Rick Evans, Kate Dowsley, Louise Lennon

1. Technical and economic feasibility of Managed Aquifer Recharge for irrigation development in Northern Australia Rick Evans, Kate Dowsley, Louise Lennon

2. N Australia is 7 times the area of Spain

4. Ref: CSIRO (2015)

5. Ref: CSIRO 2015. • Out of 25 major irrigation developments in Northern Australia, only 2 have succeeded.

6. WaterSourcePhilosophy 1 2 4 3 There is considerable variation in the timing, magnitude and intensity of the wet season across Northern Australia. Surface water bodies in Northern Australia (ie dams) lose a lot of water to evaporation. Water resource development must be scalable. Transporting water is very expensive. Project concept – capture surface water during wet season, store in the groundwater (MAR) and recover and use during the dry season

7. What is Managed Aquifer Recharge? • MAR is the purposeful recharge of water to aquifers for subsequent recovery or environmental benefit.

8. Drivers for the projects • NT project • Concept • Stray Creek and King River • Economics • Benefits, challenges • Pilbara project • Concept • Investigation sites • Example irrigation scheme • Economics • Challenges and opportunities • Strategic conclusions

9. Status of MAR in Australia (2012) • Location and type of current MAR schemes in Australia ASR – Aquifer storage and recovery ASTR – Aquifer storage, transfer and recovery

10. Burdekin Delta (Qld) ~ 45,000 ML/yr

11. Alice Springs MAR; ~ 1,000 ML/yr

12. Managed Aquifer Recharge Weir – W.A.

13. Centre Pivot based on MAR weir

14. Feasibility of MAR in Northern Australia • Key criteria for MAR: • Source water supply • Suitable aquifer: • Accessible aquifer in terms of depth to aquifer • Distance between source water and aquifer • Available storage in aquifer • Aquifer properties • Ease of extraction from aquifer • Demand • Soils suitable for irrigation

15. Water availability

16. Hydrogeological factors in MAR method selection • Weirs - Is it saturated or unsaturated flow? - 4 fold difference. • Infiltration rate • Clogging rate – ease of maintenance • Aquifer Storage potential B. Injection bores • Injection depth (Preferably < 100m) • T and S of target aquifer • Pumping head < 40m • Pre treatment costs

17. Map of location of alluvial geological units in Northern Australia

18. Potential sites for irrigation using MAR in NT

19. Opportunities for groundwater & MAR in the Pilbara • Capturing surface water flows during wet season • Enhancing infiltration using a weir • Store water in the aquifer and recover and use during the dry season

20. De Grey Station scheme

21. Strategic conclusions • MAR is economically feasible at specific sites, depending largely on the local hydrogeology & source water availability. • MAR is not cheap, but very reasonable at National scale (A$120 to A$150/ML) • NT and WA case studies are very different: MAR concepts, demand profiles, crop types, policy setting, local enthusiasm.

22. Key benefits • MAR is technically feasible in many cases; choosing the most economic method is the opportunity • Environmentally benign/minimal impact • Harvesting wet season excess flows • Economic for specific crop types • In Pilbara, must develop groundwater first, MAR is the long term augmentation for sustainability. • In NT, policy reform required to create demand. If demand, then MAR is economic.

23. KEY CONCLUSIONS • There is sufficient water in Wet Season Flow for MAR • MAR is economic for certain crops and specific situations.