Commissioned by:

Groundwater–ResourcesandManagement

Groundwater and Climate Change:

Challenges and Possibilities

D E N M A R K

This publication was produced by the sectoral project 'Policy Advice Groundwater – Resources and Management' which is implemented by BGR on behalf of the German Federal Ministry for Economic Cooperation and Development (BMZ), and in cooperation with the Geological Survey of Denmark and Greenland (GEUS), Denmark

Editors: Friedrich Hetzel, Vanessa Vaessen, Thomas Himmelsbach, Wilhelm Struckmeier (BGR), Karen G. Villholth (GEUS)

Images: BGR, GEUS, Friedrich HetzelLayout: Uwe Benitz,

© BGR, 2008

Snježana Žariæ

Introduction

This paper gives information concerning the impacts of climate change on waterresources, and particularly groundwater. It provides an overview of the current insightsand knowledge on possible impacts and associated technical and managementchallenges due to climate change. Furthermore, it gives an overview of best options fordeveloping and safeguarding groundwater resources and the human benefits derivedfrom them.

Ist objective is to support decision makers in setting priorities for technical as well asinstitutional interventions to mitigate and adapt to climate change. Partners may begovernmental development agencies, non-governmental organisations, partner countriesand international partners in development cooperation, and other third parties.

This paper highlights the know-how and activities of the Federal Institute for Geosciencesand Natural Resources (BGR), Germany and the Geological Survey of Denmark andGreenland (GEUS), Denmark concerning the impact of climate change on groundwaterdevelopment, protection and management.

Bearing the complexity of the linkage between climate change and groundwater in mind, itis necessary to adapt groundwater management accordingly and to consider theparticular resilience of most larger aquifers as a buffer for climate change.

Groundwater and Climate Change:Challenges and Possibilities

1

Groundwater resources and their long-term replenishment are controlled by long-term

climate conditions. Climate change will therefore have a great impact on groundwater

resources.

Groundwater has to be used and managed in a sustainable way in order to maintain its

buffer and contingency supply capabilities as well as adequate water quality for human

consumption, also under predicted climate changes.

Land use planning has to consider groundwater resources as a precious and finite

resource, and take all possible measures to protect groundwater resources and their

recharge mechanisms in the long run.

“It is the poor countries which will suffer most from climate change even though they are least responsible for global warming.”

“It is also becoming increasingly clear, in North and South alike, that there is an inextricable mutual relationship between environmental sustainability and economic development ”

1Ban Ki-Moon, Secretary- of the United NationsGeneral1During the UNEP Governing Kenya, February 6, 2007.

Council/Global Ministerial Environment Forum in Nairobi,

The highly industrialised countries are themost responsible for the emission of greenhouse gases, that is made responsible forclimate change. Therefore it is nowessential that they react to climate changein order to cope with its impacts. It isfundamental to find ways of mitigatingclimate change and to look for possibilitiesof adaptation.

For developing countries, climate changeswill be more severe, hitting already themost vulnerable populations of the world.While at the same time the need fordevelopment and resilience is greater inthese countries, the capacity to encounterand anticipate the effects are generallyinadequate.

Higher temperatures increase evaporationand therefore reduce water availability for humans and ecosystems. Climate change

more costly in many regions of the worldand reinforce already existing watershortages and economic inequalities.

Globally, locations most at risk offreshwater supply problems due toclimate change are small islands, arid andsemi-arid developing countries, regionswhose freshwater is supplied by rivers fedby glacial melt or seasonal snowmelt, andcountries with a high proportion of coastallowlands and coastal megacities,particularly in the Asia-Pacific region.

Therefore, even if there are still uncer-tainties of the immediate and long-termclimate changes, measures, tools andstrategies have to be developed in orderto mitigate the impact and adapt to thechanges that are taking place.

It is time to act.

2

Climate change is a global challenge to human development

Groundwater is a key resource for human development

On a global scale, one third of the po-pulation depends on groundwater for theirdrinking water, in urban as well as ruralareas.

