St.-Canisius-Delta


 * The Delta Works in The Netherlands

Here are some pictures of the Deltaworks from the Netherlands: By clicking on this link, the page will load in this window.** http://www.picturesofholland.nl/Deltaworks/frameset.htm


 * We searched some information for the students in Canada. This is the most important information.**

**History** Studies conducted in 1937 by Rijkswaterstaat (Department of Public Works), showed that safety in many parts of the Netherlands could not be guaranteed at times of storms and high sea levels. In the densely populated areas near the river mouths of the Rhine, the Meuse, and the Schelde, it proved very difficult to build new dikes or strengthen the original ones. The first solution was to close all the river mouths: the Western Schelde, the Eastern Schelde, the Haringvliet, and the Brouwershavense Gat. This proposal was christened 'the Deltaplan'. In 1950, the first river mouths of the Brieles' Gat and the Botlek were closed. The Brielse Maas became a freshwater basin. This not only made the area safer, but it also provided Voorne with a freshwater supply. The plan was to build the remaining dams in the following decades. Unfortunately though, the infamous flood of 1953 prevented this from happening. Nearly two thousand people died and more than 150,000 hectares of land were flooded. People soon became aware that something had to be done, and very, very quickly. Twenty days after the flood of 1953, the Delta commission was inaugurated. The commission would give advice about the execution of the Deltaplan, that would, in the long run, increase the safety of the Delta area. Although safety was the number one priority, the seaways De Nieuwe Waterweg and the Western Schelde would have to stay open, because of the economic importance of the ports of Rotterdam and Antwerp. In order to be able to build dams in the rivers' mouths, some auxiliary dams would first have to be built in the Zandkreek, the Krammer, the Grevelingen, and the Volkerak. These dams were known as 'compartment dams', since they would divide the large area of water into multiple compartments. In 1959, the Delta Law was passed, in order to organise the construction of the dams. The building of the 'Deltaworks' was such an enormous project, that it was sometimes referred to as the 'eighth wonder of the world' - and not without good reason. **First and second advice:** On May 16, 1953, the Deltacommission gave its first piece of advice: to raise the Schouwens Dike from 3 metres above NAP (Normal Amsterdam Water Level) to 5 metres above NAP. This was not included in the Deltaplan. The second piece of advice from the Deltacommission was to close down the river Hollandse IIssel. This advice was of great importance, because if the dikes along the river IIssel were breached, an industrialised area with over 1.5 million inhabitants would be in danger. It was suggested to close the Hollandse Ijssel by means of a storm surge barrier near the river’s estuary. A movable dam was chosen that is only closed in the case of a storm tide, so as to not harm shipping traffic, and reduce interference with the the water's flora and fauna. The advice for closing the Hollandse IJssel was given in the same year in which the flood took place. One year later, in 1954, building was initiated. **Third advice:** On February 27th, 1954, the Deltacommission gave its third piece of advice, in which they would focus on damming the sea arms. Closing the sea arms would cause coastal reduction, and reduce the number of places that the sea has a direct effect upon. Damming the Haringvliet, the Brouwerhavense Gat, the Eastern Schelde, and the Veerse Gat would prevent high water levels arising in the sea arms. The advantages of closing the tidal inlets Closing the tidal inlets had a number of advantages compared to raising the current dikes: 1. Raising the current dikes would be more expensive, more difficult, more dangerous, and less effective compared to damming the tidal inlets. 2. Damming the sea arms would prevent the water remaining brackish 3. Building dams between different islands would provide good connections with the rest of the Netherlands 4. Raising the current dikes would cost land, while building dams would actually reclaim a modest amount of land. 5. By implementing the Deltaplan, a unique recreation area would be created Firstly, in the case of raising the dikes, 1000 kilometres (!) of dikes would need to be raised. Since the sea level is continually rising, the dikes would need to be raised again after two years. Not only would the risk of flooding remain, but raising the dikes would also involve a lot of maintenance. By damming the sea arms, only some tens of kilometres of dunes, dikes and dams would remain, which means far less maintenance. Moreover, the raising of dams would be very easy to carry out. Secondly, water around the Zeeland islands would remain brackish in the case of raising the dikes. The Deltaplan (in the form of damming the sea arms) would prevent the water from remaining brackish, and a large freshwater basin would be created. This would have a positive effect on the entire Dutch freshwater economy, because of a good source of river water. Thirdly, by carrying out the Deltaplan, the islands would be connected to the mainland of the Netherlands via roads on top of the dams. In the case of raising the dikes, the islands would keep their isolated position. Another advantage of the Deltaplan is the modest reclamation of land, compared to raising the dikes. The dikes would be raised and broadened inland over a distance of hundreds of kilometres, which would have cost a large area of arable land. By building the dams, land is reclaimed. Carrying out the Deltaplan would also create a unique recreation area, something which would not be achieved by raising the dikes. The Deltaplan seems to be a plan with nothing but advantages. However, there is one big disadvantage: the crustacean and shellfish fishing industry would be lost. If closed, the Eastern Schelde would be supplied with fresh water instead of salt water. Mussels, oysters, and other crustaceans, and shellfish, cannot survive in freshwater. The Deltacommission therefore advises to investigate the possibility of moving the crustacean and shellfish to other places. On October 18th, 1955, the fourth and last piece of advice was given. This advice included an extensive specification of the Deltaplan, detailing the advantages and disadvantages and an overview of the costs. The Deltacommission believed that the Deltaplan could be carried out in 25 years and cost approximately 1.5 to 2 billion guilders (today about 680 to 900 million euros). The plan was commuted into a bill and on November 16th, 1955, the bill was sent to the Dutch Lower House. More than two years later, the law was enacted and, on May 8th, 1958, the Delta-law was signed by the Queen herself. They couldn’t build more then 1 construction at the same time. The government of the Netherlands decided to build the constructions in an order: from the smallest constructions to the largest. We did this because we could learn from previous constructions, so that the largest constructions would be the best. The experiences gained would be helpful for carrying out the most complicated parts of the Deltaworks. When determining the order, the materials and manpower available were taken into account. The Department of Waterways and Public Works also took into account that protection against storm tides would be number one priority. On the basis of these considerations, it was decided to carry out the Deltaworks in the following order: 1.  Storm surge barrier in the Hollandse IJssel 2. Damming the Zandkreek 3. Damming the Veerse Gat 4. Damming the Grevelingen 5. Damming the Volkerak 6. Damming the Haringvliet 7. Damming the Brouwershavense Gat 8. Damming the Eastern Schelde 9. Flood-control dam and lock in the Oude Maas
 * Last advice **
 * The works **

