How the Netherlands Defends the Largest Port in Europe Against Flooding

Following the North Sea Storm of 1953, which submerged most of the province of
Zeeland and a portion of the South Holland province (see http://www.semp.us/biots/biot_317.html), the government of the Netherlands seriously began to study the problem of flooding in the Netherlands. This Biot is about controlling flooding affecting the Port of Rotterdam, the second largest port in the world.

Rotterdam is located about 30 miles due east of the North Sea, in the interior of the province of South Holland, as depicted in the map below. In spite of its interior location, Rotterdam is a huge port, the largest in Europe and, until recently, the largest in the world.

Rotterdam specializes in petrochemicals and general cargo transshipment handlings for transport of bulk and other goods between the European continent and other parts of the world. From Rotterdam, goods are transported by ship, river barge, train or road. Large oil refineries are located west of the city. The rivers Meuse and Rhine, when followed eastward, also provide excellent access to deep inside Europe. Not surprisingly, Hitler launched a blitzkrieg against Rotterdam in May 1940, almost bombing it to extinction. It has since been rebuilt.

Locating Rotterdam

The Port and City of Rotterdam are located on the banks of the river Nieuwe Maas, one of the streams in the delta formed by the Rhine and Meuse Rivers arriving there from the hinterlands. Nieuwe Maas corresponds to the letter “n” in the following satellite image of the north delta area of Zeeland and South Holland.

As River Nieuwe Maas makes its way west towards the North Sea, it changes its name to River Scheur (see “s” on the image), and then again changes its name to Nieuwe Waterweg, a manmade canal completed in 1872 (see letter “t” on the image). The Nieuwe Waterweg has enjoyed continuous building out to include the “Europort” and the “Maasvlakte” near its mouth where it empties into the North Sea (letter “y” on the above image).

During the flood of 1953, the storm surge from the North Sea sped eastward up the Nieuwe Waterweg to the River Scheur, and from there to the River Nieuwe Maas. A tributary of the River Nieuwe Maas is named the River Hollandse IJsell. When the storm surge met the outflowing Hollandse IJsell waters, the river water became pent up with no place to go. Along the west side of the Hollandse IJsell is a dike named the Groenendijk. The Groenendijk was all that lay between the roiling waters of the colliding storm surge and the Hollandse IJsell waters, and the densely populated province of South Holland.

When the Groenendijk gave way, in spite of the valiant efforts of many men to strengthen it in the early hours of February 1, 1953, the local mayor commanded the captain of a ship called “The Two Brothers” to wedge his vessel into the breach, which he did and saved South Holland from the horrendous flooding affecting the province of Zeeland to the south. To track the storm surge of the North Sea Storm of 1953, visit: http://www.mapquest.com/maps/map.adp?city=Rotterdam&country=nl; accessed January 11, 2006.

The Delta Works

Intent on preventing a recurrence of the storm surge barreling into Zeeland and South Holland again, the government of the Netherlands conceived and deployed an ambitious flood defense system called the “Delta Works”, comprising 13 different flood control structures (see http://www.deltawerken.com/English/10.html?setlanguage=en). The names of these 13 Delta Works are: Hollandse IJssel 1958: The Zandkreek 1960; The Veerse-Gatdam; The Grevelingendam; Vokerakdam; Hellagatsplein 1969; Haringsvlietdam 1970; Brouwersdam  1972; Markiezaatskade  1983; Oosterschelde  1986; Oesterdam 1987; and Philipsdam 1987 (see:
http://library.thinkquest.org/C001635F/engdeltawerken1.htm; accessed January 11, 2006).

The goal of the Delta Works was to reduce the miles of dikes exposed to storm surge. The way to accomplish this, the experts concluded, was to close the mouths of rivers with dams or emplace moveable flood control structures that could be deployed when a North Sea storm surge threatened Zeeland or South Holland provinces. The Nieuwe Waterweg, however, could not be closed off because of its economic importance. The Maeslant structure was the solution (described below).

The Delta Works is vast and is sometimes called the Eighth Wonder of the World. Only two of the flood control structures of the Delta Works are described here: the Hollandse IJsell storm surge barrier and the Maeslant storm surge barrier, because they control potential storm surges threatening Rotterdam. Keep in mind the intent and immense scale of these flood control structures in comparison to anything that we have in the United States.

