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On a cold and stormy morning in January 1953, the Princess Victoria ferry was preparing
to leave its dock in Stranraer on the south-west coast of Scotland, despite gale warnings.
An hour into its journey its captain radioed for help as the storm forced the ferry on
its side, making it impossible to board the lifeboats.
Of the 176 people aboard the princess victoria, only 43 survived, but there was more tragedy
to come, this storm was headed south towards the Netherlands, pushing the seas with it,
and with the Moon and Sun causing even higher tides, this storm would severely test the
flood defences of the Netherlands, which was still getting back on its feet after the Second
World War.
The storm would ultimately claim the lives of 1,835 people in the Netherlands, along
with 200,000 cattle and flooding 2,000 square kilometres of land, destroying 43,000 homes
forcing and 72,000 people to flee.
Today, we are going to learn why this happened and how it would spark the construction of
one of the seven modern wonders of the world: The Dutch Delta Works.
After World War 2, the meandering levees on the coast of the Netherlands had fallen into
disrepair, the Netherlands were just getting back onto their feet after 5 years German
occupation just 8 years prior to the storm.
The poorly maintained flood defences were a disaster waiting to happen.
As the storm approached, it forced water inlands with no-where to go, but up.
This put intense pressure on the dykes and levees of the low countries, and by the storm’s
end 139 kilometres of levees would be heavily damaged, with holes up to 3.5 kilometres being
torn open.
With nearly 26% of the Netherlands land area being under sea level, seawater burst through
these breeches with immense strength causing damage that would take decades to repair and
would spur the formation of the Delta Committee just 20 days later to ensure this could never
happen again and this is what they came up with.
The new Delta plan would shorten the Dutch coastline by 700 kilometres, by closing the
primary inlets in these 4 locations, this would drastically reduce the length of levees
and dykes that needed to be inspected and maintained and thus decreasing the chances
of weak points jeopardising the safety of the Dutch people.
However this was no easy task and would come with an enormous cost.
Before these works could be completed, additional barriers needed to be erected upstream to
improve fresh and saltwater management, and prevent fresh water emptying from the Rhine,
Meuse and Schelde river from redirecting around these new dams.
The northern most closure dam also needed to be equipped with a hydraulic sluice capable
of dealing with the output of the Rhine river, as this Fresh water would flood the Netherlands
from the other direction, if it was prevented from emptying into the North Sea.
On top of all this, a number of ports, such as the port of Rotterdam and the port of Antwerp,
had to stay accessible.
So, aside from fixed dams, bridges and sluices, two new locks that would allow an inland ship
route between Antwerp and Rotterdam needed to be built.
Amazingly, on top of all this work, the dutch still managed to consider the environmental
impact of this work.
The largest of the structures built for the Delta Works project, the Oosterschelde Storm
Surge Barrier, was originally planned to completely close the mouth of this river, which would
create a fresh water basin.
However resistance to this plan arose, as it would completely change the saltwater environment
of the area.
The Oosterschelde scenery is unique, with a great variety of fish, water plants and
animals.
So in 1976 the Dutch government agreed to a different plan: Building an open barrier
that could be closed during heavy storms and high tides.
adding another 2.5 billion euros to the cost to the project.
This barrier is 9 kilometres long with 62 openings, each 40 metres wide, allowing the
tidal movement to remain in tact.
To build a structure this massive, that needs to not only support it’s own weight, but
the enormous force of a storm surge pushing against it, would require extensive foundations.
The first part of these foundations were created by forming two islands, the biggest of which
housing a lock to allowing ships to pass through the barrier.
This island even included a massive dry dock to construct the 65 pylons needed to support
the sluice gates, each using 7,000 cubic metres of concrete and taking one-and-a-half years
to build.
Between each island a trench was dug.
On both sides of the trench, mats were placed to keep the seabed in place.
While specially built ships were then used to consolidate the sand at the bottom of the
trench, using special vibrating needles, the sand would be vibrated to pack the sand firmly
together creating a surface that could carry the weight of the massive pylons.
The trench itself was then covered with specially made mats filled with rocks to help prevent
erosion of the underlying sand.
The pylons were left hollow so they could be picked up by another purpose-built, u-shaped
ship, and moved into place.
There, inside the trench, on top of the mats, they would be lowered, filled with sand and
closed with concrete.
The wide foot of each pylon was packed in stone, as it is vital the pylons never move,
because if even one of the massive, 260 to 480 tonne doors, cannot move, the current
in that location could become enormous and potentially damage the structure.
Finally these enormous hydraulic pistons were attached to the sluice gates, allowing 3 kilometres
of the 9 kilometre long Storm Surge Barrier to open and close on demand.
This project truly is one of the modern wonders of the world.
Allowing the dutch to rule the tide and ensure the chances of another devastating flood are
dramatically reduced, but with sea levels continuing to rise and warmers seas causing
even stronger storms, we need to remind ourselves of the lessons learned here.
The flooding of New Orleans in 2005 occurred for many of the same reasons as the 1953 flooding
of the Netherlands.
Poorly maintained levees broke well below their design tolerances, allowing 80% of the
city to be flooded in just 5 hours.
Had New Orleans taken lessons from history and reduced the length of defences needed,
as they have done now with the 1.1 billion dollar Lake Borgne Surge Barrier, they may
have saved of over 1000 people and prevented the 108 billion dollars of damage the storm
caused.
If these trends continue cities around the world are going to have to seriously assess
the risk of flooding and make plans to prevent any chance of a flood taking the lives of
their citizens.
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