Groundwater also plays a pivotal role inagriculture, and an increasing portion ofgroundwater extracted is used for irrigatedagriculture. It is estimated that at least40% of the world's food is produced bygroundwater-irrigated farming, both inlow-income as well as high-incomecountries.

In arid and semi-arid areas, the de-pendency on groundwater for watersupply is between 60 and 100%.Therefore, the aim of halving the numberof people without sustainable access tosafe drinking water and basic sanitation(Millennium Development Goal, MDG 7)depends very much on how groundwaterresources are developed and managed.

However, the importance of groundwaterhas been marginalised and oftenneglected in many development strate-gies and projects. In general, support for groundwater management has not yetreceived much attention from donors.Only few activities in groundwatermanagement have been supported, andthis only marginally. For instance, inAfrica, there are at least 38 transboun-dary aquifer systems. Groundwatermanagement is supported in six basinswith very limited financial commitments.Little donor support has been contributedto this resource and remained stagnantover the last decades (GTZ, 2007).

3

ice

24 million km3

Water on earth (1.4 billion km³)

ice

24 million km3

Water on earth (1.4 billion km³)

Ageneral change in the approach to waterand groundwater management is re-quired including groundwater withinIntegrated Water Managment Resources(IWRM) concepts. In many cases,groundwater provides a secure, sufficient,and cost-effective water supply, oftenmore reliable than traditional surfacewater-based supplies.

However, groundwater, as with surfacewater, is increasingly stressed due tohuman development, population growth,increased reliance on groundwater, andclimate change. Also, once groundwaterresources are contaminated, it is verydifficult and costly to clean them.

afford it will have access,which means the gap between rich andpoor will widen extensively.

Thisreinforces a development in which wateris treated as a luxury item, where onlythose who can

Groundwater is likely to play an even greater role forhuman development underchanging climatic conditions.

“Despite the critical importance of ground-water resources in many parts of the world,there have been very few direct studies of theeffect(s) of global warming on groundwaterrecharge.” (IPCC 1996, p. 336)

“Although the effects ... on groundwaterresources are not adequately understood atpresent, they cannot be ignored.” (IPCC 1998, p.122)

“Groundwater is the major source of water across much of the world, particularly in rural areas in arid and semi-arid regions, but there has been very little research on the potential effects of climate change.” (IPCC 2001, p. 199)

4

A new understanding of what climatechange means and what impacts it hason this very special resource, upon whichwe all depend, should be promoted as abasis for better management.

It is evident that the efficient andsustainable use of groundwater calls foran integrated approach. Although theconcept of IWRM must include ground-water, unfortunately this is not consideredin practice.

Questions on water availability, access towater, and cooperation between statessharing transboundary aquifer systemsare essential. Good governance, basedon an informed knowledge aboutgroundwater resources and of climatechange impacts, should be promotedhand in hand with cooperation andparticipatory processes.

“There is a need to improve understanding and modelling of climate changes related to the hydrological cycle at scales relevant to decision making. Information about the water-related impacts of climate change is inadequate - especially with respect to water quality, aquatic ecosystems and groundwater - including their socio-economic dimensions.” (IPCC 2008, p. 4)

5

How will groundwater be affected by climate change?

We predict the climate to be lesspredictable, which is a paradox, but yetsomething we have to relate to and baseour planning on.

Despite the lack of detailed knowledge,there is consensus on qualitative changesof climate. Higher variability in precipita-tion is very likely to occur along with morefrequent extreme events, like storms,floods and droughts.

Groundwater will be less directly and moreslowly impacted by climate change, ascompared to e.g. rivers. This is becauserivers get replenished on a shorter timescale, and drought and floods are quicklyreflected in river water levels. Ground-water, on the other hand, will be affectedmuch slower. Only after prolongeddroughts groundwater levels will showdeclining trends.

This is also why increased groundwaterpumping can -for a limited time span-serve as contingency supply scenario inorder to mitigate water shortages duringdroughts when water courses have rundry.Groundwater levels of many aquifersaround the world show a decreasing trend,but this is generally due to groundwaterpumping exceeding groundwaterrecharge rate, and not to a climate-relateddecrease in groundwater recharge.

