The is a

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

located in the Grevelingen sea

inlet An inlet is a typically long and narrow indentation of a shoreline such as a small arm, cove, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In ...

between

Schouwen-Duiveland Schouwen-Duiveland () is a municipality and an island in the southwestern Netherlands province of Zeeland. The municipality has 33,737 inhabitants (1 January 2016) and covers an area of (of which is water). The northside of the island has two fi ...

and

Goeree-Overflakkee Goeree-Overflakkee () is the southernmost river delta, delta island of the Provinces of the Netherlands, province of South Holland, Netherlands. It is separated from Voorne-Putten and Hoeksche Waard by the Haringvliet, from the mainland of North ...

The Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

. The Grevelingendam was the fourth structure constructed as part of the

Delta Works The Delta Works () is a series of construction projects in the southwest of the Netherlands to protect a large area of land around the Rhine–Meuse–Scheldt delta from the sea. Constructed between 1954 and 1997, the works consist of dams, slu ...

. The dam is six kilometres in length. Construction began in 1958 with the aim of delivering it in 1964. Due to several setbacks, the construction of the dam took seven years and was opened on 1 April 1965 by Minister of Transport and Water Management,

Jan van Aartsen Johannes "Jan" van Aartsen (; 15 September 1909 – 3 February 1992) was a Dutch jurist and politician of the Anti-Revolutionary Party (ARP). There is a

navigation lock A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a chamber in a permanently fixed position i ...

at the southern end of the dam near Bruinisse, and nearby a

control lock A control lock, guard lock or stop lock differs from a normal canal lock in that its primary purpose is controlling variances in water level rather than raising or lowering vessels. A control lock may also be known as a tide lock where it is used ...

using a

siphon A siphon (; also spelled syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, abo ...

system, known as the , which connects the

Eastern Scheldt The Eastern Scheldt () is a former estuary in the province of Zeeland, Netherlands, between Schouwen-Duiveland and Tholen on the north and Noord-Beveland and Zuid-Beveland on the south. It also features the largest national park in the Net ...

with the Grevelingenmeer. The construction of the Grevelingendam permitted Dutch

civil engineers This list of civil engineers is a list of notable people who have been trained in or have practiced civil engineering Civil engineering is a regulation and licensure in engineering, professional engineering discipline that deals with the desi ...

and contractors to gain experience that would be necessary for the Brouwersdam, along with more complicated closure works such as those at the

Haringvlietdam The Haringvlietdam, incorporating the Haringvliet sluices, are hydraulic engineering structures which closed off the estuary of the Haringvliet, Netherlands, as part of the Delta Works. The structure consists of 17 sluices, several kilometres of da ...

, and the

Oosterscheldekering The Oosterscheldekering ( English: Eastern Scheldt storm surge barrier), between the islands Schouwen-Duiveland and Noord-Beveland, is the largest of the Delta Works, a series of dams and storm surge barriers, designed to protect the Netherlan ...

Feasibility, planning and design

Being part of the Delta Works scheme, the Grevelingendam works were conceived in response to the

North Sea flood of 1953 The 1953 North Sea flood () was a major flood caused by a heavy storm surge that struck the Netherlands, north-west Belgium, England and Scotland. Most sea defences facing the surge were overwhelmed, resulting in extensive flooding. The ...

, as a result of which it was decided to close the inlets in

Zeeland Zeeland (; ), historically known in English by the Endonym and exonym, exonym Zealand, is the westernmost and least populous province of the Netherlands. The province, located in the southwest of the country, borders North Brabant to the east ...

and

South Holland South Holland ( ) is a province of the Netherlands with a population of over 3.8 million as of January 2023 and a population density of about , making it the country's most populous province and one of the world's most densely populated areas. ...

. The Grevelingendam was not a specific requirement of the Dutch Delta Act of 1958 and is not primarily intended to protect against flooding. Rather, as was the case with two other Delta Works projects (the Volkerakdam and the Zandkreekdam), the Grevelingendam was designed as a secondary compartmentalisation dam with the goal of reducing tidal current velocities in four surrounding

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

, thereby permitting easier subsequent construction of the primary dams of the Haringvlietdam, the Brouwersdam and the Oosterscheldekering. The location of the dam had a major influence on the construction schedule. The dam is founded over much of its length on a sandbank known as the , which dries out at low tide. Between the south side of the dam and the

lock Lock(s) or Locked may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainme ...