**
 * Overview dams:

Reason they started with the construction of the (as we called it) stormvloedkering in the hollandse IJssel the huge construction project started that will take several years. The stormvloedkering ensures there that the weak sea dikes along the Krimpenerwaard and Schieland superfluous are. **Position** the stormvloedkering in the river the hollandse IJssel were built. This state in connection with the sea and flows directly by lower lain shares of the Netherlands. For this reason it was also this way important that this river was concluded. **Construction** The dam exists from double flowing which each ± 670 weigh barrels. These were hung between two towers which were both 44 m. above BOWL. On the river side the flowing have been reinforced by means of a steel arc construction. At devising the stormvloedkering there also had be taken into account the shipping. For this reason there is a sheltsluice with a length of 120 meters and a breadth of 24 meters beside the stormvloedkering. Also one can travel now easy with the car of the Krimpenerwaard to the continent of south-Holland by a viaduct which has been introduced on the stormvloedkering. These have been named after to the minister of movement and water state Mr. Algera. **Beginning construction: 1954** weight 1 flow: 670 barrels altitude towers: 44 meters above BOWL length sheltsluice: 120 meters breadth sheltsluice: 24 meters length viaduct: 560 meters costs: 40 millions euros completed: October 1958
 * Hollandse IJssel [[image:waterkering.JPG align="right"]] **

**__Veersegatdam__** Reason The Veersemeer arised by the Veersegatdam and the zandkreekdam must develop himself in the first place to recreation area. Some areas are now natures areas. The Veersegatdam lies on the linker side of the Veersemeer and separates this more with the North sea. The dam lies on the spot where the earlier the Veersegat were. Hence also the name: Veersegatdam__.__ **Construction** The Veersegatdam was the first really build dam with difficulty. Through the Veersegat, as it happens, water passes at each tide approximately 70 millions m³. By this large quantity water and large strength of it builds a piece is more with difficulty if the two dams earlier built at. Preparations also more have been made than at the other dams. First an asphalt factory was put down. The dam has been, as it happens, held for the security and strength of, with a low asphalt. Also on site four menginstallations has been built there. By the large quantity water which comes at the dam could be used there none the ordinary caissons. Special caissons were devised: the doorlaatcaissons with dimensions of 45 meters long, 20 meters broad and 20 meters high. They have been built in a special for that moored area. In the caissons sit slide open that were then them in water were placed, but went after three days near. Also there houten drijfschotten on the longest sides sit. These obtained one, after the caissons fallen omit have to, and this way are possible it ebb and vloed by it unhindered gone flows. There no normal caissons could become used because these could not precise enough put aside by the large flow speeds. The dam himself sees as follows: On both sides dams have been moored. These are covert with a low asphalt, originating from for that the built asphalt factory. After the construction of the dams still a breach approximately 300 meters were. In this breach seven doorlaatcaissons were brought to sink. These became sink between thresholds on the floor, earlier introduced. In April 1961 the first box was brought to to sink. The last on 24 April. With stone and gravel beside the caissons strength is loved the tide flows under control. On 27 April steels slide were opened. move water by tide cycle: 70 millions m³ dimensions doorlaatcaissons: 45 meters long, 20 meters broad and 20 meters high first box placed: Beginning April 1961 last box placed: 24 April 1961 //__** **__//accomplished: October 1961//__**
 * Position **
 * __// Beginning construction: 1958