Neglecting the importance of groundwater in the process of IWRM and climate change adaptation can result in the mismanagement of surface water with severe effects on the population and the environment.

Groundwater is the intricate, but oftenoverlooked, link between surface watersand many freshwater and terrestrialecosystems. As many groundwatersystems both discharge into and arerecharged from surface water, impacts onsurface water flow regimes are expectedto affect groundwater. Thus neglecting theconsideration of groundwater in theprocess of IWRM can result in themismanagement of surface water withsevere effects on the population and theenvironment.

Increased variability in rainfall maydecrease groundwater recharge in humidareas because more frequent heavy rainwill result in the infiltration capacity of the soil being exceeded, thereby inceasingsurface runoff. In semi-arid and aridareas, however, increased rainfallvariability may increase groundwaterrecharge, because only high-intensityrainfalls are able to infiltrate fast enoughbefore evaporating, and alluvial aquifersare recharged mainly by inundationsduring floods.

6

An excessive or unwise exploitation ofgroundwater in combination with climatechange makes a lethal cocktail.

In many places, groundwater wells arealready contaminated, unprotected orclose to becoming dysfunctional due to alowering of the groundwater table close toor below the bottom of the well or due tolow and poor maintenance. Those wells,which serve as the basic water supply tomillions of livelihoods, will not be able tosupply water in times of disasters andemergencies. They will either be conta-minated by floods or dry up due todroughts.Projected sea-level rise and excessivegroundwater extraction in coastal areasand on small islands combine to increasethe risk of salinity problems in watersupplies.

The volume and the quality of ground-water depends always directly onrecharge conditions. The latter is not onlycontrolled by the amount of annualprecipitation, but is also governed by landsurface characteristics, vegetation cover,and soil properties.

All these arguments call for a better andcontinuous monitoring of the resource,both to detect water quantity as well asquality changes and to enable proper and

timely interventions.

Global warming as part of climate changewill affect groundwater indirectly. Vastareas of permafrost at high latitudes willthaw releasing huge quantities ofmethane gas and acidic pore water.Glaciers and snow caps on mountains,previously giving rise to runoff duringprolonged seasonal periods, maydisappear and rivers will be fed more byintermittent rains. Groundwater resourceswill be less recharged from such rivers andmay in fact loose rather than give waterfrom such streams.

Higher temperatures will mean higherevaporation and plant transpiration ratesand hence, more drying up of soils. Thiswill entail higher losses of soil moistureand groundwater recharge and greaterexposure to desertification and soilerosion in already hot and arid areas;these are all negative impacts for theintegrity of groundwater storage systems. On the other hand there may be more rainin certain semi-arid regions, e.g. the Sahelzone. However, it will be a challenge tocapture this rain for the benefit ofgroundwater recharge.

7

Strategies to use and develop groundwater resources under climate change

Safeguarding and enhancing the benefitsfrom groundwater under climate changewill only be possible through dedicatedefforts and intelligent development andmanagement strategies.

Within the aim of poverty eradication(Millennium Development Goal, MDG 1),the focus should lie especially in thedelivery of water supply for the poorest.

Measures of a nand mitigation

daptatio

Both, the mitigation and adaption toclimate change are essential. They areboth interconnected and not mutuallyexclusive.

The driving force for global warming is theemission of greenhouse gases. Thus,more efforts in mitigating climate changeshould be undertaken to reduceemissions and to develop new tech-nologies.A lot of energy is used for groundwaterextraction. In this context, large potentiallies in the promotion of renewableenergie, like solar energy which can beused for both groundwater extraction andfor the distillation of water of inferiorquality.Also, the large and long-term storagecapacities of natural groundwatersystems offer a wide range of adaptation measures.

Thus, climate change results infurther straining already stressed waterresources, eco-systems, and derivedsystems, which used to service us.

Besides an increased frequency anddegree of extremes, and foreseeabletrends like sea level rise, other yetunforeseeable but significant changesand trends can be expected.

