190
8 Exercises: Fictitious Case Studies
8.3.6 Drainage Management
The local water board uses the tidal inlet of the harbor for draining purposes. in the adjacent
dike there is a tidal gate which opens passively during low tide and closes with the rising
water level. The inland water flushes the short tidal inlet of the harbor. An agreement exists
between the water board and the harbor authority to drain as much inland water through
the tidal gate as possible.
8.3.7 Tasks
1. Draw a sketch about the first steps to be taken.
2. Prepare a flow chart for the working process.
3. Write down the different argumentation lines why the different administrative bodies
might be reluctant to take the full responsibility for the current situation of the side
channel which is the access to the small harbor. How to overcome them?
8.4 Problem 3: Closure of a Bay
Due to the storm surges in the Middle Ages the area of many bays along the southern
North Sea coast was enlarged. Here, the exercise deals with the closure of the Ley Bay
(Fig. 8.3) which is part of East Frisia in north-western Lower Saxony. The description of
the exercise is taken from Ahlhorn (2009, p. 14):
The Ley Bay witnessed its largest extension approx. 600 years ago, as a consequence of severe
storm tides in the middle ages. Until the middle of the last century land reclamation works
were executed to increase the arable area for the inhabitants. In the 1950s the Ley Bay was
mainly shaped by economic drivers (Erchinger, 1970; Hartung, 1983; Janssen, 1992; Kunz,
1999). Approx. 10,000 ha were reclaimed and this new land was offered to inhabitants and
refugees of World War II. After the 1950s the effort to reclaim land from the sea decreased,
because of the diversification of working fields after World War II and the increase of the
effectiveness in agriculture. On the other hand, the problems with water management in the
hinterland around the Ley Bay intensified, the existing tidal channels silted up continuously.
Until 1985 the problems also affected the harbors around the Ley Bay which were dependent on
free access to the North Sea. Siltation had imposed increasing pressure on water management
and shipping, resulting in the installation of pumping stations with continuously increasing
performance. (Janssen, 1992)
In the 1960s a plan was developed to enclose the Ley Bay, because of sedimentation problems: limited access of ships to the harbors and limitation of the drainage of the hinterland.
The Master Plan for Coastal Protection of 1973 stated that the height of the main dike was not
sufficient (Nds. MELF, 1973). These enclosure plans were also mentioned in regional planning
programs. The first idea for the enclosure of the Ley Bay took into account different types of
8 Exercises: Fictitious Case Studies
8.3.6 Drainage Management
The local water board uses the tidal inlet of the harbor for draining purposes. in the adjacent
dike there is a tidal gate which opens passively during low tide and closes with the rising
water level. The inland water flushes the short tidal inlet of the harbor. An agreement exists
between the water board and the harbor authority to drain as much inland water through
the tidal gate as possible.
8.3.7 Tasks
1. Draw a sketch about the first steps to be taken.
2. Prepare a flow chart for the working process.
3. Write down the different argumentation lines why the different administrative bodies
might be reluctant to take the full responsibility for the current situation of the side
channel which is the access to the small harbor. How to overcome them?
8.4 Problem 3: Closure of a Bay
Due to the storm surges in the Middle Ages the area of many bays along the southern
North Sea coast was enlarged. Here, the exercise deals with the closure of the Ley Bay
(Fig. 8.3) which is part of East Frisia in north-western Lower Saxony. The description of
the exercise is taken from Ahlhorn (2009, p. 14):
The Ley Bay witnessed its largest extension approx. 600 years ago, as a consequence of severe
storm tides in the middle ages. Until the middle of the last century land reclamation works
were executed to increase the arable area for the inhabitants. In the 1950s the Ley Bay was
mainly shaped by economic drivers (Erchinger, 1970; Hartung, 1983; Janssen, 1992; Kunz,
1999). Approx. 10,000 ha were reclaimed and this new land was offered to inhabitants and
refugees of World War II. After the 1950s the effort to reclaim land from the sea decreased,
because of the diversification of working fields after World War II and the increase of the
effectiveness in agriculture. On the other hand, the problems with water management in the
hinterland around the Ley Bay intensified, the existing tidal channels silted up continuously.
Until 1985 the problems also affected the harbors around the Ley Bay which were dependent on
free access to the North Sea. Siltation had imposed increasing pressure on water management
and shipping, resulting in the installation of pumping stations with continuously increasing
performance. (Janssen, 1992)
In the 1960s a plan was developed to enclose the Ley Bay, because of sedimentation problems: limited access of ships to the harbors and limitation of the drainage of the hinterland.
The Master Plan for Coastal Protection of 1973 stated that the height of the main dike was not
sufficient (Nds. MELF, 1973). These enclosure plans were also mentioned in regional planning
programs. The first idea for the enclosure of the Ley Bay took into account different types of