NON-RENEWABLE GROUNDWATER RESOURCES

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1 UNESCO IHP VI NON-RENEWABLE GROUNDWATER RESOURCES basic concepts & management approaches DR STEPHEN FOSTER GW-MATE Director (IAH President) a GWP Associate Program

2 NON-RENEWABLE GROUNDWATER RESOURCES relative concept not rigid definition

3 GROUNDWATER RECHARGE RAINFALL CORRELATION Southern Africa

4 GROUNDWATER RECHARGE sensitivity to land cover

5 AQUIFER FLOW SYSTEMS IN SEMI-ARID REGION soil vegetation cover intercepting recharge

6 AQUIFER FLOW SYSTEMS IN ARID REGIONS palaeo-flow regime to aquatic ecosystem

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8 MAJOR AQUIFERS MAJOR AQUIFERS the world s largest storage reservoirs COUNTRY AQUIFER SYSTEM EXTENSION (km 2 ) EXPLOITABLE RESERVES (Mm 3 ) CURRENT EXTRACTION (Mm 3 /a) Egypt, Libya, Sudan, Chad NUBIAN SANDSTONES 2,200,000 6,500,000 1,600 Algeria, Libya, Tunisia NORTH WESTERN SAHARA 1,000,000 1,280,000 2,500 CENTRAL KALAHARI Botswana KARROO SANDSTONES 80,000 86,000 low Australia GREAT ARTESIAN BASIN 1,700, ,

9 GROUNDWATER RESOURCE RENEWAL the hydrogeological concept (mainly after Margat ) 92) PARAMETER SYMBOL DIMENSION UNITS <groundwater resource renewal is the replacement or displacement of groundwater in aquifer storage through recharge> Total Drainable Aquifer Storage Reserves S L 3 Mm 3 Average Annual Aquifer Recharge Rate R L 3 /T Mm 3 /year Rate of Aquifer Groundwater Renewal R/S L 3 /TL 3 x 100 % /year Renewal Period of Aquifer S/R L 3 T/L 3 year renewal is comparative (not absolute) concept relative to both aquifer storage and recharge subject to wide variation with geological factors and climatic parameters

10 NON-RENEWABLE GROUNDWATER RESOURCES available for extraction (over a finite period) from the storage reserve of an aquifer with low current average renewal but large storage capacity GROUNDWATER MINING 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 )

11 GROUNDWATER RESOURCE DEVELOPMENT social versus physical sustainability 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

12 CENTRAL KALAHARI BOTSWANA planned mining of mainly non-renewable groundwater the exception not the rule example

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14 JWANENG MINE SOUTHERN BOTSWANA hydrogeological structure and worst-case wellfield drawdown

15 SANA A BASIN YEMEN unplanned mining of partly non-renewable groundwater example

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18 GROUNDWATER RESOURCE MANAGEMENT rationalization scenarios for unplanned situations

19 NON-RENEWABLE GROUNDWATER RESOURCES philosophy of socially-sustainable 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

20 GROUNDWATER MANAGEMENT NEEDS the neglected resource out of (public) sight, out of (political) mind

21 GROUNDWATER RESOURCES MANAGEMENT reconciling bottom-up and top-down Strategic Planning Level Demand/Supply Interventions - 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 Economic Instruments

22 BENEFITS OF IMPROVED IRRIGATION METHODS on real water-saving and energy conservation

23 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

24 GROUNDWATER RESOURCES MANAGEMENT reconciling bottom-up and top-down Strategic Planning Level Demand/Supply Interventions - 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 Economic Instruments

25 STAKEHOLDER PARTICIPATION institutional mechanisms

26 GUANAJUATO MEXICO evolution of population and waterwell drilling

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28 COTAS: embryonic aquifer management organisations

29 GROUNDWATER RESOURCES MANAGEMENT reconciling bottom-up and top-down Strategic Planning Level Demand/Supply Interventions - 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 Economic Instruments

30 CLOSE THE GAP CLOSE THE GAP between full economic cost & what users pay

31 GROUNDWATER MANAGEMENT : KEY MESSAGES 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

32 NON-RENEWABLE GROUNDWATER RESOURCES guidelines for socially-sustainable 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