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Groundwater resources under changing climatic conditions

Applicant Hunkeler Daniel
Number 125995
Funding scheme NRP 61 Sustainable Water Management
Research institution Centre d'hydrogéologie et de géothermie Université de Neuchâtel
Institution of higher education University of Neuchatel - NE
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.03.2010 - 31.08.2013
Approved amount 496'084.00
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All Disciplines (3)

Discipline
Hydrology, Limnology, Glaciology
Other disciplines of Environmental Sciences
Other disciplines of Earth Sciences

Keywords (3)

Groundwater; Alluvial aquifers; Climate Change

Lay Summary (German)

Lead
Grundwasserknappheit durch Klimawandel? Grundwasser spielt eine zentrale Rolle für die Wasserversorgung in der Schweiz. Wie wirkt sich der Klimawandel auf unterschiedliche Grundwasservorkommen aus? Was sind die Konsequenzen für die Wasserversorgung?
Lay summary

Hintergrund
Etwa 80% unseres Trinkwassers stammen aus dem Grundwasser, das zudem während Trockenperioden die Mindestabflüsse in den Flüssen sichert. Grundwasser wird durch Niederschlag und durch den Untergrund sickerndes Flusswasser gebildet. In Zukunft werden im Sommer weniger, im Winter dafür aber mehr Niederschläge erwartet. Zudem werden einige Flüsse aufgrund des Gletscherrückgangs in Zukunft im Sommer weniger Schmelzwasser führen.

Ziele
Wir wollen verstehen wie sich diese Veränderungen auf unterschiedliche Grundwasservorkommen in der Schweiz auswirken. Ein besonderes Augenmerk wird auf mögliche längere Trockenperioden gelegt. In trockenen Sommermonaten dürfte die verfügbare Wassermenge abnehmen. Da in dieser Zeit der Wasserbedarf am höchsten ist, kann dies lokal zu Wasserknappheit führen. Insbesondere kleinere Grundwasservorkommen könnten rasch versiegen. Grössere Grundwasservorkommen können dagegen als Speicher wirken: Sie nehmen den Niederschlag, der zukünftig im Winter in grösseren Mengen fällt, auf. In den darauf folgenden Trockenzeiten speist dieses Grundwasser dann einerseits die Flüsse, andererseits kann es für die Wasserversorgung genutzt werden. Um diese Zusammenhänge besser zu verstehen, werden Klimaprognosen und Modelle des Wasserhaushaltes miteinander verknüpft.

Bedeutung
Grundwasser ist die wichtigste Trinkwasserquelle in der Schweiz. Um die Wasserversorgung langfristig zu sichern, benötigen wir fundierte Entscheidungsgrundlagen und Kenntnisse wie sich der globale Wandel auswirken wird. Diese Studie ermöglicht es, Standorte mit geringen verfügbaren Wassermengen zu identifizieren, so dass rechtzeitig Massnahmen getroffen werden können.

Direct link to Lay Summary Last update: 01.03.2013

Lay Summary (French)

Lead
Pénurie d’eau souterraine due au changement climatique? L’eau souterraine joue un rôle primordial dans l’approvisionnement en eau de la Suisse. Comment le changement climatique se répercute-t-il sur différents gisements d’eau souterraine? Quelles en sont les conséquences sur l’approvisionnement en eau?
Lay summary

Contexte
Environ 80% de notre eau potable provient de l’eau souterraine. Elle assure également un écoulement fluvial minimal en périodes de sécheresse. L’eau souterraine est formée par les précipitations et par l’eau fluviale s’infiltrant dans le terrain. A l’avenir, il faut s’attendre à moins de précipitations en été, mais davantage en hiver. De plus, dans le futur, certaines rivières transporteront moins d’eau de fonte en raison du recul des glaciers.

But
Le but du projet est la compréhension de ces changements sur les différents gisements d’eau souterraine en Suisse. Une attention particulière est prêtée à d’éventuelles périodes prolongées de sécheresse. Il est en effet à prévoir que le volume d’eau disponible pendant les mois secs de l’été diminuera. Comme le besoin en eau atteint son maximum pendant cette période, cela peut conduire à des pénuries locales d’eau. Les petits gisements d’eau souterraine, en particulier, pourraient tarir très rapidement. De plus grands gisements peuvent par contre faire office de réservoir: ils accumulent les précipitations, à l’avenir plus fréquentes en hiver. Durant les périodes de sécheresse qui suivent, cette eau souterraine alimente d’une part les rivières; elle peut d’autre part être utilisée pour l’approvisionnement en eau. La combinaison de prévisions climatiques et de modèles de régime hydrologique améliorera la compréhension de ces relations.