, which is situated on the

bank A bank is a financial institution that accepts Deposit account, deposits from the public and creates a demand deposit while simultaneously making loans. Lending activities can be directly performed by the bank or indirectly through capital m ...

of Schouwen-Duiveland, the dam crosses a

gully A gully is a landform A landform is a land feature on the solid surface of the Earth or other planetary body. They may be natural or may be anthropogenic (caused or influenced by human activity). Landforms together make up a given ter ...

up to 25 metres in depth. Between the north side of the and the bank at Goeree-Overflakkee, the dam crosses a shallower, 1000 metre-wide network of gullies. The height of the western part of the dam (the 'crown line') over the is 5.5 metres above

Amsterdam Ordnance Datum Amsterdam Ordnance Datum or ' (NAP) is a vertical datum in use in large parts of Western Europe. Originally created for use in the Netherlands, its height was used by Prussia in 1879 for defining ', and in 1955 by other European countries. In the ...

(, NAP). This high crest line is necessary due to large

wave In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from List of types of equilibrium, equilibrium) of one or more quantities. ''Periodic waves'' oscillate repeatedly about an equilibrium ...

run-up, with the dike designed to permit some

flooding A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civi ...

at very high water levels. Space was reserved on the crown of the dam for the conversion of the N59 into a four-lane

motorway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...

, with a parallel road for other traffic. Due to a policy change in the 1970s, the four-lane motorway was never built. The hydraulic investigations undertaken at the design stage had shown that it was desirable to have the closure of the southern channel at the Schouwen-Duiveland coast precede the closing of the northern channel near Goeree-Overflakkee. The following construction schedule was therefore planned: * 1961: Construction of the dam section on the and commencement of works in the southern channel. * 1962: Closure of the southern channel and construction of the dam section through it. Commence construction in the northern channels. * 1963: Closure of the northern channels and construction of the dam section.

Construction: Southern channel caisson closure

The dam closure at the southern channel was achieved using a system of caissons, with a number of the caissons that had been used for the emergency closures immediately after the North Sea flood disaster of 1953 repurposed for use. In addition to new caisson units made specially for the Grevelingendam project, a caisson unit which had been intended for use on the closure of the Brielse Maasdam in 1950 was also used. The caissons were floated to the closing gap, being transported in units of five. Before the closure, abutments were placed on both sides of the dam, composed of two caissons on the south side and three caissons on the north side, which were connected to the top of the dam sections. When closing large gaps using caissons, the units must be placed in the closing hole during

slack water Slack tide or slack water is the short period in a body of tidal water when the water is completely unstressed, and there is no movement either way in the tidal stream. It occurs before the direction of the tidal stream reverses. Slack water c ...

, which in most cases occurs at the moment of tidal reversal (at or around the times of high water and low water). However, in the Grevelingenmeer, there were more than two turnarounds as a result of the fact that the

currents Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (hy ...

in the closing gap were influenced by tides from the

Oosterschelde The Eastern Scheldt () is a former estuary in the province of Zeeland, Netherlands, between Schouwen-Duiveland and Tholen on the north and Noord-Beveland and Zuid-Beveland on the south. It also features the largest Oosterschelde National Pa ...

and the Brouwershaven Gap. The flow velocities in the closing area were therefore analysed and calculated in detail for the various caisson sinking phases, using the

Deltar The Deltar (, English language, English: ''Delta Tide Analogue Calculator'') was an analog computer, analogue computer used in the design and execution of the Delta Works from 1960 to 1984. Originated by Johan van Veen, who also built the in ...

analogue computer, which had just been developed at the time. The time available during the turnaround made it impossible to sink the caissons individually. Therefore, two or three caissons were connected together and sunk at the same time. During the sinking manoeuvres, the caissons were guided by a firmly

anchor An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ', which itself comes from the Greek (). Anch ...

floating crane Floating may refer to: * a type of dental work performed on horse teeth * use of an isolation tank * the guitar-playing technique where chords are sustained rather than scratched * ''Floating'' (play), by Hugh Hughes * Floating (psychological phe ...

. After they had been sunk, armourstone was installed along the front and rear of the caissons by a stone dumping vessel (on the sea side of the dam) and a floating crane on the river side. After pouring

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

to the caisson units, the remaining elements were placed using a

floating sheerleg A floating sheerleg (also: shearleg) is a floating water vessel with a Crane (machine), crane built on shear legs. Unlike other types of crane vessel, it is not capable of rotating its crane independently of its hull. There is a huge variety in ...

. The unit caissons had a height of 6 metres, with the extensions being 2 metres in height. The threshold level at the closing gap was around 5 metres below sea level (Amsterdam Ordnance Datum) with the concrete barrier terminating 8 metres above this.

