Geoscience Reference
In-Depth Information
19.6 Conclusion
The assessment of coastal groundwater discharge can be estimated based on a bud-
get approach if groundwater recharge can be considered equal to total discharge, i.e.
no other sink terms exist. These assumptions are valid for most flat coastal catch-
ment areas of medium size at the southern Baltic coast. Then only the surface runoff
which drains through the surface water bodies (rivers) must be distinguished from
the direct exfiltration from the aquifers to the sea.
For the catchment (140 km
2
) in the vicinity of Wismar the groundwater recharge
is calculated as 146 mm/a which corresponds to 24.3% of the mean annual precipi-
tation of 600 mm/a; 14.3% exfiltrate as direct groundwater discharge, i.e. 12
.
10
6
m
3
/a. Similar values have been reported for Eckenförde Bay in the west (Schlüter
2004
). The residual 10% of groundwater recharge drains through the rivers to the
Baltic.
Small changes in precipitation result in a more pronounced change in ground-
water recharge, i.e. a 10% precipitation increase results in a 29% increase in
groundwater recharge. However, seasonal shifts of precipitation change, possi-
ble alteration of land use and changes in evapotranspiration rates are still to be
considered.
The predicted sea-level rise in the Baltic will have a major impact on many
aspects, e.g. socio-economy. However, groundwater discharge does not show sig-
nificant response to sea-level rise for the given hydraulic conditions at the test
site.
×
Acknowledgements
The authors are grateful for critical comments by Daniel M. Tetzlaff.
Comments provided by two reviewers and the editors helped to improve the manuscript.
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