Water balance in the North Sea and Amsterdam-Rhine Canal
The North Sea Canal and the subsequent Amsterdam-Rhine Canal were originally created for shipping. Due to their common and equal water level, both together form a canal system that has become an important element in the water balance in the Netherlands . The adjacent water boards feed water from the drainage of the lower-lying polders into the canal system and this must be drained into the North Sea together with the water from the sluice processes so that the canal water level does not exceed permissible. Today the discharge only takes place via the sluice structure and the pumping station in IJmuiden . In addition, the Amsterdam-Rhine Canal plays an important role in securing the drinking water supply for the region and the province of North Holland and plays an important role in supplying fresh water to agriculture in periods of drought.
Structures of the canal system
Rijkswaterstaat (RWS), the executive authority of the Dutch Ministry of Infrastructure and the Environment for the construction and maintenance of roads and waterways, is responsible for the construction, operation and maintenance of the canals . The RWS authority ensures that the water level in the canal system is kept at NAP -0.40 meters (NAP = Normaal Amsterdam Peil = Amsterdam level ). This water level corresponds to a level below sea level . In times of long, high North Sea water levels, the water level may be 10 centimeters higher at NAP -0.30 meters.
North Sea Canal (NS-K)
The North Sea Canal is the most important shipping canal for seagoing vessels between IJmuiden on the North Sea and the capital Amsterdam with its large port . The 21 km long canal was built in the second half of the 19th century to give the port of Amsterdam a short connection to the sea. Over time, the canal, which was opened in 1876, was deepened and widened several times. Behind the port area of Amsterdam, the NS-K merges eastward into the inland IJ, which ends after 7 kilometers at the IJ dam.
The former IJ bay of the Zuiderzee was used to build the NS-K and polded in up to the planned canal route . For the drainage canals that had flowed into the IJ by then, a total of 10 side canals were left open when the polders were polded in to create a connection to the new canal. At the crossings, pumping stations convey the water from the polders into the canal system. The larger side canals have locks for shipping.
The sea locks in IJmuiden form the western end of the NS-K. Currently (2019) four locks are in operation and a new one is under construction. With a length of 500 meters and a width of 70 meters, the latter will be the largest lock in the world. The main structure of the lock system for the water balance is the transmission canal ( Spuikanaal ) with the sluice ( Spuisluis ) and the pumping station ( Gemaal ).
On the east side of the NS-K, the IJ dam between the Inner IJ and Outer IJ ( Buiten-IJ ) forms the end. The three Orange Locks from 1872 and the Prince Willem Alexander Lock, which opened in 1995, allow barges to pass through the Markermeer and on to the IJsselmeer . The water level in the Markermeer, which is always higher today, means that water is fed into the canal system during the locks. In addition to the south lock at the Oranjeschleusen, a separate through-channel was laid out for completion in order to divert water into the Zuiderzee at low tide . Today this channel is used for the targeted introduction of water from the Markermeer.
Amsterdam-Rhine Canal (ARK)
At the IJ dam in front of the Oranjeschleusen, the Merwede Canal has been branching south since the end of 1892 . Its expansion and extension in the middle of the 20th century resulted in the 72-kilometer-long ARK, which gave inland shipping free travel to the Rhine and Germany.
After 59 kilometers, the canal route in Wijk bij Duurstede reaches the Lek , where two locks form the end of the dewatering. Behind it, the canal route continues south to Tiel an der Waal and thus reaches the Rhine-Maas Delta . Due to the constantly higher water levels in the Lek estuary of the Rhine, the excess water always drains into the canal system during the sluice operations. The incoming fresh water is used to flush the sewer system and the drinking water supply .
Lekkanal
As part of the ARK, the four-kilometer-long Lek Canal has been branching off south of Utrecht near Nieuwegein since 1938 . It creates a short connection to the Lek and via it to Rotterdam . The double lock that was built at the time forms the end of the dewatering, which was supplemented by a third lock in 2019. These locks also feed the excess water into the canal system.
The sewer system in numbers
| Amsterdam-Rhine Canal | Lekkanal | North Sea Canal | |
|---|---|---|---|
| length | 59 km (to the Lek) | 4 km | 21 km (up to the IJ) |
| width | 100 to 120 m | 100 m | 270 m |
| depth | 6 m | 4.5 m | 15 m inland IJ: 11 m |
| surface | 8,073,570 m 2 | 20,523,670 m 2 | |
| Level, aimed at | NAP -0.40 m | ||
| Maximum level | NAP -0.30 m | ||
Water balance - entry
Water input from polder areas
The discharge of water from the surrounding land is the main input source for the canal system. In order to make the areas below sea level and thus in the groundwater usable, the Dutch built polders with dykes all around and drained the areas through ditches and canals. Wind-powered pumps were built to pump the water into the sea - the windmills still in large numbers today and the symbol of the Netherlands.
