Towards a Baltic Sea Region Strategy in Critical ... - Helsinki.fi

CRITICAL INFRASTRUCTURE PROTECTION IN THE BALTIC SEA REGION
observation well HP66 is located on the
south beach, about 215 m from the
Mannerheimintie water works and 50 m
from the coast.
The measurement was done using
the VanEssen Diver and VanEssen
Barometer tools (Figure 4). Pressure
and temperature were measured in
every 30 minutes in both diver sensor
and in air pressure sensors, which were
situated in the housing of the HP66
observation well. The groundwater
level was calculated from the pressure
in a diver sensor and was compensated
with air pressure. Sea level monitoring
data of the same period were received
from the Finnish Institute of Marine
Research. This data was measured
every hour.
The most important factors
controlling the sea level in the Baltic
Sea are air pressure, wind, water flow
through the Danish Straits, and ice
conditions in winter. According to FIMR
(2007), tide has an effect of only a few
centimetres on the Finnish coast. The
Figure VI—4 Groundwater monitoring tool
installation at the well
HP0306. (Photo by S.
Luoma)
currents flow through the Danish Straits, caused by sea level differences between
the Baltic Sea and the North Sea, and can cause a change in the total amount of
water in the Baltic Sea (bathtub effect). The air pressure is one of the main factors
that affect the sea level. An air pressure change of 1 mbar corresponds to a sea
level change of 1 cm. The normal pressure variations may thus cause a sea level
variation of several tens of centimetres.
6.3 HANKO AQUIFER
Hanko study area
The topography of the Hanko Peninsula is relatively low and the average altitude
is only about 13 m a.s.l. (N 60 ) (Figure 5). The studied 14 km 2 sand and gravel area,
the Hanko aquifer, is a part of the First Salpausselkä end moraine and the altitude
in the area of this formation is about 10 – 12 m increasing slowly towards
northeast. The general feature of the aquifer is flat plain shelving to the seaside on
its south and northwester side.
The study area belongs to the town of Hanko, which lies partly on top of the
aquifer under study. Hanko has about 10 000 inhabitants and an area of about 800
km 2 . The economy consists of 60 % services and 38 % industry. The town has a
busy port, mainly handling transit trade to Russia, and many chemical industries.
198 NORDREGIO REPORT 2007:5