Portée
L’eau souterraine est la source la plus importante d’eau potable en Suisse. Afin d’assurer à long terme l’approvisionnement en eau, il est nécessaire d’avoir des bases de décision et des connaissances fondées au sujet des effets du changement global. Cette étude permet d’identifier les sites à faible quantité d’eau disponible, afin de prendre des mesures en temps voulu.

Direct link to Lay Summary Last update: 01.03.2013

Lay Summary (English)

Lead
Groundwater shortage due to climate change? Groundwater plays a major role for water supply in Switzerland. How does climate change affect different groundwater resources? What are the consequences for water supply?
Lay summary
Background
Approximately 80% of our drinking water comes from groundwater, which also ensures a minimal stream flow during dry periods. Groundwater is formed by precipitation and river water seeping into the underground. In future, less precipitation is to be expected during the summer, but more in the winter. In addition, some rivers will carry less meltwater during the summer due to glacier retreat.

Objectives and methods
We want to understand what effects these changes will have on different groundwater resources in Switzerland. Potential longer dry spells will be of particular interest. It is to be expected that during the dry summer months, the available water volume will diminish. As the need is highest during this period, this could lead to local water shortages. Particularly small groundwater resources could dry up quickly. Large resources however can store the precipitation which will, in future, increase during the winter. During the following dry spells, this groundwater will then feed rivers, on the one hand, and can be used as a water supply on the other. In order to better understand this relationship, climate predictions and hydrological regime models will be combined.

Significance
Groundwater is the most important source of drinking water in Switzerland. We need a sound decision-making basis and knowledge on the future effects of global change, so that the water supply can be secured on a long-term basis. This study makes it possible to identify sites with only small available water volumes, so that measures can be taken in good time.

Direct link to Lay Summary Last update: 01.03.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Infiltration under snow cover: Modeling approaches and predictive uncertainty
Meeks Jessica, Moeck Christian, Brunner Philip, Hunkeler Daniel (2017), Infiltration under snow cover: Modeling approaches and predictive uncertainty, in Journal of Hydrology, 546, 16-27.
The influence of model structure on groundwater recharge rates in climate-change impact studies
Moeck C., Brunner P., Hunkeler D. (2016), The influence of model structure on groundwater recharge rates in climate-change impact studies, in Hydrogeology Journal, 24(5), 1171-1184.
Contribution of alluvial groundwater to the outflow of mountainous catchments
Käser Daniel, Hunkeler Daniel (2016), Contribution of alluvial groundwater to the outflow of mountainous catchments, in Water Resources Research, 52(2), 680-697.
Tuoritals as flexible alternative to GUIs: An example for advanced model calibration using Pilot Points
Moeck C., Hunkeler D., Brunner P. (2015), Tuoritals as flexible alternative to GUIs: An example for advanced model calibration using Pilot Points, in Environmental modelling & software, 66, 78-86.
Channel representation in physically based models coupling groundwater and surface water: Pitfalls and how to avoid them
Käser D. Graf T. Cochand F. McLaren R. Therrien R. Brunner P. 2013 (2014), Channel representation in physically based models coupling groundwater and surface water: Pitfalls and how to avoid them, in Groundwater, 52(6), 827-836.

Collaboration

Group / person Country
Types of collaboration
Rene Therrien Canada (North America)
- in-depth/constructive exchanges on approaches, methods or results
Pascal Ornstein, CREALP, Valais Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Markus Weiler, Universität Freiburg i.B. Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Jan Seibert, University of Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Volker Prasuhn, Agroscope Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events



Self-organised

Title Date Place
Klimaeinflüsse auf das Grundwasser 10.05.2014 Thun, Switzerland
Workshop on groundwater recharge and hydrological processes, comparison of approaches in hydrology and hydrogeology 25.10.2011 Ligerz, Switzerland

Knowledge transfer events



Self-organised

Title Date Place
Workshop on Groundwater and Climate Change with 51 participants from public authorities, consultants and researchers 11.05.2012 Solothurn, Switzerland

Communication with the public

Communication Title Media Place Year
Print (books, brochures, leaflets) Klimaeinflüsse auf Grundwassermengen, Aqua&Gas No 11, 2014 Western Switzerland German-speaking Switzerland 2014
Print (books, brochures, leaflets) Nachhaltige Wasserversorgung und Abwasserentsorgung in der Schweiz International German-speaking Switzerland Western Switzerland 2014
Other activities Meeting Working group "Groundwater and Climate Change" German-speaking Switzerland 2012
Talks/events/exhibitions Effect of climate change in alpine groundwater environments International 2011
Media relations: print media, online media Forscher ziehen Lehren aus der Trockenheit 20 Minuten German-speaking Switzerland 2011
Other activities Meeting "Begleitgruppe Grundwasserprojekte" German-speaking Switzerland 2011
Media relations: print media, online media Prognosen für die Dusche Horizonte SNF German-speaking Switzerland 2011

