Advisory Committee Ti-Tree Water Allocation Plan Draft WAP - - PowerPoint PPT Presentation

Ti-Tree Water Advisory Committee

www.nt.gov.au

Ti-Tree Water Allocation Plan Draft WAP components presentation 25th September 2017

Ti-Tree WAP objectives

1. Avoid detrimental impacts to water dependent ecosystems as a consequence

• f consumptive water use

2. Avoid negative impacts to cultural values of places reliant upon surface or groundwater as a consequence of consumptive water use 3. Secure domestic and public water supply for current and future population 4. Provide equitable access to water available for economic activities for current and future generations (beyond 300 years) 5. Enhance opportunities for indigenous people to benefit from consumptive use and management of water

Ti-Tree WAP objectives

All available scientific research directly related to environmental and other public benefit requirements for the water resource will be applied in setting water allocations for non-consumptive use as the first priority, with allocations for consumptive use made subsequently within the remaining available water resource. Aquifers There will be no deleterious change in groundwater discharges to dependent ecosystems, and total extraction over a period of at least 100 years will not exceed 80 % of the total aquifer storage at start of extraction. In the event that current and/ or projected consumptive use exceeds the threshold levels of 80 % of the consumptive pool for aquifers, or groundwater discharges to groundwater dependent ecosystems are impacted, new groundwater Licences will not be granted unless supported by directly related scientific research into groundwater dependent ecosystem/cultural requirements.

NT Water Allocation framework

WAP Zone options

WAP “natural water balance”

Zone Water Quality (TDS (mg/L)) Groundwater Storage (GL) Groundwater Recharge (GL/YR) Central Zone <1000 1601.39 1.09 1000-1500 259.55 0.18 1500-2000 0.00 0.00 2000-4000 0.00 0.00 TOTAL 1860.94 1.26 Eastern Zone <1000 2844.57 1.93 1000-1500 391.82 0.27 1500-2000 242.05 0.16 2000-4000 19.62 0.01 TOTAL 3498.07 2.38 Northern Zone <1000 0.00 0.00 1000-1500 0.00 0.00 1500-2000 135.79 0.09 2000-4000 290.86 0.20 >4000 231.89 0.16 TOTAL 658.55 0.45 Western Zone <1000 17.43 0.01 1000-1500 1086.29 0.74 1500-2000 0.00 0.00 2000-4000 0.00 0.00 TOTAL 1103.71 0.75 Aquifer Total TOTAL 7121.26 4.84 Non-Aquifer Zone <1000 47.81 9.08 1000-1500 31.11 5.91 1500-2000 7.53 1.43 2000-4000 10.59 2.01 >4000 2.13 0.40 TOTAL 99.17 18.84 Grand Total TOTAL 7220.43 23.68

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Estimated Sustainable Yield

Definition: “The level of water extraction from a particular system which, if exceeded would compromise key environmental assets, or ecosystem functions and the productive base of the resource.”

(Source: NWI definition for ‘environmentally sustainable level of extraction’)

Estimated Sustainable Yield

Options for how ESY is represented in the Ti-Tree WAP: a) Recharge only b) Recharge + 10% depletion of storage over 300 years c) Recharge + 30% depletion of storage over 300 years d) Recharge + 50% depletion of storage over 300 years e) Recharge + 80% depletion of storage over 300 years

Option a) is theoretically available for consumptive use in perpetuity Options b) to e) are allowable for the next 300 years (2017 – 2317). At this point regional groundwater levels would be expected to draw down to their allowable limit.

Estimated Sustainable Yield

Management zone Option A Option B Option C Option D Option E Recharge Recharge + storage depletion (10%

• ver 300

years) Recharge + storage depletion (30%

• ver 300

years) Recharge + storage depletion (50%

• ver 300

years) Recharge + storage depletion (80%

• ver 300

years) Western

0.75 1.12 1.85 2.59 3.69

Central

1.26 1.88 3.13 4.37 6.23

Eastern

2.38 3.54 5.87 8.21 11.70

Northern

0.45 0.67 1.11 1.54 2.20

Aquifer Total

4.84 7.21 11.96 16.71 23.83

Non-Aquifer

18.84 18.87 18.94 19.01 19.11 Slightly conservative (could increase)

Estimated Sustainable Yield Vs Current Licensed Use

Management zone Option A Option B Option C Option D Option E 2009 WAP Allocations Current Licensed Recharge Recharge + 10% storage depletion Recharge + 30% storage depletion Recharge + 50% storage depletion Recharge + 80% storage depletion Western 0.75 1.12 1.85 2.59 3.69 3.28 2.27 Central 1.26 1.88 3.13 4.37 6.23 7.12 3.00 Eastern 2.38 3.54 5.87 8.21 11.70 3.2 2.10 Northern 0.45 0.67 1.11 1.54 2.20 0.05 0.04 Aquifer Total 4.84 7.21 11.96 16.71 23.83 13.65 7.41 Non-Aquifer 18.84 18.87 18.94 19.01 19.11

Estimated Sustainable Yield Vs Current Licensed Use

What if we combined the zones?

Management zone Option A Option B Option C Option D Option E 2009 WAP Allocations Current Licensed Recharge Recharge + 10% storage depletion Recharge + 30% storage depletion Recharge + 50% storage depletion Recharge + 80% storage depletion Western Central Eastern 4.39 6.54 10.85 15.16 21.62 13.6 7.37 Northern 0.45 0.67 1.11 1.54 2.20 0.05 0.04 Aquifer Total 4.84 7.21 11.96 16.71 23.83 13.65 7.41 Non-Aquifer 18.84 18.87 18.94 19.01 19.11

Estimated Sustainable Yield

Discussion questions

• Q. Which ESY scenario (or other scenario) is appropriate? Why?
• Q. Should the zones be changed? How?

Water licensing decisions

1. Avoid detrimental impacts to water dependent ecosystems as a consequence of consumptive water use 2. Avoid negative impacts to cultural values of places reliant upon surface or groundwater as a consequence of consumptive water use How do we safeguard cultural and environmental values (e.g. GDEs?)

• Q. What ‘rules’ should be in place to guide water licencing decisions to achieve the objectives?
• Q. What conditions should be on licences?