The North Sea Protection Works

For many, the image out of the Dutch fight against the North Sea rests in the
figure of a young boy valiantly saving his town by using a finger to plug a hole
in the dike. But this familiar hero is a fictional one, a creation of American
author Mary Mapes Dodge in her book, Hans Brinker. In reality, heroism falls on
all the Dutch, who for more than a millenium have been wresting precious
agricultural lands from the sea and fighting to hold on to them. Their greatest
achievement-a colossal fun in the dike-if the vast and one dress project known
as that Netherlands North Sea protection works.

Because much of the Netherlands lies below sea level, normal tides would
daily inundate about half the country if previous generations of industrious
Dutch had not raised dikes and dams. Severe storms often cause tidal waters to
crash into the dikes and inundate rivers and estuaries. Although all of the
coastal areas are threatened, two particularly vulnerable ones are the large
tidal inlet formerly known as the Zuider Zee and the delta created by the Rhine
and Meuse rivers in the southwestern corner of the country.

Dutch engineers purse propose that the Zuider Zee be dammed and drained in
the 19th century, but the government was reluctant to tackle such an immense
project. Then, in 1916, a furious storm hit the northern provinces. The
difficulties of wartime agricultural production were compounded, and the way was
paved for the damming of the Zuider Zee.

The dam enclosing the Zuider Zee was built in two sections using traditional
materials. Beginning in 1923, workers laid boulder clay in parallel layers and
filled the space in between with sand, stones, and handmade, mattresses
fashioned from brushwood. To curtail erosion, larger mattresses ballasted with
chains and stones were sunk in the estuaries channels. Dredges, cranes,
tugboats, and barges were engaged in the erection of the main dam, 300 feet wide
at sea level and 25 feet high at the level of its causeway. As the tide turned
on the final day of construction, fill tumbled into the dam's last gap,
transforming the inlet into a freshwater lake, renamed the Ijsselmeer. The
finished dam contains sluices for draining excess water and locks for
maintaining shipping.

After the damming came the draining. In all, more than a half million acres
of polders, or reclaimed farmland, emerged from the bottom of the former Zuider
Zee. Young Dutch farmers clamoring for the right to settle the new polder lands,
because farms on new, unobstructed land were far more suitable for modern,
mechanized farming methods than traditional farms in older areas.

In 1953, the "storm of the century" howled across the North Sea and
into the Netherlands, testing the strength of the Zuider Zee enclosure. It held,
with damage to the causeway heavy in places. The country's unprotected
southwestern provinces felt the full brunt of the storm, with water surging over
seawalls and up the delta's wide waterways. More than 1,800 people lost their
lives, and livestock numbering in the hundreds of thousands perished. The
country then realized that the long-intended plan to safeguard the southwestern
delta, the Delta Plan or Delta Project, must be mobilized.

The plan would undergo a many incarnations. The last one involved a damming
four estuaries in the middle of the delta while leaving open channels to
Rotterdam in the north and Antwerp, Belgium, in the south. A two-mile-long surge
barrier in the Oosterschelde estuaries was the most complex and sophisticated
piece of the project.

Originally, the Oosterschelde was to be a closed barrier. But lobbying by
fishermen and conservationists resulted in the switch to a movable barrier. To
facilitate construction, engineers fashioned islands on three sandbars in the
estuaries and constructed work harbors, material yards, and work sites there. A
dam connected two of the islands, effectively creating three channels in the
estuaries, each to receive a section of the surge barrier.

The movable barrier consists of 65 concrete piers weighing 18,000 tons
apiece. The piers support 300- to 500-ton steel gates and their hydraulic
machinery, as well as a roadway above and load-bearing beams below. Constructed
on the work islands, the piers and their mechanisms had to be lifted into
precise positions in the estuary. But the type of equipment needed for such
gargantuan and specialized tasks did not exist anywhere in the world; it had to
be invented.

The Oosterschelde barrier also honored traditional methods. As part of the
measures taken to stabilize the sea floor, mattresses were laid under each pier
to prevent erosion. They were not the hand-built weaving of trees and brush used
to close the Zuider Zee, however. Instead, they were high-tech sandwiches of
sand and gravel between space-age fabric covers. The Oosterschelde project
finished in 1986. Since then, the Dutch have taken additional measures,
including the completion in 1997 of the barrier that protects the port of
Rotterdam.

"In terms of magnitude," an American trade journal wrote, the North
Sea project "approaches of the Great Wall of China. In terms of complexity
and technical sophistication, it approaches the lunar shot. It is unique,
expensive, and quite unlike any other civil engineering project to be found on
this planet."