60
4 Hydrology of (Shallow) Coastal Regions
• Installing pumping stations to convey the excess water from the hinterland to the sea
where no natural hydraulic gradient is available
• Constructing storm surge barriers to protect the tidal rivers against high water levels
and to reduce the length of the dike system
All of these solutions have been implemented in practice in central Europe for a long time.
For further details see Sect. 5.1.2.
Applying a drainage management to an originally wet landscape certainly has implications on the landscape itself and on its water bodies.
The protection against the sea water excludes the natural hydrological dynamics from
the related coastal regions. Sedimentation, which was the vital process during the landscape development, does not happen anymore. Salt concentrations in soils and water
bodies are reduced by dilution processes caused by rainfall, infiltrating water and ground
water recharge. The geochemical environment is changing fundamentally. The aeration of
the marsh soils caused by drainage accelerates mineralization processes, which together
with de-calcification is the reason for soil subsidence.
The drainage of water bodies leads to adjusted and constant water levels in the water
bodies. The water bodies in the marsh area are no longer exposed to the tidal dynamics.
While such constant levels are advantageous for anthropogenic use of the landscape, the
hydrological nature of the water bodies is suppressed. To ensure the hydraulic function
of the water bodies, regular dredging and maintenance is required. The consequence is
that, according to the European Water Framework Directive (WFD, EC 2000), such water
bodies are classified either as heavily modified water bodies or even as artificial water
bodies.
In terms of flood risk the respective areas are protected by dikes, allowing anthropogenic activities and long-term investments. But, however, a 100 % safety through
such technical protection systems does not exist. Therefore, according to the European
Flood Risk Management Directive (FRMD, EC 2007) these coastal areas are classified as
high-risk areas. In case of failure of the protection systems, large areas might be flooded.
In addition to the today’s water management challenges, climate change is expected to
aggravate an efficient water management (Bormann et al., 2012). Due to a rising sea level,
an intensification of the terrestrial water cycle (increase in heavy rainfalls in frequency and
intensity) at least temporarily more water will have to be drained against a higher sea level
(Fig. 4.13). Similarly, salt intrusion is expected to be more severe than today.
As a consequence, in our days, adaptation to climate change is required, and traditional water management needs to be checked against future drainage requirements and
innovative solutions (Bormann et al., 2015).
Exercise
1. Large parts of the coastal areas are protected by dikes. That implies that many inland
water bodies are regulated by water management. Which hydrological processes
4 Hydrology of (Shallow) Coastal Regions
• Installing pumping stations to convey the excess water from the hinterland to the sea
where no natural hydraulic gradient is available
• Constructing storm surge barriers to protect the tidal rivers against high water levels
and to reduce the length of the dike system
All of these solutions have been implemented in practice in central Europe for a long time.
For further details see Sect. 5.1.2.
Applying a drainage management to an originally wet landscape certainly has implications on the landscape itself and on its water bodies.
The protection against the sea water excludes the natural hydrological dynamics from
the related coastal regions. Sedimentation, which was the vital process during the landscape development, does not happen anymore. Salt concentrations in soils and water
bodies are reduced by dilution processes caused by rainfall, infiltrating water and ground
water recharge. The geochemical environment is changing fundamentally. The aeration of
the marsh soils caused by drainage accelerates mineralization processes, which together
with de-calcification is the reason for soil subsidence.
The drainage of water bodies leads to adjusted and constant water levels in the water
bodies. The water bodies in the marsh area are no longer exposed to the tidal dynamics.
While such constant levels are advantageous for anthropogenic use of the landscape, the
hydrological nature of the water bodies is suppressed. To ensure the hydraulic function
of the water bodies, regular dredging and maintenance is required. The consequence is
that, according to the European Water Framework Directive (WFD, EC 2000), such water
bodies are classified either as heavily modified water bodies or even as artificial water
bodies.
In terms of flood risk the respective areas are protected by dikes, allowing anthropogenic activities and long-term investments. But, however, a 100 % safety through
such technical protection systems does not exist. Therefore, according to the European
Flood Risk Management Directive (FRMD, EC 2007) these coastal areas are classified as
high-risk areas. In case of failure of the protection systems, large areas might be flooded.
In addition to the today’s water management challenges, climate change is expected to
aggravate an efficient water management (Bormann et al., 2012). Due to a rising sea level,
an intensification of the terrestrial water cycle (increase in heavy rainfalls in frequency and
intensity) at least temporarily more water will have to be drained against a higher sea level
(Fig. 4.13). Similarly, salt intrusion is expected to be more severe than today.
As a consequence, in our days, adaptation to climate change is required, and traditional water management needs to be checked against future drainage requirements and
innovative solutions (Bormann et al., 2015).
Exercise
1. Large parts of the coastal areas are protected by dikes. That implies that many inland
water bodies are regulated by water management. Which hydrological processes