Geoscience Reference
In-Depth Information
to the long-term mean sea level at the Baltic Sea coast is given by Meier et al.
(
2004
). There are three effects: (i) the isostatic uplift of the land, (ii) the eustatic
sea-level rise and (iii) the water balance of the Baltic Sea (Johansson et al.
2003
). In
addition other effects are described (Sherif and Singh
1999
), i.e. the expansion of the
ocean due to a warm-up and the melting of ice sheets and glaciers will increase the
total volume of the ocean, and both processes will have a big impact on sea level.
However, climate change will also affect groundwater resources by the change in
rainfall intensity and geographical distribution of rainfall resulting in a change in
groundwater recharge (Sherif and Singh
1999
).
Not all effects and resulting impacts to the geosphere are adequately understood
at the moment but due to the importance of groundwater as a major resource of
global water source they cannot be neglected. Groundwater discharge is a key factor
controlling water table conditions, surface and groundwater quality, lake levels and
baseflow of rivers and streams.
Recently the contribution of terrestrial groundwater and its potential load of
nutrients and other contaminants are increasingly discussed, but little is known on
the variety of discharge processes and how they depend on geological and hydroge-
ological conditions. However, it is expected that groundwater discharge will change
quantitatively and qualitatively in response to changes in land use, groundwater
recharge, groundwater management and civil engineering hydraulic activities in
coastal areas induced by climate change (IPCC
2007
).
Different approaches are currently used to quantify groundwater discharge; either
the direct outflow is measured in situ or the submarine groundwater discharge is
quantified as a component of the coastal water budget. In the first approach seepage
meters are used to measure discharge rates and to collect samples in order to assess
the hydrochemical composition. However, the support of this method is limited to
meter scale or less. Balancing the water budget, on the other hand, yields spatially
integrated values, which may be useful in order to predict total mass loads. In this
study the latter approach is followed.
The northern border of the state of Mecklenburg-Vorpommern comprises 340 km
of the southern Baltic coast. It shows all characteristics of a typical simplification
coast with its long sandy bars and lagoons (e.g. Island Usedom) and its steep slopes
of glacial tills (e.g. Island Poel). It is therefore the result of a long and highly
dynamic geological history which started with the Littorina transgression (7,800
years BP) and is still ongoing. As a consequence the coastline, which builds the
interface between the brackish sea water and the terrestrial fresh water (surface and
subsurface), has moved landwards (Meyer
2003
). This process still holds on.
The discussion on the future evolution of the sea level and its consequences is
receiving more and more attention. Within the framework of the IPCC (Special
Report on Emission Scenarios) 40 standard scenarios (SRES) of greenhouse gas
emission have been published for the period from 1990 until 2100. The SRES
scenarios are based on various estimates of demographic and socio-economic
developments. Four groups of scenarios, A1, A2, B1 and B2, are distinguished
(Nakicenovic et al.
2000
) and transferred to the regional conditions in the Baltic
Sea region (Meier et al.
2004
).