The Hollandse IJsell Storm Surge Barrier: The First Structure Built

By 1958, just five years after the 1953 storm, the first storm surge barrier was completed 
in the river Hollandse IJsell. Recall that this river is a tributary flowing into the Nieuwe Maas and along its banks is the Groenendijk dike, which gave way just as the captain of “The Two Brothers” ship was able to wedge it into the dike to occlude the breach during the 1953 storm surge.

The Hollandse IJsell is a barrier and not a dam, and its importance is vast: it separates Rotterdam from the North Sea and thus protects the densely populated western part of the Netherlands, now known as the Randstad, against future flooding. The Randstad is an agglomeration of four large cities and their surrounding areas, and contains more than 7 million residents, which is almost half the population of the Netherlands. It includes Rotterdam, Amsterdam, The Hague, and Utrecht, among many other municipalities. (For more on the Randstad, see: http://en.wikipedia.org/wiki/Randstad.) The Randstad sits on very low-lying land.

The Hollandse IJsell storm surge barrier works by lowering two weirs or gates into the river to prevent storm surge water from entering the mouth of the Hollandse IJsell and spreading over or through the dike system into Rotterdam and beyond. A lock for ships of a certain size is alongside the barrier. The barrier remains open except during testing or during a storm of sufficient magnitude. For more information on this barrier, please go to:
http://www.deltawerken.com/Hollandse-IJssel-storm-barrier/322.html.

The Maeslant Storm Surge Barrier

The flood of 1953 really shook up the Dutch. In addition to the Hollandse IJsell storm surge barrier placed in the mouth of the Hollandse IJsell River to protect Rotterdam, another much larger and more complex flood control structure, called the Maeslant storm surge barrier, was built between 1991 and 1997 in the mouth of the Nieuwe Waterweg. This new structure made raising the dikes around Rotterdam unnecessary anymore as theoretically the storm surge from the North Sea would be stopped by the Maeslant storm surge barrier before it ever had a chance to move up the channel. A good video of the Maeslant barrier is available at: http://www.deltawerken.com/Maeslant-barrier/330.html; accessed January 11, 2006.

How the Maeslant Works

“During water levels of [9 feet] above Amsterdam ordnance zero, the arms of the barrier are activated. The waterway, with a width of [about 1,180 feet], can then be closed completely. At first sight, it is almost unbelievable that such a barrier is capable of such an achievement. The Maeslant barrier is almost as long as the Eiffel tower and weighs about four times as much. It is the only storm surge barrier in the world with such large moveable parts. The storm surging doors have a length of [780 feet] each. Under normal circumstances, these doors are fully opened, so that the ships have access to the port of Rotterdam. The doors are stored in docks with a length of [689 feet], which lie along both shores.” (http://www.deltawerken.com/The-functioning/463.html.)

“During storm tide the docks are flooded and the hollow doors begin to float. They are driven into the water by means of a small train. This lasts for about half an hour. When the doors are situated in the middle of the river, valves are opened and as a result the doors are flooded. Consequently, the doors sink to the bottom because of their weight. On the bottom, there is a concrete threshold. A lot of silt gathers on this threshold. To close the New Waterway properly, arms need to be positioned exactly on the threshold. The doors do not sit directly on the threshold yet, but are hung a little above them. The current under the doors becomes so strong that the silt is washed away. After about an hour, the doors can sit flat on a silt-free threshold. The water level on the seaside is then higher than the water on the riverside. The force against the surging wall during a storm is about 350 Mega Newton: this is equal to the weight of 350,000 strong men, carrying 100 kilograms each. The pressure difference is so large that a ship of equal measurements would capsize instantly. The unique shape of the barrier prevents this from happening.” (http://www.deltawerken.com/The-functioning/463.html.)
 
In conclusion, the North Sea Storm of 1953 caused extensive loss of life and property in the Netherlands, especially in Zeeland and south South Holland provinces. As a result the government undertook a long-term project called the Delta Works to seal off or otherwise control the flow of water at the mouths of rivers. In this way, the pressure would be taken off of local levee systems during a severe storm surge. Thirteen projects have been completed to date, including two specifically to protect Rotterdam.