This task was and is vital for the existence of the Netherlands. For this reason, it was seen as a national and communal task very early on and assigned to special water associations . These associations, known as Waterschapen or Hoogheemraadschapen , are the oldest form of self-government in the Netherlands, dating back to the 13th century. As a result of mergers, a total of 21 Waterschapen exist today , which take care of the water management in the respective region across all provinces .
The polder areas of the provinces of Utrecht , North Holland and South Holland lie on both sides of the NS-K and ARK routes . Four waterschapen ensure that the collected groundwater and rainwater are transported away through a large number of pumping stations :
- Hoogheemraadschap Hollands Noorderkwartier (HHNK) in the province of North Holland
- Hoogheemraadschap van Rijnland (HVR) in the provinces of North Holland and South Holland
- Hoogheemraadschap Amstel, Gooi en Vecht (HAGV) in the provinces of North Holland and Utrecht
- Hoogheemraadschap De Stichtse Rijnlanden (HDSR) in the provinces of South Holland and Utrecht
List of major pumping stations
| Surname | place | Output [m³ / sec.] |
introduction | Coordinates |
|---|---|---|---|---|
| Hoogheemraadschap Hollands Noorderkwartier | ||||
| Gemaal Kadoelen | A'dam-Kadoelen | 11.6 | Side channel I | 52,409 ° N 4,909 ° E |
| Gemaal Overtoom | Westzaan | 3.0 | Side channel E | 52,431 ° N 4,784 ° E |
| Zaangemaal | Zaandam | 25.0 | Side channel G | 52,439 ° N 4,826 ° E |
| Gemaal De Waker (Barndegat) | Zaandam | 6.1 | Side channel H | 52,430 ° N 4,862 ° E |
| Hoogheemraadschap van Rijnland | ||||
| Boezemgemaal Spaarndam | Spaarndam | 38.0 | Side channel C | 52,411 ° N 4,674 ° E |
| According to Noodvijzel | Spaarndam | 5.0 | Side channel C | 52,411 ° N 4,674 ° E |
| Boezemgemaal Halfweg | A'dam West Gate | 33.0 | America port | 52,392 ° N 4,771 ° E |
| Hoogheemraadschap Amstel, Gooi en Vecht | ||||
| Gemaal Zeeburg | A'dam-Zeeburg | 60.0 | Lozings Canal | 52,367 ° N 4,953 ° E |
| Gemaal Stadwijck | Amsterdam-Zuid | 2.1 | Amstel | 52,336 ° N 4,905 ° E |
| Picture De Ruiter | Vinkeveen | 5.0 | Fearfulness | 52,220 ° N 4,973 ° E |
| Gemaal Noorderlegmeer | Uithoorn | 4.3 | Amstel | 52,244 ° N 4,849 ° E |
| Gemaal Middelpolder | Amstelveen | 5.4 | Amstel | 52,312 ° N 4,904 ° E |
| Gemaal Bovenkerkerpolder | Nes a / d Amstel | 4.5 | Ringsloot | 52,272 ° N 4,878 ° E |
| Hoogheemraadschap De Stichtse Rijnlanden | ||||
| Picture Caspargouw | Cothen | 3.3 | ARC | 51.985 ° N 5.26 ° E |
| Gemaal Galecop | Nieuwegein | 5.6 | ARC | 52,055 ° N 5,102 ° E |
| Gemaal Haarrijn (2014) | Breukelen | 3.8 | ARC | 52,146 ° N 5,014 ° E |
The large number of pumping stations with an output of less than two cubic meters per second is not listed. Every year around 2 billion m³ of water enter the sewer system via all pumping stations . Source:
Water entry from locks
Due to the sluice operations in IJmuiden, depending on the tide, water is discharged from the NS-K or North Sea water is brought in. Since the channel level is below the mean sea level is usually a water entry. One problem is the penetrating North Sea water, which leads to salinisation of the canal water. The resulting brackish water is not suitable for further use.
For details see: Brackish water problem
The water level in the Markermeer is 20 centimeters higher in summer than in the NS-K. Because of the strong inflows in winter, the level is kept lower during this time and is then only slightly higher than in the NS-K. If the water level differs between three and eight centimeters, the lock gates at the Oranjeschleusen can remain open so that the locks can be passed through unhindered. As a result, fresh water is always brought into the Oranjeschleusen today. The water helps flush the Amsterdam canals and creates counter pressure as the brackish water from IJmuiden penetrates . When the lock is in operation, the separate sewer next to the south lock provides the necessary water supply. During the renovation work on the Oranjeschleusen, this passage was given a new lock with a lifting gate that is remotely controlled by the control center for the water drainage in IJmuiden.
The water level on the Lek is always significantly higher than in the ARK, so that all locks on the Lek ensure an inflow of fresh water. This also creates a counter pressure and prevents salt water from penetrating from IJmuiden.