Overall, climate change has already andwill increasingly have an impact ongroundwater quantity and quality.Adaptation is substantial for a sustainableuse of the precious groundwater resource.

mainly

8

Protection of groundwater

Groundwater needs to be protected, and its use and maintanance adapted toclimate change. Preventing groundwaterdegradation and unwise exploitation willprove more cost-effective than trying toclean up and restore mismanagedaquifers.

Monitoring and research have to be doneto achieve a better understanding ofgroundwater systems and theirdynamics.

Wise land use, the protection andmaintenance of groundwater systemsand technical installations for the simpleaccess to groundwater resources are keyto prevent groundwater contamination,ensure sustainability of economic invest-ments, and groundwater availabilityduring extreme (flood or drought)conditions.

BGR supports partner countries indelineating and implementinggroundwater protection zones

Securing soil infiltration

Land use and human activities greatlyinfluence groundwater conditions.Changing land use from e.g. forests toagricultural crops may have significantimpacts on groundwater levels. Becausethese effects are long-term and not directlyobvious, they are often disregarded or onlyperceived and recognised once discerned.

Most urbanisation processes come alongwith vast soil sealing together with sewersand storm water drainage systems whichare associated with very rapid peakdischarge of very often bad chemical waterquality. Both, the reduced groundwaterrecharge and the bad quality of thedischarged water, represent a threat tounderlying groundwater bodies. There-fore, measures to reduce these effects,e.g. through dedicated polder areas, greenareas and parks, where flood water can beattenuated and infilitrated, could beconsidered as integral solutions to makecities also more green and pleasant.

In rural areas, soil management, soilmoisture retention measures, andcontinuous vegetation help support soilinfiltration and groundwater rechargebesides reducing erosion risk.

Especially in hilly areas, forests should beprotected. Forestation in these areasrepresents always the best measure toimprove the physical soil properties and toincrease infiltration.

Furthermore, forests in catchment areasimprove the dynamics of discharge bysubduing fast peak discharge eventsreducing the menace of flooding for thepopulation living downstream. Erosion inhilly regions can be avoided by terracingfarmland and earth mounds along thecontour lines. Wherever possible,monocultures should be converted intoecologically sound arable land.

A very important alternative or supple-ment to the preservation or restoration ofnatural infiltration conditions is artificialgroundwater recharge. Artificial ground-water recharge is also described as a kindof (ground)water banking. Protected fromevaporation and contamination rechar-ged water can be used for differentpurposes but first of all for drinking water supply.

Generally, the costs of artificial ground-water recharge are less than investmentsnecessary for large traditional dams.

9

Managed Aquifers Recharge schemes (MAR):Many different technologies and principles exist for the managed recharge of ground-water, from the local scale capture of surface water runoff into derelict wells to restore groundwater levels, to large scale engineered infiltration galleries with recycled wastewater. All serve the same purpose of increasing the availability of groundwater and securing access in times or seasons of water shortages.

Water can be stocked in the upper aquiferlayers and thus the energy needed topump it up again is limited. Depending onthe amount needed, cheap solar energypumps or wind pumps can be used.

In poor arid rural areas, the localpopulation can build small earth dams forsurface water retention and infiltration.Surface water will be treated whilepercolating through the soil horizons; anatural effect which is for free. Howeverclogging may occur and therefore theinfiltration basin has to be cleaned duringthe dry season. The substrate can beused as a valuable fertilizer when free ofcontaminated substances.

Water saving

Advocated strategies of water saving andthe use of recycled, treated waterbecomes even more relevant in times ofclimate change.

Instead of relying on precious and finitegroundwater for all kinds of water supply,groundwater usage for irrigation purposesshould be reduced and substituted withtreated municipal wastewater for irrigationin peri-urban areas. By using good qualitygroundwater preferably for drinking water,the resource is used in a more sustainableway.

Virtual water stored in agriculturalproducts makes up part of our “waterfootprint”. Whatever we eat, a certainamount of water was used to make ourfood grow. Efficient water use must be themain objective in agriculture and thecultivation of drought resistant plantscould be an option.

