Geoscience Reference
In-Depth Information
The Swedish Meteorological and Hydrological Institute (SMHI) has calculated
four future climatic scenarios and three sea-level heights up to the year 2100 for the
Baltic Sea region based on two driving global models from the Hadley Centre (HC)
and the Max Planck Institute for Meteorology (MPI) which are combined with the
two IPCC emission scenarios (A2 and B2). Accordingly three sea-level scenarios
for the southern Baltic, 0.24, 0.41 and 0.82 m, and four precipitation scenarios, +1%
(MPIA2), +10% (MPIB2), +5% (HCA2) and -1% (HCB2), of recent precipitation
rate are predicted.
The German coast of the Baltic has received much attention with respect to the
dynamics of sea levels (Harff et al. 2005 ). However, the impact of climate change on
the water budget of coastal aquifers in this region has not yet been attempted. The
general mechanisms of aquifer response to changing climatic conditions at a typi-
cal till-dominated coastline still need to be investigated. An existing medium-scale
groundwater flow model at the Wismar Bay (Darsow 2004 ) serves as an example
site. The intention of this study is to provide a general understanding of the aquifer
response at the southern Baltic. Here the relative importance of sea-level rise and
changing groundwater recharge conditions on the amount of coastal groundwater
discharge is of major interest.
Based on an existing calibrated groundwater flow model (FE model 'Catchment',
Darsow 2004 ) the specific goals are (i) to quantify groundwater discharge for a typ-
ical medium-scale catchment area at the southern Baltic border for today's climatic
conditions, (ii) to calculate groundwater discharge in the same catchment for dif-
ferent combinations of the predicted sea levels and precipitation rates and (iii) to
analyse the change in groundwater discharge during a period of 100 years of increas-
ing precipitation rates and/or rising sea level by means of transient simulation for a
simplified model (FD model 'Simple').
19.2 Materials and Methods
A simple balance concept is used to derive the long-term submarine groundwater
discharge rate from the hydrologic budget equation. This equation is applied to a
coastal catchment at the border of the Baltic Sea. A groundwater flow model is
calibrated for recent climatic and hydrologic conditions with respect to sea level
and aerially varying groundwater recharge. Based on this, steady-state conditions
of predicted climatic scenarios are calculated and the change in submarine ground-
water discharge is determined. Finally a simplified FD model is used to analyse the
development of submarine groundwater discharge for transient conditions.
19.2.1 Balance Concept
The global long-term water budget is given by Eqs. ( 1 ) and ( 2 )
P
=
ET
+
Q
(1)
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