Associated projects

Number Title Start Funding scheme
169003 Water distribution 01.03.2017 Project funding (Div. I-III)
149126 River Floodplains 01.10.2013 Project funding (Div. I-III)

Abstract

Groundwater is the most important drinking water source in Switzerland with 40% originating from pumping wells in alluvial aquifers and another 40% from springs. Since water resources planning is carried out on a long time horizon, it is important to know how aquifers might respond to climate change and what the implications for groundwater availability are. Climate change could affect both direct recharge by rainwater/melt water infiltration and indirect recharge via surface water bodies. The period of low or no direct recharge may become longer due to drier and warmer summers and indirect recharge may diminish during summer due to lower flow rates in rivers caused by earlier snowmelt and disappearing glaciers. To what extent such changes diminishes the groundwater availability strongly depends on the characteristics of groundwater flow systems and their ability to “bridge” the period of low recharge due to their storage capacity. Alluvial aquifers are often tightly linked to rivers and hence groundwater levels may follow the altered hydrologic regime with little delay. The response of aquifers with predominant direct recharge may be very variable depending on the storage capacity of the aquifer. While larger aquifers with extensive cover layers may be affected little by summer drought periods, small and shallow aquifer may show a rapid decrease in spring discharge.The main objective of the project is twofold. On the one hand it aims at developing and testing methodologies to evaluate the response of aquifers to climate change with a special emphasis on the possible diminished groundwater availability during summer months and make them available to endusers. On the other hand, it aims at applying the methods to typical hydrogeological situations in Switzerland and identifying scenarios where groundwater flow systems are particularly vulnerable to drought conditions. The study locations were chosen such that typical aquifer types used for water supply in Switzerland are covered while taking into account other studies on the effect of climate change of aquifers that are underway in Switzerland to avoid duplication. Based on these criteria the project focuses on alluvial aquifers and springs in fissured environments (crystalline and clastic sedimentary rock) with an emphasis on alluvial aquifers due their high importance for water supply. However, results from related studies on karst aquifers in limestone regions will integrate in the project as well (Project GLACIKARST and AQUA-MONTANA). Since the effect of climate change not only depends on the aquifer type but also on climatic conditions (e.g. role of meltwater), two study areas at different altitudes were selected. The sites include the upper Emmental valley with large pumping wells of the city of Berne in an alluvial aquifer and springs used for local water supply, and the Zinal Valley which includes fissured springs in a crystalline environment as well as an alluvial aquifer both influenced by snow and glacier melt water.Regarding methods, the response of alluvial aquifers to climate change cannot be investigated by considering them in isolation because groundwater (gw)-surface water (sw) interaction often plays a crucial role in their functioning and hence the behavior of the upgradient catchment area has to be considered as well. Although, it would technically be feasible to simulate the soil water (sow)/surface water (sw)/groundwater (gw) dynamics with a fully distributed model, a hybrid modeling approach was chosen in order to avoid overparameterization and to propose a methodology that is also applicable to other sites with a reasonable effort. The methodology consists of the coupling of a semi-distributed hydrological model (PREVAH or GERM) to simulate the response of the non-glaciated/glaciated upland catchment upgradient of the alluvial plain to climate change with an integrated sow/sw/gw model (HYDROGEOSPHERE) to simulate the alluvial plain and adjacent zones including selected springs. The modeling tool will be applied to evaluate how the seasonal trends of groundwater levels and spring discharges are altered due to climate change and to evaluate the implications for water supply. Specifically, at the upper Emmental site, it will be evaluated to what extent the pumping rates have to be reduced during dry periods (as was already necessary during the 2003 heat wave!) in order to ensure minimal instream flow requirements. At the Zinal site, it will be evaluated if the springs continue to supply sufficient water for the mountain resort despite earlier not melt or if not, to what extent the alluvial aquifers in the valley could serve as an alternative water source during summer. Finally conclusions will be drawn regarding the effect of climate change on aquifer behavior and groundwater availability by integrating results from other studies in the same field including other PNR61 projects (Weingartner, Livingstone, von Gunten, Seneviratne/Zappa), several other national research projects (CCHydro, SNF Glacikarst) and European projects (GENESIS, ACQWA). In addition to scientific publications, a methodology to assess the drought vulnerability of springs to climate change will be developed. Endusers will be involved on different levels. Endusers have already been involved in the selection of the study areas and the definition of the water management issues to be addressed. They will participate in an enduser group to provide immediate input on the planned activities and will be part of the working group developing the guideline. Further interaction with enduser will be established via the joint advisory group of the EAWAG projects and workshops and seminars organized for practitioners in this context.
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