Construction: Northern channel closure using cable-way

The shallow nature of the northern channel permitted a more gradual closure, with the use of a 1.9 kilometre long

cable car Cable car most commonly refers to the following cable transportation systems: * Aerial lift, such as aerial tramways and gondola lifts, in which the vehicle is suspended in the air from a cable ** Aerial tramway ** Chairlift ** Gondola lift *** ...

system. The advantage of a gradual vertical closure is that flow velocities are limited, resulting in a reduction in the magnitude of

scour Scour may refer to: Hydrodynamic processes * Hydrodynamic scour, the removal of sediment such as sand and silt from around an object by water flow ** Bridge scour, erosion of soil around at the base of a bridge pier or abutments via the flow ...

holes either side of the dam. Another advantage of the cable car solution was that only a single pylon was required in the centre of the channel. The cable car system was designed by Rijkswaterstaat in combination with the French company Neyrpic, and used self-propelled cars and a

one-way system One-way traffic (or uni-directional traffic) is traffic that moves in a single direction. A one-way street is a street either facilitating only one-way traffic, or designed to direct vehicles to move in one direction. One-way streets typicall ...

to optimise capacity. A threshold at the base of the dam in the northern channels was poured in 1962, along with a dike section from Goeree-Overflakkee. The remaining length, of approximately 1200 metres, was constructed by the cable car method. The cableway consisted of two carrying cables, with the last sections terminating at a

turntable A phonograph, later called a gramophone, and since the 1940s a record player, or more recently a turntable, is a device for the mechanical and analogue reproduction of sound. The sound vibration waveforms are recorded as corresponding phys ...

, along which the cars could pass from one side to the other. The cables were attached to a fixed anchor point on the north-east side of the closure, which has been preserved as a monument to the construction, and to a tilting counterweight on the opposite side. The units and stone placed by the cars were transported by four steel

hopper barge A hopper barge is a type of barge commonly designed to transport commodities like coal, steel, rocks, sand, soil and waste. 'Hopper barge' can also refer to a barge that dumps cargo at sea. These are now commonly called 'split hopper barge', bec ...

s, being lifted and lowered by the cars. A production rate of 360 tonnes of stone per hour was achieved. The channels were closed using the method of gradual closing, partly because loosely packed sand in the substrate could lead to settlement issues, and partly to gain experience with the use of a cable-way. Using the cable-way stone was dumped on a threshold covered with

fascine mattress A fascine mattress , literally sink piece), is a large woven mat made of wikt:brushwood, brushwood, typically willow twigs and shoot (botany), shoots, used to protect riverbeds and other underwater surfaces from Hydrodynamic scour, scour and er ...

es,

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

foil, and asphalt mastic. The stone dam was built up in this way to 2.5 metres above NAP, after which sand could begin to be sprayed against the closing dam by dredgers, and the dam body raised. By the autumn of 1965, the Grevelingen Dam was completed.

The Grevelingenmeer (Lake Grevelingen)

With the Grevelingendam complete, the subsequent construction of the Brouwersdam in 1971 created the Grevelingenmeer

Lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

, which has become a popular water sports location for recreational

diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), ...

and

sea kayaking A sea kayak or touring kayak is a kayak used for the sport of Watercraft paddling, paddling on open waters of lakes, bays, and oceans. Sea kayaks are seaworthy small boats with a covered deck and the ability to incorporate a spray deck. They trad ...

Shipping Freight transport, also referred to as freight forwarding, is the physical process of transporting commodities and merchandise goods and cargo. The term shipping originally referred to transport by sea but in American English, it has been ...

enters the Krammer via the Grevelingen navigation lock at Bruinisse. In order to maintain the

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

status of the Grevelingenmeer, a

control lock complex was constructed in the Brouwersdam, and later a similar structure was constructed at the Grevelingendam (the ). These locks turned out to have more capacity than originally intended, and a decision was made to allow the Grevelingenmeer to remain as a

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

lake, it thus becoming the largest seawater lake in Europe. A connection to the

Philipsdam The is a compartmentalisation dam constructed as part of the Delta Works in the Netherlands. It separates water of the lakes Krammer (Netherlands), Krammer and Volkerak from the Oosterschelde, and connects the Grevelingendam to Sint Philips ...

was made at the

end of the Grevelingendam.

Road and bridge over the dam

The N59 runs over the Grevelingendam, with a secondary bridge constructed over the Grevelingen lock to cope with increased traffic volumes.

Media

File:Gondelvaart Grevelingendam, de gondel met net, Bestanddeelnr 916-5586.jpg, The cable car system in operation on the northern closure File:Grevelingen afgesloten vier caissons (reportage), Bestanddeelnr 913-9124.jpg, Caissons used in the construction File:Grevelingedam-02.jpg, The navigation lock located within the dam structure at the southern end File:Flakkeese Spuisluis.jpg, The control lock and sluice complex, adjacent to the dam

References

{{Authority control

External links

Grevelingendam at the Watersnoodmuseum knowledge centre
Information on the Grevelingendam from the official Watersnoodmuseum website Dams in Zeeland Dams in South Holland Dams completed in 1965 Delta Works