Ecosystems must be protected becausethey serve as water catchment areas andnatural infiltration basins. Gallery forestsplay an important role for the river floraand fauna. Furthermore, erosion is verylimited when gallery forest are welldeveloped and dense.

These “no regret” measures are stepsthat can be taken anytime, both to combatclimate change and to reduce generalstress on water resources.

10

The amount of water needed for agri-cultural use is still incredibly high andtoday is estimated to be 70% of all humanwater extraction. Therefore, soundirrigation systems could contribute toavoid the waste of this precious resource.Open canals should be replaced byclosed pipes in order to protect againstevaporation. To reduce evaporation thesoil should be covered completely withplants, and therefore a multilayer storey issuggested.

Strategies for policy-making

Many principles applicable for thesustainable management of surface wateris equally valid for groundwater manage-ment.Thus, capacity development, goodgovernance and transparency are key-stones which have to be considered.Often, the insufficiency of supplyingdrinking water and sanitation is driven byan inefficient supply of services ratherthan by water shortages. Mismanage-ment, corruption, lack of appropriateinstitutions and a shortage of newinvestments in building human capacityand physical infrastructure contribute tothis development (Water GovernanceFacility, 2008).

For decision makers the available dataand information concerning the waterbalance and changes due to climatechange have to be comprehensive andeasily accessible. Still, not only knowledgeshould increase and data collected, but itis absolutely important that the data iscomprehensive and easily accessible.

Due to increasing investments in theglobal 'water market', governmentsshould support strong regulatory systemswhich are based on monitoring, datacollection and sharing of knowledge bynational water authorities.

In rural areas of semi arid or arid regions,conflicts concerning the access togroundwater are not unusual. Often it isthe extraction of groundwater resourcesof different conflicting parties heavilydependent on already stressed ground-water resources which spark off violentconflicts.

One state's solution becomes anotherstate's problem. This calls for acooperative and a regulatory approachbeyond the principle of 'first come firstserve'.

For the transboundary management ofgroundwater resources, the exchange of data and relevant information has to beinstitutionalised. Thus, a harmonisationof national laws across borders is critical.

11

Every new settlement should take ground-

water resources into account and the pro-

tection of the aquifer should have high priority.

Overall, good water governance and thepolitical will to implement commonagreements are the fundamentalcornerstones for adaptation and mitigationmeasures.

The use of non-renewable (fossil) ground-water resources has to be avoided as faras possible. However, in humanitarianemergency situations, the use of non-renewable water resources can be theonly option in order to save lives ifavailable renewable water resources arequantitatively and qualitatively notsufficient.

For long-lasting humanitarian interven-tions, alternative options are to beintroduced to slow down the excessive useof fossil groundwater (e.g. desalination,reuse, purification). Where non-renewablegroundwater resources are already anelementary component of water use,every opportu-nity must be utilised toimprove the water balance. In particular,the use of fossil water must always besubject to a comprehensive evaluation ofalternative options (BMZ 2006).

Technical know-how is fundamental inassuring that land use planning takesgroundwater conditions into account. Inorder to be prepared, financing facilitieshave to be made available to constructdams for infiltration basins, infiltrationwells, and for the renaturation of riverbedsand wetlands.Open areas have to be made available inorder to catch water in polder andinundation plains. Promoting public parksand reducing soil sealing to a minimumnecessary could be an option to increaseinfiltration.

Rainwater harvesting should be in-creased by catching runoff in basins or byinfiltration wells in the underground.Every new settlement should take ground-water resources into account and theprotection of the aquifer should have highpriority.Dump sites and solid waste handling alsohave to do with groundwater. This alsoapplies to fertilizer and pesticide use inagriculture. Measures nedd to bedeveloped in order to prevent theexcessive leaching of contaminants intogroundwater resources.

12

protection zones

catchment area

well

How much does it cost?

