GROUNDWATER RESOURCES

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a GWP Associate Program

NON-RENEWABLE

GROUNDWATER RESOURCES

basic concepts & management approaches DR STEPHEN FOSTER

GW-MATE Director (IAH – President)

UNESCO

UNESCO – – IHP VI IHP VI

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NON NON - - RENEWABLE GROUNDWATER RENEWABLE GROUNDWATER RESOURCES

RESOURCES

relative concept not rigid definition

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GROUNDWATER RECHARGE

GROUNDWATER RECHARGE – – RAINFALL CORRELATION RAINFALL CORRELATION

Southern Africa

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GROUNDWATER RECHARGE

sensitivity to land cover

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AQUIFER FLOW SYSTEMS

AQUIFER FLOW SYSTEMS IN SEMI IN SEMI - - ARID REGION ARID REGION

soil– soil – vegetation cover intercepting recharge vegetation cover intercepting recharge

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AQUIFER FLOW SYSTEMS

AQUIFER FLOW SYSTEMS IN ARID REGIONS IN ARID REGIONS palaeo

palaeo- - flow regime to aquatic ecosystem flow regime to aquatic ecosystem

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600 170,000

1,700,000

GREAT ARTESIAN BASIN

Australia

low 86,000

80,000

CENTRAL KALAHARI KARROO SANDSTONES

Botswana

2,500 1,280,000

1,000,000

NORTH WESTERN SAHARA

Algeria, Libya, Tunisia

1,600 6,500,000

2,200,000

NUBIAN SANDSTONES

Egypt, Libya, Sudan, Chad

CURRENT EXTRACTION

(Mm³/a) EXPLOITABLE

RESERVES (Mm³) EXTENSION

(km²) AQUIFER

SYSTEM COUNTRY

MAJOR AQUIFERS MAJOR AQUIFERS

the world’s largest storage reservoirs

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GROUNDWATER RESOURCE RENEWAL GROUNDWATER RESOURCE RENEWAL

the hydrogeological concept the hydrogeological concept

(mainly after

(mainly after Margat Margat 1984 1984 - - 92) 92)

•renewal is comparative (not absolute) concept

•relative to both aquifer storage and recharge

•subject to wide variation with geological factors and climatic parameters

year L³T/L³

Renewal Period of Aquifer S/R

% /year L³/TL³x 100

Rate of Aquifer Groundwater Renewal R/S

Mm³/year L³/T

Average Annual Aquifer Recharge Rate R

Mm³ L³

Total Drainable Aquifer Storage Reserves S

<groundwater resource renewal is the replacement or displacement of groundwater in aquifer storage through recharge>

UNITS DIMENSION

SYMBOL PARAMETER

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• extraction of groundwater from aquifer having predominantly non-renewable

resources with depletion of aquifer storage

(mainly storage reserves unlikely to be replenished over ‘human history’)

• available for extraction (over a finite period) from the storage reserve of an aquifer with low current average renewal but large storage capacity

NON NON - - RENEWABLE GROUNDWATER RESOURCES RENEWABLE GROUNDWATER RESOURCES

GROUNDWATER MINING

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• physically unsustainable development occurs in two distinctive scenarios

- planned groundwater resource mining

- unplanned or accidental aquifer overdevelopment

• constraining use on grounds of physical unsustainability is unrealistic

• ‘socially sustainable groundwater mining’ is not a contradiction in terms

GROUNDWATER RESOURCE DEVELOPMENT GROUNDWATER RESOURCE DEVELOPMENT

social versus physical sustainability

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CENTRAL KALAHARI – BOTSWANA planned mining of mainly

non-renewable groundwater – the exception not the rule

example

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JWANENG MINE –SOUTHERN BOTSWANA

hydrogeological structure and worst-case wellfield drawdown

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SANA’A BASIN – YEMEN

unplanned mining of partly non-renewable groundwater

example

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GROUNDWATER RESOURCE MANAGEMENT GROUNDWATER RESOURCE MANAGEMENT

‘rationalization scenarios for unplanned situations ‘ rationalization scenarios for unplanned situations’ ’