**Water** It is a cliché, but a true cliché: without water, we cannot survive. It is not only human beings who would be in danger without water, but also plants and animals would not survive. Although it is difficult to imagine the earth without water, it is not so obvious that there is not enough fresh water for everybody. Hundreds of millions of people do not have access to fresh drinking water and have to walk hundreds of kilometres to a water pump. It is not only a shortage of water that can cause trouble, a surplus of water can cause harm too. Just think about the great flood disaster of 1953 and the tsunami in Asia in January 2005.

To make use of the benefits water offers us, water must be managed. This applies to both the driest desert in Africa and the wettest coastal areas in the Netherlands. Before making any decisions, a good knowledge about the local area is vital. Without this knowledge, one can actually cause more harm than good. The natural balance can easily be distorted. A small change may have no immediate or visible effect, but it is difficult to predict what the effects will be in the future. Knowledge such as what water is, how it is divided up over the earth, how the tides work, and what the water cycle is, is indispensable. Holders of this knowledge can try to optimise the water functions, e.g. drinking water, irrigation water and the waterways. Water management makes it possible to combine water collection and water purification with human activities, such as living, working and recreating. Most importantly, nature should be preserved.

**Nature** When you think about the Deltaworks, the first things which probably come to mind are steel and concrete. However, the people who built the Deltaworks did not simply place the heavy constructions on the bottom of the sea. With regard to the Oosterschelde, for instance, the bottom was so weak that specially made mattresses filled with stones had to be placed on the bottom. Geological research was required in order to find out more about the layers of the earth. Within the following pages of this section, you will find more information about geology in general, the geology of the Netherlands, and the geology of the Delta region. The environment was very important too when considering the design of the Deltaworks. Some dams could only be closed during particular circumstances, i.e. when the tides and the winds were favourable. And you may almost forget: why were the Deltaworks built anyway? Exactly, because of flood disasters, caused by a combination of extreme weather conditions and spring tide. Knowledge of the weather and the climate is especially important when building something as large as the Deltaworks. The most advanced computer programmes were used to calculate the wind speeds and the currents, before the Maeslantkering and Oosterscheldekering could first be closed. Now the Deltaworks have been completed, research into (the change of) climates still has priority, since climate changes could have an effect on the sea levels. In the Netherlands, in which about half of the country lays below sea level, swimming is still a preferred solution to sinking. Lastly, the Dutch landscape and some serious (global) environmental problems will be discussed. The Dutch landscape has been influenced particularly during the last two thousand years, since humans entered the area. Three prominent types of landscape will be described: the sea clay landscape, the river clay landscape and the dune landscape. Moreover, four environmental problems will be discussed: the rise sea level, the dangers to fish, the depletion of the ozone layer and water pollution. All these problems have (indirect) effects on us. It is not too late though and we can do a lot to help by treating our environment responsibly.

**This is how the Maeslantkering works:**

** Stormsurge Barrier Oosterschelde Besides shortening the total length of the dikes by 700 kilometres, the Delta works had many other advantages. Firstly, the agricultural freshwater supply was improved. Because the border between freshwater and saltwater was moved further west, less freshwater was required to balance the freshwater-saltwater division. The excess water could be transported to the north of the Netherlands, in the direction of the Ijsselmeer (Ijssel lake), where extra freshwater was welcomed to improve the water conditions. Secondly, the complete water balance of the Delta area was improved. Thanks to the construction of the major and auxiliary dams, the streams in this area were able to be manipulated more easily. Different types of sluices made it possible to allow fresh water in, or polluted or excess water out.
 * Significance of the Deltaworks

Thirdly, the construction of the Delta works encouraged traffic between the many islands and peninsulas. Large parts of the province of Zeeland had literally been isolated for centuries. The building of the Zeeland Bridge together with a tunnel under the Westerscheldetunnel (2003), also helped increase mobility.

