SUSTAINABLE GROUNDWATER IRRIGATION

the GW.MATE vision on resource use

and management approaches

Stephen Foster World Bank GW.MATE Director 2000-10 Global Water Partnership–Senior Adviser IAH Past President 2004-08

University of London–Visiting Professor

GLOBAL WATER

PARTNERSHIP Global Water

Partnership

The Moles’ eye

view ?

SOUTH ASIA GROUNDWATER IRRIGATION BOOM

scale, drivers, benefits and issues

• massive growth of irrigation waterwells (57% total use) mainly private investment stimulated by government

• groundwater very ‘popular’ with farmers if energy-supply reliable almost regardless of energy cost – direct access, near point-of-use (well-suited to pressurised irrigation)

• large groundwater economies with major social benefits NOTABLY drought water-supply security avoiding crop yields impacts

• but unconstrained use tends to generate excessive resource demand, with sustainability and social concerns given population pressure on the land above most aquifers – initially groundwater minor component of overall agro-input costs

• resource base not generally in imminent ‘danger of collapse’ – rather more in need of some ‘loving care’

GROUNDWATER RESOURCE DEPLETION some might ask why intervene –

just let anarchy and nature run its course

phreatophytic vegetation stress

aquifer compaction

transmissivity reduction

pumping lifts/costs increase

borehole yield reduction

springflow/baseflow reduction

REVERSIBLE

INTERFERENCE

saline water intrusion

ingress of polluted water

land subsidence and related impacts

IRREVERSIBLE

DETERIORATION

factors causing social and environmental cost

GROUNDWATER RESOURCE MANAGEMENT

like playing soccer – need to vary strategy with the pitch you’re playing on

hydrogeological setting of aquifer both frames the resource problem and

constrains the management solution

help – it should have been cricket

SOUTH ASIA simplified hydrogeological provinces

HYDROGEOLOGICAL PROVINCES

•Hard-Rock Peninsular India

• Indo-Gangetic Alluvial Plains • Localised Graben-Fill Aquifers

• Localised Coastal Formations

• Himalayan Valley Aquifers

INDO-GANGETIC PLAIN

characterisation of major alluvial aquifers

• large storage (60,000 mm in upper layers) • but insidious salinisation threats widely exist • groundwater/surface water relations critical

• ‘national grain basket’ with almost entire land area cropped for rabi wheat/kharib rice – some 70% with waterwell irrigation • resultant excessive groundwater abstraction equivalent to 120-150 mm/a – water-table continuously declining at 0.5-0.8 m/a • but about 35-40% of recharge by irrigation canal seepage • salinisation down-gradient and severe depletion around all towns • since 2008 statutory deferral of paddy planting to June (by up to 35 days) estimated to have reduced by NBET by 80-100 mm/a ?

INDIAN PUNJAB Peneplain

INDO-GANGETIC PLAIN

characterisation of major alluvial aquifers

• large storage (> 60,000 mm in upper layers) • but insidious salinisation threats widely exist • groundwater/surface water relations critical

GROUNDWATER MANAGEMENT APPROACHES from Spontaneous to Planned Conjunctive Use

• integrated modelling suggests average cropping intensity could be increased from < 150% to >220% with ‘planned conjunctive use’ (with crop diversification also increasing ‘irrigation-water productivity’) – reducing ‘upstream’ canal losses/over-irrigation, improving

canal distribution and downstream’ irrigation service levels

– increasing groundwater use in ‘upstream areas’ and reducing use in ‘downstream areas’ with improved canal-water availability

• but how to overcome social/economic obstacles (power of head-canal land owners, split institutional responsibility, comparative water cost to users and initial capital investment needs) ?

Jaunpur Irrigation-Canal

Command Uttar Pradesh, India

PENINSULAR INDIA characterisation of weathered hard-rock aquifers

• useful but small storage (< 500 mm) • local sluggish flow

• recharge constraints

GROUNDWATER MANAGEMENT APPROACHES

Community-Based Self Regulation

• community ‘self-regulation’ goes further than stakeholder participation in resource management – only feasible approach for large groups of very small users and where groundwater flow system localised (still important for local government to play permanent ‘lighthouse function’ in support and for up-scaling of positive outcomes)

• shift social behaviour from ‘destructive competition for dwindling storage reserves’ (with few ‘winners’) to ‘constructive dialogue on productive use of available average recharge’

(with many beneficiaries)

• successful recharge enhancement in favourable hill-foot setting • inspired community decision on ‘dugwell only use’ for irrigation – eliminating divisive competition for limited groundwater storage and focusing farmers’ attention on ‘irrigation water productivity’ • crop-water budgeting based on antecedent conditions, ban on sugar-cane cultivation and intelligent crop diversification

• excellent outcomes on groundwater sustainability, higher-value crops/products, family incomes and eliminated water-supply tankers

MAHARASHTRA-INDIA Hivre Bazaar successful communuity self-regulation

PRAGMATIC FRAMEWORK FOR GROUNDWATER RESOURCE MANAGEMENT

IN HEAVILY-EXPLOITED AQUIFERS

• first reaction of governments often is to propose major stand-alone investments in :

• aquifer recharge enhancement and/or • ‘efficient’ irrigation technology rather than :

• focusing on ‘underlying core issue’ of reducing consumptive water-use (preferably ‘non-beneficial’) with parallel need to raise water-use productivity and to maintain/improve farmer incomes • confronting the harsh reality of weakly-recharged aquifers sometimes trying to support inappropriate agricultural economies

GROUNDWATER RESOURCE MANAGEMENT fantasy of ‘simple panacea’ or ‘quick fix’

for excessive irrigation abstraction

GROUNDWATER MANAGEMENT APPROACHES

National/State Macro-Policy Modifications

• modifications to agricultural policy can exert a powerful influence on groundwater irrigation use :

• discouraging alfalfa irrigation for arid-zone livestock farming • geographic bans on sugar-cane cultivation

• statutory deferral of rice planting date

• unravelling nexus between groundwater use and rural electricity pricing is not straight

• not I believe the primary cause of groundwater depletion • may even be a socio-political justification for some subsidy given invariably much lower cost to users of ‘canal-water • however, flat-rate tariffs (by pump rating or connection potential) are always perverse and potentially disastrous from standpoint of energy consumption and the electricity utilities • water-table recovery through groundwater management measures will reap large benefits (reduce pump head losses)

GROUNDWATER MANAGEMENT - contribution to key workshop outputs

• no ‘simple blueprint’ – management measures must be tailored to ‘hydrogeological setting’ of resource

• policy and strategy development requires understanding of both ‘use dynamics’ as well as ‘resource characteristics’

• management without user participation impossible - but by users alone (without groundwater agency support) is questionable

FOR OPERATIONAL STAFF OR ALL AGENCIES

• groundwater agencies tend to be ‘marginalised’ and/or undersized (rarely facing strategic issues or involved with integrated policy development) – promote dialogue on their key functions and

transformation opportunities (identify training needs)

• inter-sector working groups/joint work programmes/co-immersion

courses between agricultural sector and groundwater sub-sector

www.worldbank.org/gwmate

www.gwpforum.org

also UNDP-CAPNET Training Manual