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Hanko study area

  1    Pre-foresight

The Hanko case study focuses to research impacts of climate change on a shallow groundwater formation located in the sea shore of the Baltic Sea in Southern Finland. The Hanko cape consists of relatively low sand and gravel deposits- the altitude is on average only 13 meters above sea level. The water supply of 10 000 inhabitants, industry and harbour areas in Hanko is based completely on the fresh water of this formation.

Today the impact of sea level fluctuations on the groundwater already exists, causing problems concerning both water quantity and quality in the wells of the water works. All the underground infrastructure of the town is especially sensitive to changes in groundwater level.

The goal in the Hanko case study is to create a structural model of the groundwater body and to model the groundwater flow. Also climate change scenarios will be applied. This gives tools to manage the water resources better. It is planned to develop a backup-plan safeguarding water supply under changing climate conditions.

  • Data collection – spring 2010
  • Establishing of a groundwater flow model including climate change impacts – end of 2010
  • Preparing potential development scenarios and conduct a workshop in Hanko – end of 2010
  • Preparing a back-up plan to safeguard water supply in Hanko – summer 2010

  2    Data and inputs

In the very beginning all available data for the modelling are compiled. Data are asked and collected from all the organizations operating in the study area: Geological Survey of Finland, Hanko city, Uusimaa Regional Environment Centre, Finnish Road Administration, Port of Hanko, VR- Finnish Rail Transport Company, Finnish Defence Forces, and all local industries. Field studies including geophysical methods are going to be completed and some groundwater observation wells are installed in areas, where no data is available. The primary groundwater modelling will be done with GMS software.

So far, all available data for the groundwater modelling has been utilized and some new geological and geophysical data, concerning the structure of the aquifer has been produced and in addition one new groundwater observation tube has been installed. Also the monitoring data of fluctuation in groundwater table and groundwater quality has been produced in twelve groundwater observation tubes. The three-dimensional geological and groundwater flow modelling of Hanko cape aquifer has been constructed from the geological and geophysical data, utilizing the integration of ArcGIS/ArcInfo and Groundwater Modeling Software (GMS).

  3    Information transmission

As a result of the groundwater modelling representative maps and animated sequences are prepared to illustrate the current state of the aquifers in Hanko and to give an idea of a potential future conditions taking into account climate change.

Within in the frame of the BaltCICA project a set of potential development scenarios for Hanko is going to be developed. The scenarios include information provided by climate change models and the groundwater modelling performed in Hanko. But the scenarios take into account also potential development paths in population, industries and society.

  4    Interaction

Adaptation to climate change is still a new issue in Hanko and only few things have been done. In the BaltCICA-project Hanko will develop together with the Geological Survey of Finland a set of adaptation options. The options will be jointly assessed and compiled in a back-up plan.

In September 2010 a workshop was organized, of which participants include stakeholders and citizens' representatives. The workshop utilized the potential development scenarios for Hanko to discuss with the participants the scenarios' significance and create visions for Hanko's development with a special focus on water supply.

  5    Output

If relevant, adaptation measures are implemented still within the project time. Other measurement can be implemented, when certain thresholds (sea level, groundwater level, salt concentration) are exceeded or undercut.

The results can be utilized in similar geological formations in other regions of Baltic Sea. The adaptation options will be discussed in a workshop and an excursion for water supply experts from the Baltic Sea Region.

Report: Ground water conditions and water suply in the future, the Santalaranta waterworks in Hanko (Pohjavesiolosuhteet ja vedenhankinta tulevaisuudessa Hangon Santalanrannan vedenottamon alueella)

Involved Persons

Geological Survey of Finland: Birgitta Backman, Samrit Luoma, Michael Staudt, Johannes Klein

Hanko Water and Wastewater Works: Kimmo Paakkonen

Hanko aquifer is surrounded by the Baltic Sea. Photo: S. Luoma


The study area is a sand and gravel formation. Photo: S. Luoma


Groundwater level is automatically monitored with a tool measuring the pressure and temperature. Photo: S. Luoma


Solid model of Hanko aquifer Quaternary layers (green) lying on the crystalline bedrock (red) (S. Luoma).