Day 1 6- gabriel de los cobos - gesdec-canton of geneva

1. The Genevoisaquifer –a shared aquifer resource managementA collaboration between Switzerland and FranceDr. Gabriel de los CobosGESDEC -geologicalsurveyof the Canton of GenevaREGIONAL WORKSHOP ON GROUNDWATER RESOURCES COOPERATION IN CENTRAL ASIAUNESCO 10-11 April 2013
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SKETCH OF AQUIFERS OF THE GENEVA AREALakeGenevaGenevois aquifer2 water pumpingplants in the lake(distributing+/-80% of the drinkingwater) 11 wellscatchingground- water frommain aquifers(distributing+/-20% of the drinkingwater)

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10 wellson the Swissside5 wellson the French side

5. SoilRecentalluvial depositsUpperMoraineFluvio-Glacial depositsGroundMoraineMolasse (bedrock) aquiferformation General characteristicsof the GeneveseaquiferLengthextension: ~ 19 kmWidth: 1 to 3.5 kmThicknessof saturatedgravel: up to 50 mDarcy'spermeability: 1-2.10-3m/sArea extension: ~ 30 km2Storage coefficient: ~ 7 %
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Geologicalcross-section of the Geneveseaquifer

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Behaviourof the ‘‘Genevois’’groundwaterlevelbeforeA.R. 02468101214367369371373375377379194019451950195519601965197019751980 withdrawalsin Mm3averagegdwaterlevel(m asl) Between1940 and 1960 the groundwaterlevelwasslowlydecreasingwithoutseriouseffectsBetween1960 and 1980 the aquiferwasoverdraftedwithwithdrawalrates up to 14 Mm3/year. This overpumpingloweredthe groundwaterlevelby more than7 m in 20 years

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Urgent hydraulicmanagement: To considera decreasein withdrawalrate by usinganotherwater resource(the construction of a new water filtration and treatmentplant in the lake) To carry out a reinforcementof the naturalcapacityof groundwaterby artificialrecharge 2 criteria: 1 -water supplysecurity(diversification of water resources) 2 -economicalcriteria(the costof a groundwaterA.R. isnot the sameas a new water treatmentplant in the lake)

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Technicalaspect: Studiesand tests carriedout on the experimentalplant Administrative and politicalaspects: Severalmeetings and discussions (CH-F) in orderto 1 –Impose restrictions on use untilan A.R. plant completed2 –Establishequitablecostsharing 1972 to 1977 workon drinkingwater resourcesand hydrogeologicalissues (losses, naturalrecharge, futur pumpingand fees) in orderto layingthe bases of a futur Franco-Swissagreement.

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1977: artificialrecharge benefitsunderlined:
‹All users:availability of 15 Mm3 of drinking water stored in the underground.
‹Swiss water companies (SEA & SIG):
ability to exploiting all the existing pumping wells without the construction
of a water plant for treating lake water.
‹French communities:
Extraction of supplementary amounts of water paying their part of the costs
beyond the annual minimum allowance of 2 Mm3/year.
‹The cost of A.R. (depreciation, interest, usage and renovation costs) spread
among all groundwater users, whatever the origin of the water (natural
or artificialrecharge)

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1Water-intakestructure12Pipe to the plant (length340m)23Water treatmentplant34Pipe to the infiltration area (length700m) 455Underground infiltration area(perforatedpipes-length5000m) Description of the artificialrecharge system

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15. Impact of withdrawalrates and artificialrecharge on the groundwaterlevel-Reconstruction of groundwaterstorage-Adjustmentof the A.R. accordingto the withdrawaland the variationsin groundwaterlevel-Annualtotal pumpagebetween15 and 17 Mm3/year-Total artificialrecharge between8 and 10 Mm3/year-Good balance betweenwithdrawalsA.R. and averagegroundwaterlevel
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1978:Arrangement between the canton of Geneva & the prefecture of Haute-Savoie
¾The Arrangement ignores territorial sovereignty and territorial integrity concepts.
¾Follows a pragmatic approach based on a rational management ofthe
common resource.
¾The Arrangement covers the following matters:
-The Commission
-The annual aquifer management programme
-The groundwater recharge installation
-Water rights
-Water pricing
-Miscellaneous provisions

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The Comission : advisory committee
¾To oversee the management of the recharge of Genevese aquifer (dealing
with problems relating to the use, maintenance and monitoring of the system)
¾To asset the status of the resource in terms of pumping and A.R.
¾Responsible for reviewing the annual artificial recharge programme and the
budget prepared in line with the recharge programme, the operating costs
and the results of water quality control tests.
¾Joint commission composed of representatives from State of Geneva and
French communities and authorities and representative for water company.
¾Committee members could be accompanied by experts
¾Meetings once to twice per year, alternatively in France and in Switzerland.

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2007-2008: extension of the 1978 arrangement
¾Franco-Swiss working group of the committee created in order
to produce a basic document outlining the management of
Genevese aquifer for the next 30 years, with legal support
¾Technical specificities agreed on by the parties placed within a
global context recognised at administrative and political levels
¾Setting up the cross border legal bases for the new agreement.

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2008: The new Geneveseaquiferagreement basedon the international legalinstruments

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Agreement betweenthe State of Geneva and the French communities
¾based on the Karlsruhe agreement (art. 5 –possibility to delegate
a mission to one of the local communities)
¾in accordance with the Swiss federal constitution (cantons are free
to act autonomously and to conclude an international agreement
by themselves)
Agreement relating to the use, recharge and monitoring of Franco-Swiss Genevese aquifer signed on 18 December 2007 and entered into force on January 1, 2008 for 30 years

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Conclusions
•In 30 years of exploitation, the A.R. system of Geneva has brought over 270 Mm3of treated water into the "Geneveseaquifer".
•The choice take in the seventies between a new water treatment plant from the lake and the A.R. plant using water from the Arveriver has been perfectly judicious. It is providing the Geneva area with an optimal and safe drinking water supply thanks to the diversification and qualitative and quantitative potentialities of water resources.
•The agreement signed between Geneva and French communities is a rare example of a transboundaryagreement of an aquifer management between a Swiss canton and European Union communities.
•Some key elements which have contributed to the success of the 1978 agreement and the drafting of its successor agreement:
–Focus on the common water resource
–The handling of the administrative and policy aspects of aquifermanagement at the local level
–The ability of the canton of Geneva to handle transboundarymatters directly

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Administrative management atthe transboundarylevel
HelveticConfederationRegionDepartementArrondissement (district –area division) Communautéde Communes (district community) Canton (district) CantonCommune (local district -municipality)
EuropeanUnionFranceState

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Thankyoufor yourattention !!! Gabriel de los CobosHead of Geology/HydrogeologybranchGESDEC (Geology, Soil& Waste) DIME (Departmentof InteriorAffairs, Transport & Environment) Canton of Geneva –Switzerlandgabriel.deloscobos@etat.ge.ch