < 4.0 6 15 21 52.5 4.0 < Q < 4.8 7 17.5 28 70 4.8 < Q < 7.6 9 22.5 37 92.5 7.6 < Q < 10.5 1 2.5 38 95 10.5 < Q < 13.3 0 0 38 95 13.3 < Q < 16.1 0 0 38 95 16.1 < Q < 18.9 2 5 40 100 18.9 < Q < 21.2 0 0 40 100 21.2 < Q < 24.6 0 0 40 100 24.6 < Q < 27.4 0 0 40 100 Water Temperature versus Flow General Approach A model has been developed to simulate water temperatures in the Daly River between Dorisvale and Cattle Creek as they respond to changes in weather, water depth and flow. The purpose of the model is to allow estimation of the potential impact on riverine water temperatures of changes in river flow due to irrigation extraction. The model includes a series of meteorological factors that increase or decrease water temperatures. The water in the river is warmed due to the input of solar radiation and infrared emission from the sky to the water surface. It is cooled by evaporation, by conduction between the air and the water (if the water is warmer than the air) and by thermal infrared emission from the water surface to the sky. The model also includes an input of warm spring water into the river between Dorisvale and Jinduckin Creek. A measurement program was instigated to obtain the data necessary to support the model application. Measurements most suitable for model application and calibration were obtained for a 6-day period in July 2000 and for a second 12-day period in September of the same year. In this year, a meteorological station was established in the river to allow estimation of the exchange of heat between the river and the atmosphere. Also, precision water temperature measurements were made at four sites along the river (Dorisvale, Jinduckin Creek, Oolloo, Cattle Creek) to provide data needed to calibrate and test the model. In 2001, we were able to use measurements obtained during a 58-day measurement period extending from the middle of June to the middle of September. For this period, meteorological measurements were obtained at a station near the river and water temperatures were measured at Dorisvale, Jinduckin Creek, and Cattle Creek Due to the much longer data record in 2002, most of our analysis was undertaken for this year so the model development and application is described in this context in the following.


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