10 Ingression and Ascension of Saline Waters on the Polish Coast of the Baltic Sea
227
10.5 Conclusions
1. The characteristic feature of the Polish coast is the presence of brines of the Cl–
Na type within the Mesozoic strata, from where they ascend into the Cainozoic
aquifers (for example Kołobrzeg, Kamie´ n Pomorski, Darłowo, Łeba, D˛ ebki).
2. High piezometric pressure in the Mesozoic layers, deep erosional structures, and
presence of tectonic discontinuities result in the saltwater ingress into the younger
multi-aquifer complexes. Displacements and tectonic discontinuities within the
Mesozoic layers influence the groundwater circulation system and often result
in interferences between different aquifers. The brine ascension is supported by
the groundwater extraction at intakes in coastal towns.
3. Changes in the chemical composition of waters in this area are strongly affected
by human activity consisting of excessive exploitation of aquifers, mainly in the
1970s and 1980s. The process of saline water penetration into exploited aquifers
was most extensive at that time. At present, it has been significantly inhibited as
a result of reduced water extraction at the water intakes in this area.
4. Saline water ingressions from the Baltic Sea occur locally in shallow aquifers
only and have limited extent. Until now, they have occurred mainly in the coastal
regions, in holiday locations that are supplied with water from local groundwater
intakes. During the last 20 years, as a result of the decreasing extraction and
abandonment of many intakes located directly in the shore zone, as well as the
construction of new intakes outside the influence of the sea zone, (most often
from several to a dozen or so km from the shore), the phenomenon of ingression
has been halted. Sometimes, restoration of the natural equilibrium between saline
and freshwater is observed as it occurred in Gda´ nsk.
5. Young fossil waters, originating from the beginning of the Littorina transgression,
have been found only locally, within the deltaic series of ˙
Zuławy. A clarification
of the origin of saline groundwater along the Polish Baltic coast is required for
water resource protection and safe yield calculations for water intakes, including
the saltwater in baths.
10.6 Recommendations
Assessments of safe yields restricting degradation of fresh groundwater resources are
fundamental for the continuous safe exploitation of groundwater intakes in the coastal
zone. Therefore, issues of water quality are decisive in estimating safe exploitation
volumes in the coastal zone.
All water intakes are managed by well-organized enterprises, which seek to protect
the groundwater resources. New water intakes are located at a considerable distance
from the areas threatened with ingression or ascension of brine and saline water. In
some areas where water intakes were excluded from exploitation or water extraction
was significantly reduced (e.g., the region of Gda´ nsk), the process of groundwater
227
10.5 Conclusions
1. The characteristic feature of the Polish coast is the presence of brines of the Cl–
Na type within the Mesozoic strata, from where they ascend into the Cainozoic
aquifers (for example Kołobrzeg, Kamie´ n Pomorski, Darłowo, Łeba, D˛ ebki).
2. High piezometric pressure in the Mesozoic layers, deep erosional structures, and
presence of tectonic discontinuities result in the saltwater ingress into the younger
multi-aquifer complexes. Displacements and tectonic discontinuities within the
Mesozoic layers influence the groundwater circulation system and often result
in interferences between different aquifers. The brine ascension is supported by
the groundwater extraction at intakes in coastal towns.
3. Changes in the chemical composition of waters in this area are strongly affected
by human activity consisting of excessive exploitation of aquifers, mainly in the
1970s and 1980s. The process of saline water penetration into exploited aquifers
was most extensive at that time. At present, it has been significantly inhibited as
a result of reduced water extraction at the water intakes in this area.
4. Saline water ingressions from the Baltic Sea occur locally in shallow aquifers
only and have limited extent. Until now, they have occurred mainly in the coastal
regions, in holiday locations that are supplied with water from local groundwater
intakes. During the last 20 years, as a result of the decreasing extraction and
abandonment of many intakes located directly in the shore zone, as well as the
construction of new intakes outside the influence of the sea zone, (most often
from several to a dozen or so km from the shore), the phenomenon of ingression
has been halted. Sometimes, restoration of the natural equilibrium between saline
and freshwater is observed as it occurred in Gda´ nsk.
5. Young fossil waters, originating from the beginning of the Littorina transgression,
have been found only locally, within the deltaic series of ˙
Zuławy. A clarification
of the origin of saline groundwater along the Polish Baltic coast is required for
water resource protection and safe yield calculations for water intakes, including
the saltwater in baths.
10.6 Recommendations
Assessments of safe yields restricting degradation of fresh groundwater resources are
fundamental for the continuous safe exploitation of groundwater intakes in the coastal
zone. Therefore, issues of water quality are decisive in estimating safe exploitation
volumes in the coastal zone.
All water intakes are managed by well-organized enterprises, which seek to protect
the groundwater resources. New water intakes are located at a considerable distance
from the areas threatened with ingression or ascension of brine and saline water. In
some areas where water intakes were excluded from exploitation or water extraction
was significantly reduced (e.g., the region of Gda´ nsk), the process of groundwater