MANAGING WATER QUANTITY AT ALLOCATION LIMITS
Freshwater Management Forum 2013
Professor Bryan Jenkins
Waterways Centre: University of Canterbury and Lincoln University
PRESENTATION COVERAGE
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Major Issues around Over-Allocation
Examples of Claw-back Strategies
Adaptive Management Approaches
Mitigating Effects on Existing Users
Exchange Mechanisms and Incentives
WATER ALLOCATION BASED ON RMA sec 5
Enabling resource use for social, economic and cultural
well being, while
• sustaining resource for use of future generations
• safeguarding life supporting capacity
• avoiding, remedying or mitigating adverse effects
Main over-allocation concerns
• replenishment of aquifers
• ecological flows in rivers
• water quality effects of water use
• reliability of supply for existing users
PAREORA: EXAMPLE OF CLAW-BACK
Foothill River South Canterbury
- irrigation
- town supply
- industry
ALLOCATION LIMITS SET BY CATCHMENT BOARD
• Total consented allocation
- 940 l/s (142% of 7D MALF c.f. interim limit 30%)
• Minimum flow
- 300 l/s (45% of 7D MALF c.f. interim limit 90%)
Notes:
Mean Annual Low Flow (7 day): lowest flow over 7 consecutive
days in a year; average of annual values over data record
(660 l/s for Pareora River)
Interim Limits: from Proposed NES for ecological flows
OUTCOME OF COLLABORATIVE AND RMA PROCESSES
• “A Block” Allocation
- 198 l/s (30% MALF)
• Minimum flows next 5 years (Dec-Sep)
- 50% restriction at 400 l/s
- total cessation at 300 l/s
• Minimum flows after 5 years (Dec-Sep)
- 50% restriction at 470 l/s
- total cessation at 400 l/s
• Minimum flow for A Block holders to take to storage
- 1600 l/s
• Establish B Block allocation
- 2500 l/s at minimum flow of 5000 l/s
BALANCING WATER PROTECTION AND
ECONOMIC DEVELOPMENT
• Involve those affected in a collaborative process
• Give the outcome of that process statutory backing
• Allow time for transition to increased water
protection
• Provide water at higher river flows for storage to
offset loss on run-of-river allocation
• Existing users get access to higher flows ahead of
new applicants
RAKAIA SELWYN LIMITS
250
First order limit 208 Mm³
200
150
100
50
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
0
1990
Groundwater allocation (million cubic metres per year)
• Rapid growth in use of
groundwater
• Sustainability limit exceeded
• Drop in groundwater levels
and spring-fed streams
ADDING CONTROLS FOR CUMULATIVE
EFFECTS TO INTERFERENCE CONTROLS
Restorative Programme for Lowland Streams
• Annual limits on consents in fully allocated zones
• Metering of groundwater wells
• Restrictions on wells with hydraulic connection to
lowland streams
• Ability to vary limits based on water in
groundwater system
GROUNDWATER ALLOCATION AND ADAPTIVE
MANAGEMENT
• Current groundwater allocation
- annual consented volume based on volume needed
in a dry year (1 in 5 year drought): not needed 4
years out of 5
- instantaneous volume (rate of pumping) limited by
interference effects on neighbouring bores
- zone allocation limits based on average use and past
irrigation practices to protect groundwater levels
and flows in groundwater-fed streams
ANTECEDENT RECHARGE PROPOSAL
• At full allocation in a period of low recharge it is not
possible to:
- provide consented volumes, and
- maintain flows in groundwater-fed streams
• Adaptive alternative: relate allocation to antecedent
recharge:
- base entitlement as fixed percentage of consented
annual allocation
- adaptive entitlement as variable amount based on
recent recharge history
SIMULATION OF ANTECEDENT RECHARGE
ALLOCATION 1960-2009
Source: Williams et al 2008
TE NGAWAI RIVER
• Foothill river in
South Canterbury
• Natural flow falls below
minimum flow
• River goes on restriction
• Incentive for individual users to get as much as
possible as soon as possible
COLLABORATIVE
GOVERNANCE TRIAL
• Water User Group of
irrigators established
• Real time measurement of
irrigation takes and river flow
• Results telemetered to internet site so farmers knew total
take, their take and river flow
• Voluntary adjustments by irrigators to maintain flow
above restriction levels for as long as possible
MITIGATION OF EFFECTS ON EXISTING USERS
• Creation of priority bands for existing users to help
retain reliability of supply
• Provision of storage to complement run-of-river or
groundwater supply
• Increased water use efficiency so that less water is
needed for same level of production
• Establishment of exchange mechanisms to facilitate
water transfers
WAIMAKARIRI RIVER ALLOCATION
