MANAGING WATER QUANTITY AT ALLOCATION LIMITS

Freshwater Management Forum 2013Professor Bryan Jenkins

Waterways Centre: University of Canterbury and Lincoln University

PRESENTATION COVERAGE

• 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 5Enabling 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 effectsMain 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-BACKFoothill 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• Rapid growth in use of

groundwater• Sustainability limit exceeded• Drop in groundwater levels

and spring-fed streams

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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 belowminimum 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

Te Ngawai Water Users’ Website

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• 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

2000 2050 2100Calendar Year

NN

N lo

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20% reductionof landuse

N load in 2005

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