Water is a precious and a finite resource.So why not paying for it? Water pricesshould be affordable for all. However,different tariff-systems should assure that the poor also have access to clean andaffordable water. Water prices should besubsidised for the poorest. Water supply inemergencies must be free for all. Industrialwater use has to be regulated.

Over-exploitation should be discouraged.Water savings result in a reduction ofwater prices. Part of the income fromregular water payments should be usedfor groundwater protection and adaptationmeasures.

Expertise of BGR & GEUS

BGR and GEUS as state geologicalsurveys with substantial experience ingroundwater management are keyplayers in advising and supportingdevelopment cooperation and partnercountries when it comes to the explo-ration, development, use, protection andmanagement of geological and ground-water resources.

Both have extensive know-how and long-lasting experience from a wealth ofprogrammes and projects around theworld. Their services range from activitiessuch as groundwater resources monito-ring, resource evaluation, groundwaterprotection and vulnerability assessment,pollution rehabilitation, and the develop-ment and application of modelling tools.

Feasibility studies of dams, artificialgroundwater recharge, rainwater har-vesting, and capacity building at variouslevels contribute to an effective coopera-tion. Therefore, BGR and GEUS are idealpartners for supporting geo-services inpartner countries through internationalcooperation.

13

References and further reading:

www.bgr.bund.de

www.bmz.de

http://www.grida.no/climate/ipcc_tar/wg2/pdf/wg2TARchap4.pdf

http://www.watergovernance.org/index.html

Appleton, 2003. Climate Changes the Water Rules. Dialogue on Water and Climate.Printfine Ltd., Liverpool, UK.

BGR, 2007, Strategies for the Sustainable Management of Non-renewable GroundwaterResourcesAvailable at:

BMZ 2006, Sektorkonzept Wasser.Available at:

Burns, W.C.G. 2002. The potential impacts of climate change on the freshwater resourcesof Pacific Island developing countries. In: Gleick, P.H. (Ed.). The World's Water 2000-2001: The biennial report on freshwater resources. Washingtom, DC. Island Press, pp.113-131.

GTZ.2007: Donor activity in transboundary water cooperation in Africa; Results of a G8-initiated survey 2004-2007, Deutsche Gesellschaft für Technische Zusammenarbeit(GTZ) GmbH, Eschborn 2007.

IPCC. 1996. Climate Change 1995, Impacts, adaptations and mitigation of climatechange: Scientific-technical analyses, London, Cambridge Uni. Press.

IPCC. 1998. The Regional Impacts of Climate Change: An Assessment of Vulnerability,London, Cambridge Univ. Press.

IPCC. 2001. Climate Change 2001, Impacts,Adaptation and Vulnerability.Available at:

IPCC. 2008. Climate Change and Water. IPCC Technical Paper VI.Available at: http://www.ipcc.ch/pdf/technical-papers/climate-change-water-en.pdf

Moench, M. & S. Stapleton, 2007. Water, Climate, Risk and Adaptation. Working Paper2007-01. Institute for Social and Environmental Transition (ISET). ISBN: 978-90-78988-01-4. 80 pp.

UNDP Water Governance Facility, 2008Available at:

Transparency International, 2008. Global Corruption Report 2008: Corruption in theWater Sector. edited by Dieter Zinnbauer and Rebecca Dobson. Cambridge UniversityPress, UK

UNESCO, 2006, Jean Margat « Les eaux souterraines – une richesse mondiale »

in

14

15

Notes:

Contact:

Friedrich HetzelVanessa Vaessen

Bundesanstalt für Geowissenschaften und Rohstoffe(BGR)

Stilleweg 230655 Hannover, Germany

E-mail:

Phone:web:

Friedrich.Hetzel@bgr.deVanessa.Vaessen@bgr.de

+49 (0)228 99 535 3705www.bgr.bund.de/EN/policyadvice-gw

GEUS (Geological Survey of Denmark andGreenland)

Øster Voldgade 10DK-1350 Copenhagen KDenmark

E-mail:

Phone: +45 38 14 20 00

web: www.geus.dk

Karen G. Villholth

kgv@geus.dk

D E N M A R K