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

10 A policy of allowing a fixed annual allocation of water to agriculture from the river and a policy of ensuring adequate environmental flows are irreconcilable. Water for agriculture should be drawn from groundwater aquifers representing accumulated recharge over several wet years, in order to assure supply and buffer the river from unacceptable reductions in flow in critical years. This will also remove difficult considerations on the timing of water extraction within years. The linkage between groundwater in the areas flagged for agriculture and river flow is not well understood. In the absence of good working models to predict the change in river flow against groundwater extraction from adjacent aquifers, an adaptive approach must be adopted. This would require accurate monitoring of the quantity of water extracted and when it is extracted, accurate monitoring of dry season flows, and accurate estimates of the flows that would be expected in the absence of water resource development. The latter estimates are possible from historical data because of precision in the recession curves once the contribution of surface flow becomes negligible. Research needs to be undertaken to determine how far from the river groundwater extraction must be in order to not have an un-buffered, immediate impact on the flows in the river. This distance will set the dimensions of the buffer zone that should be established along the river corridor. The quality of data on dry season flows obtained from the Department could be improved. There needs to be a greater commitment to maintaining river gauging stations and to quality control over the data collected. The stations need to be upgraded to more accurately measure dry-season flows. More intensive monitoring of dry season flows at multiple locations is needed if the adaptive approach is to be effective in governing water allocations. Interpretation of the Brief The aim of the overall project is to provide recommendations on environmental flows consistent with maintaining the biota of the Daly River, given competing demands of agriculture, recreation and tourism, conservation and Aboriginal culture. Our contribution to achieving this aim is built upon the following activities: model the impact of potential flow reduction, owing to water extraction for agriculture, on dry-season river connectivity in what is currently a year-round, flowing, connected system; model the impact of potential reduction in flows on dry-season water temperatures; and, provide a concrete link between altered flows and water temperatures on the life history and population dynamics of an umbrella species, the pig-nose turtle. The major environmental factors likely to influence the persistence of many biota in the Daly River, and potentially influenced by agricultural and water resource development, are Connectivity, because the Daly River currently flows in all months of the year.