• “A” Block allocation of 22 cumecs with minimum flow
of 46 cumecs
• Application from Central Plains Water for 25 cumecs
• If Central Plains given same status as existing users
then significant reduction in reliability
• New flow allocation
- AA 5 cumecs community and stock water
- A 17 cumecs: minimum flow 46 cumecs
- B 27 cumecs: minimum flow 68 cumecs (1:1 sharing)
INCREASE WATER AVAILABILITY THROUGH STORAGE
• Much of surface water irrigation supply is run-of-river
• When peak demand exceeds available river flow then irrigation
restricted
• Annual water availability sufficient to meet annual demand but
requires storage
• Concerns about sustainability of storage schemes in relation to
river systems
• Consideration of:
- diversion to tributary storage (Waitohi)
- off-river storage (Rangitata South)
- aquifer recharge (Central Plains)
- on-farm storage (Canterbury Plains)
INCREASED WATER USE EFFICIENCY
• More efficient irrigation methods
- match irrigation application to times of and degree of soil
moisture deficit
• Lower irrigation application rates
- reduce leakage from macropore flow
• Improve reliability of supply
- ‘just in time’ rather than ‘just in case’
• Use piped distribution rather than open channels
- water savings, reduced on-farm pumping
• Redistribution of irrigation source
- enhance recharge by using surface water in upper catchment
and groundwater in lower catchment
EXCHANGE MECHANISMS
• Collaborative agreements
- Te Ngawai water user group
• Transfers under RMA
- problem of consenting
• Cap and trade
- Murray Darling basin; Lake Taupo nitrates
• Brokerage
- concept in CWMS
WATER MARKETS IN MURRAY DARLING BASIN
• Cap on diversions in 1994: property rights in water
created
• Increase in value of entitlements and increase in
irrigator wealth
• In the “long dry”
- allocations insufficient to keep all valuable
permanent plantings in production but
enabled non-producers to sell allocation
- increased downstream salinity such that
irrigators could not use water but able to sell
allocation
Source: Young, 2011
RESULT OF DIVERSION CAP AND TRADING
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Increased water use efficiency reduced return flows
Increased capture of overland flows
Sale of end-of-season storage
Over allocation problems worsened
River Murray stopped flowing in 2002
Cap should have been on nett use rather than
diversion
• Need incentives to carry forward unused stored
water
• 1500 GL of cap equivalent needed to restore health
COMMONWEALTH INTERVENTIONS
• 500 GL secured for environment (2004-9)
• Additional commitment for $3.1 b purchase
of water entitlements
• Investment in irrigation efficiency $5.8 b
• Taxpayer cost ($8.9 b) for 15,120 irrigators
($588,000 per irrigator)
• Subsidised investment worked to
disadvantage to those farmers who had
paid for their improvements
LAKE TAUPO APPROACH
• Target: reduce nitrogen load by 20% to bring lake
back to 1990 levels
• Farms occupy 18% of land but contribute more
than 90% of the manageable nitrogen
• Market for nitrogen: farmers and Lake Taupo
Protection Trust
• Farmer can either reduce nitrogen load or
purchase nitrogen discharge allowance
• Trust has $81.5m fund and will stand in the market
to purchase nitrogen discharge allowances
and/or farmland
Predicted N load for Lake
Taupo from all northern and
western streams and seeps
Map of modelled Mean Transit
Time of the water from land to
lake in western lake catchment
Lake
Taupo
M.A. Gusyev, M. Toews, U. Morgenstern, M. Stewart and J. Hadfield (submitted).
Calibration of a transient tritium transport model to tritium time series data
from rivers and streams in the western Lake Taupo catchment, New Zealand.
Hydrol. Earth Syst. Sci, (submitted) MS No.: hess-2012-318
CONCEPT OF BROKERAGE
• Providing incentives for existing users to improve
water use efficiency and land use practices affecting
water quality
- linking efficiency requirements to access to reliable
water from storage
- inefficient or unproductive water to be bought out
and water re-allocated for environmental or
productive purposes
- third party investment in efficiency gains in exchange
for water savings
MANAGING AT AVAILABILITY LIMITS
• Issues: aquifer replenishment, ecological flows, water
quality effects, supply reliability
• Approaches: involvement, statutory backing, time to
adjust, alternative access
• Adaptive Management: incorporate natural variability,
integrated measurement
• Existing Users: priority bands, storage, improved
efficiency, exchange mechanisms
• Exchange mechanisms: collaborative governance,
transfers, cap and trade (?), brokerage