Download Alex Gardner (University of Western Australia)

Groundwater as a “drought reserve”
in a drying climate
Presentation to the University of Melbourne Law School
Workshop on Water Governance for Resilience
Alex Gardner
Faculty of Law, UWA
25/09/14
Overview:
Reforms for groundwater drought reserve
1.
2.
3.
4.
5.
Orienting South West Western Australia
National water policy reforms
Planning for climate change adaptation
Entitlement holders saving water
Conclusions - groundwater based system
1. Orienting South West WA
• Surface water yield 1/4 of 1970
• Groundwater makes up around
three quarters of water use
• Total groundwater use around
850GL/yr (2009 estimate)
• Self-supply for gardens, public
open space, horticulture, mining,
industry is around 700GL/yr
• important for public water supply
(~150GL/yr and 40% of IWSS)
• New alternative sources:
• Desalination 150 GL/yr (from 2006)
• Recycled water; GWR  28 GL/yr
• Demand management
Source: CSIRO 2009
25/09/14
• environmental water allocations
frequently breached
3
Rainfall trend since 1987
- predicted vs actual
4
Public water supply strategy
SUPPLY AND DEMAND FOR THE INTEGRATED SCHEME (IWSS)
350
Groundwater Security Strategy
300
Southern Seawater Desalination Plant
Perth Seawater Desalination Plant
250
Groundwater Supply
GIGALITRES
Surface Water (including trade)
200
150
100
50
0
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
YEAR
Source: Water Corporation (2013)
2020
Groundwater resources declining
1. Gnangara Superficial
2. Gnangara Confined
3. SW Ramsar wetland:
declining water table
impacts water quality
Gnangara Groundwater System
Rainfall
Superficial aquifer well
Confined aquifer well
Bassendean Sand
River
Guildford Clay
Coastal Limestone
ial
Wetland
Indian
Ocean
Caves
Confining Bed
Superfic
aquifer
ville aquifer
Leedered
Confining B
Confining Bed
Yarragadee aquifer
25/09/14
tl
au
F
ng
arli
D
2. National Water Policy Reforms
Current Law (since 2001)
• Landholder eligibility to hold licence
• No statutory plans or consumptive pool –
non-statutory allocation limits
• 10 yr licences with tradable entitlements
• Entitlements = maximum annual volume
• Poor water accounting & enforcement
• Legal environmental water allocations
under EIA law or water licence conditions
National Water Initiative reforms
proposed but constantly delayed since 2006:
• Statutory allocation limits and plans for
consumptive pool(s)
• Tradable perpetual share entitlements
• Environmental water holder
RiWI Act turns 100, 22 Sept 2014
3. Climate change and
groundwater planning
• Currently no requirement in the RIWI Act to
consider climate change risks in groundwater
planning (cf Water Act 2007 (Cth))
• In practice, limited use of climate change
scenarios in non-statutory allocation plans
• This is changing - DoW has new GIS tool to
produce ‘future climate’ scenarios for any part
of WA, to be used in future water planning.
25/09/14
9
Law reform proposal:
duty to address climate change
The new water resource management
legislation should require the Minister to
consider climate change risks in the
preparation of statutory water allocation plans
and to address those risks in the plan
provisions: for example,
• declining allocation limits over plan life
• zoning areas for no consumptive use,
including by domestic bores
25/09/14
10
4. Groundwater as a
‘drought reserve’
• Can groundwater be sustainably used as a
drought reserve in a drying climate?
• What regulatory arrangements would best
support this?
• Case study: groundwater as a drought
reserve for the IWSS public water supply
• Regulatory options for entitlements saving
water
30/07/14
11
The Variable Groundwater
Extraction Rule (VGAR) for IWSS
25/09/14
12
Failure of the VGAR
in a drying climate
• Problem: In a declining rainfall trend the
VGAR results in sustained high
groundwater abstraction, compounding the
effects of low recharge on the groundwater
system (DoW, 2013)
• DoW solution: 5 year, 110GL/yr average
extraction for the Integrated Water Supply
Scheme.
25/09/14
13
Groundwater as a ‘drought reserve’:
- regulatory options for entitlements
• Entitlement holders have:
• carryover and borrowing rights in suitable aquifers
• compulsory ‘banking’ (eg 10% of entitlement)
accessible only on ministerial declaration
• Department reserves water and auctions short
term licences on ministerial declaration
• Independent water holder retains water
entitlements in suitable aquifers that it auctions
in extreme drought
• Managed Aquifer Recharge of recycled water
should include a restoration share
26/09/14
14
Conclusions
for a Groundwater based system
• Information challenges – especially modeling
• NWI reforms – they are not enough
• Long term water resources assessment and
climate adaptation planning
• NWI flexibility of share entitlements with
obligations to plan for climate change
- statutory duties to model, zone and save
• Urban water supply – alternative sources
• Social and cultural values