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NON NON - - RENEWABLE GROUNDWATER RESOURCES RENEWABLE GROUNDWATER RESOURCES philosophy of socially

philosophy of socially - - sustainable management sustainable management

• development can be socially-sustainable providing certain criteria met and specific risks managed

• flexible/adaptive risk-based approach needed in view of significant hydrogeological uncertainty

• ‘social sustainability’ requires following to be considered :

– use must lead to clear improvement in social well-being/livelihoods – acceptable balance between short-term benefits and long-term costs – social ‘exit-strategy’ when aquifer becomes seriously depleted

– how issue of inter-generational equity can be addressed

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GROUNDWATER GROUNDWATER

MANAGEMENT NEEDS the neglected resource

out of (public) sight, out of (political) mind

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GROUNDWATER RESOURCES MANAGEMENT GROUNDWATER RESOURCES MANAGEMENT

reconciling

reconciling ‘ ‘ bottom bottom - - up up ’ ’ and and ‘ ‘ top top - - down down ’ ’

Economic Instruments Strategic Planning Level

- national water use priorities - food + energy policy

- river basin context - legal framework

Local Institutional Level

- role of local government - groundwater use rights - stakeholder awareness +

participation

Demand/Supply Interventions

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BENEFITS OF IMPROVED IRRIGATION METHODS

on real water-saving and energy conservation

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GROUNDWATER RESOURCE SAVINGS GROUNDWATER RESOURCE SAVINGS

key issues for agricultural sustainability

• need to distinguish between resource saving from pumping energy use savings in improving irrigation efficiency

• improving irrigation efficiency alone mean real resource savings (and can result in the reverse)

• need to constrain irrigated area and reduce rights allocations

• crop changes can be very effective for groundwater savings:

- plasticulture/greenhouses

(also increasing water productivity)

- drought-resistent and or rainfed crop types

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GROUNDWATER RESOURCES MANAGEMENT GROUNDWATER RESOURCES MANAGEMENT

reconciling

reconciling ‘ ‘ bottom bottom - - up up ’ ’ and and ‘ ‘ top top - - down down ’ ’

participation

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STAKEHOLDER STAKEHOLDER PARTICIPATION PARTICIPATION

institutional mechanisms

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GUANAJUATO – MEXICO

evolution of population and waterwell drilling

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COTAS:

COTAS: embryonic embryonic aquifer aquifer management management organisations

organisations

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GROUNDWATER RESOURCES MANAGEMENT GROUNDWATER RESOURCES MANAGEMENT

reconciling

reconciling ‘ ‘ bottom bottom - - up up ’ ’ and and ‘ ‘ top top - - down down ’ ’

participation

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CLOSE THE GAP CLOSE THE GAP

between full economic cost & what users pay

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GROUNDWATER MANAGEMENT : GROUNDWATER MANAGEMENT :

KEY MESSAGES KEY MESSAGES

Technical Foundation Technical Foundation

• appreciation of resource uncertainty and sound diagnosis of aquifer susceptibility to irreversible side-effects

• demand management must focus on

‘consumptive use’ and ‘real water savings’

• rational to use non-renewable reserves for socio-economic development if properly

understood and planned

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NON NON - - RENEWABLE GROUNDWATER RESOURCES RENEWABLE GROUNDWATER RESOURCES

guidelines for socially

guidelines for socially - - sustainable management sustainable management

• high-level authority in political hierarchy for use policy

• government (multi-function agency or multi-sector committee) must play central role

• full/balanced participation of groundwater users essential

• time-based system of groundwater use rights needed

• careful monitoring of groundwater use and aquifer response

• systematic periodic review of aquifer performance/abstraction policy

• key supporting management tools :

– sound aquifer conceptual and numerical model

– socio-economic assessment of use options/implications

– acceptable system of measuring/estimating volumetric abstraction