Hartelkering Fourthly, the inland waterways shipping was supported by the Delta works. In 1976, Belgium and the Netherlands signed a contract that would regulate the shipping between the ports of Antwerp and Rotterdam. Obviously, this agreement had to be taken into account when building the Delta works. Lastly, the Delta works have influenced new developments in the areas of nature and recreation. Understandably, a number of nature reserves were irreparably damaged, but as compensation, new nature reserves have emerged at different sites. Nowadays, dry shores are sometimes used as recreational areas. Whether or not nature has benefited from the Delta works will remain an unsolved debate. However, there is no doubt over the need for durable water management, in which safety, prosperity, and nature are taken into account.

On 21 February 1953, twenty days after the water disaster, a commission gets a task to prevent The Netherlands for another disaster. There are 2 choices: to raise and strengthen thousand kilometres dike length or to close a few tidal outlets. The some required that becomes are put that The Westerschelde and the Rotterdamse Waterweg open must remain, to guarantee Antwerp, Ghent and Rotterdam a good accessibility of the ports of. Between May 1953 and October 1955 the delta Commission presents five recommendations: - The Schouwense dike on Schouwen-Duiveland up to 5 meters above BOWL must be raised, in contrast to the rather mean 3.5 meters. The dike would lie with respect to the storm direction too unfavourable and must according to the Commission in emergency situations is able act as headwaterturn. - Locking of the Dutch IJssel appears necessary because the IJsseldijken threaten break through, as a result of which lives - and industrial area with wide 1.5 millions people danger runs. The delta Commission prefers a stormvloedkering: aggravating dikes costs more money, and the construction of such turn goes more rapidly. A year after this second recommendation from 1953 is started with construction. - Beginning 1954 recommends the Commission some concluding sea breaches to increase the security in Zuidwest-Nederland. Reinforcing the existing dikes is already no longer under discussion: a locking is both in technical and in economic respect feasible. Salt water will change however in sweet water, as a result of which the fishery experiences disadvantages to this plan. However, there are coming possibilities for recreation in the area and has the country - and horticulture sector sweetens water to its arrangement. The plan provides in the locking with the following sea breaches (from north to south): Haringvliet, Brouwershavense breach, Oosterschelde and Veerse breach. Furthermore there are plans for some lockings which have been situated Easterly: Volkerak, Grevelingen and sand creek. The sea defending dikes in sea country are brought back with this plan of 700 kilometres up to approximately 20 à 30 kilometres. - Locking Veerse breach and sand creek (also: three island plans). This way North - and south beveland and Walcheren with each other are joined. One considers the Veerse breach dam as preparation to the larger lockings which still stand that to wait, hence there on it is insisted fast to start. The experience which brings with the construction of this dam with itself can be used next for the remaining lockings. - The last recommendation includes a range of advantages and disadvantages the devised costs and a summary of the delta plan. One thinks the plan within 25 years is implement and that with that an amount of 1.5 up to 2 billion guilder involved (680 up to 900 millions Euro). After the Commission in October 1955 to be given has the last recommendation, submit it on 16 November of the same year a design of the delta law at the House of Commons. On 5 November 1957 the House of Commons accepts the bill, the Upper Chamber follows a day on 7 May 1958. Later signs queen Juliana the delta law, which definitively a fact is.

Further developments: The Deltaworks are build to support the dikes and the dunes. The existing dikes will get an extra ring, to increase the height of the dikes. The Deltaworks are build to prevent the Netherlands to overflow by a storm. The Netherlands form a high risk because of the V-shape of the Kanal. New plans: The new buildings who are build to prevent from overflow are build with big concrete pillars, they are attached to the bottom of the see. Over the pillars there lies a highway for traffic, the road is separated in several parts of concrete blocks. The pillars were very heavy and needed a strong underground. To prevent that the building would shake or move, they put the pillars 15 meter into the ground. A special tool was developed for this case, the Mytilus. This vehicle put long needles into the bottom and vibrated so that the ground would be better to build something on it. The project started in 1980 and ended in 1982. After that the bottom was strong enough to build a structure on it, they had to lay down mats to flatten the bottom. A special company build the mats of plastic and filled them with gravel. The mats were placed between November 1982 and June 1984. When the mats were placed the pillars could stand on the ground. In the first months of 1983 the pillars were ready to insert. The building docks were one by one filled with water so that a lift ship could lift the pillars up and put them in the right place. There were a total of 65 pillars placed.