Every year, around 1 billion m³ of water are discharged into the canal system through the locks .
List of locks
| Name of the lock | Year of commissioning |
Usable length [meters] |
Width [meters] |
Drilling depth [meter] |
Lock loss [cubic meters] |
|---|---|---|---|---|---|
| IJmuiden lock complex (lifting height 0.20 meters) | |||||
| Small lock | (1876) 1999 | 111 | 11 | 3.75 | 244 |
| South lock | (1876) 1999 | 111 | 18th | 8.00 | 400 |
| Middle lock | 1896 | 225 | 25th | 10.00 | 1,125 |
| Nordschleuse | 1929 | 400 | 50 | 15.00 | 4,000 |
| New sea lock | 2022 | 500 | 70 | 18.00 | 7,000 |
| Orange locks (lifting height 0.20 meters) | |||||
| Nordschleuse | (1872) 2000 | 72.8 | 14th | 4.50 | 204 |
| Middle lock | (1872) 2000 | 95.2 | 18th | 4.50 | 343 |
| South lock | (1872) 2000 | 72.8 | 14th | 4.50 | 204 |
| Prince Willem-Alexander lock | 1995 | 200 | 24 | 5.20 | 960 |
| Amsterdam-Rhine Canal (lifting height 1.80 meters) | |||||
| Princess Irene Lock West | 1952 | 350 | 18.0 | 12 | 11,340 |
| Princess Irene Lock East | 1974 | 260 | 24.0 | 12 | 11,232 |
| Lek Canal (lifting height 1.80 meters) | |||||
| Princess Beatrix Lock 1 | 1938 | 225 | 18th | 18.30 | 7,290 |
| Princess Beatrix Lock 2 | 1938 | 225 | 18th | 13 | 7,290 |
| Princess Beatrix lock new | 2019 | 276 | 25th | 18th | 12,420 |
Source: (p. 30)
Entry from tributaries
The Amstel that the capital gave the Netherlands its name, does not flow after the construction of the NS-K more freely into the IJ, but is coming with the same level of the South to the NS-K above. On its partially canalised course ( Amstel-Drecht Canal ) through the Amstelland , it is also used to drain water from the adjacent land. It flows through the canals in Amsterdam and also refreshes the water in the canals . The customs house lock ( Tolhuissluis ) northwest of Nieuwveen forms the southern end of the Amstel .
A targeted flushing of the canals took place until 2010 through the use of the Zeeburg pumping station ( Gemaal Zeeburg ). It is located south of the Oranjeschleusen on the ARK and draws water from the Markermeer via a culvert ( Syphonsluis ) under this canal and diverts it into the Lozingskanaal and the parallel Nieuwevaart . By closing various lock gates in the canal system, the flushing water is distributed in the city canals of Amsterdam. Today, the pumping station for flushing is only operated at times when the oxygen content in the canals is too low.
The polders in the Amstelland are also drained via the many smaller rivers that originally flowed to the Zuiderzee. When the ARK was built, some of the rivers were 'cut' and now 'cross' the canal. These 'side arms' can be closed by sluices or gates, but are mostly open nowadays. These rivers are connected to each other and to the Amstel by canals. In this system, water movements occur mainly when it rains and through the pumping stations. South of Amsterdam, the Weespertrekvaart - the towing canal to Weesp - has been providing a connection between the Amstel in the west and the Vecht in the east since 1639 . At Driemond , this channel receives an inflow from the Gein and then crosses the ARC. On the east side, the continuation to the Vecht is called Smal Weesp . The part of the tow canal in front of the ARK uses the former Gaasp tributary , which flowed into the Zuiderzee together with the Diem and which today provides a further connection to the ARK near Diemen . The Gein , coming from the south, has a connection to the Angstel further up in Abcoude , which is connected to the Amstel near Amstelveen via the Abcoudermeer and the Holendrecht . To the north of Utrecht, the Nieuwe Wetering creates another water exchange between Angstel and the ARK.
The river Vecht , which flows north from Utrecht to the north, exhibits a remarkable phenomenon , as it flows in two directions: from Muiden am IJmeer to the south and from Utrecht to the north, to enter the canal at Nigtevecht . The total of five locks between the Vecht and the ARK have been open permanently since 1983, so that water is constantly exchanged. The former course of the Rhine ( Rijn ) also crosses the ARK south of Utrecht as the Leidse Rijn . To the west of Harmelen it continues to flow as Oude Rijn to Katwijk and into the North Sea. At the junction with the canal there is an important pumping station ( De Aanvoerder ) to supply the Amstelland with fresh water in times of need.
Water balance - discharge
In order to maintain the water level in the canal system, the 3 billion m³ of water discharged annually must be drained into the North Sea. Otherwise there is a risk of flooding and shipping would be hampered. In contrast to the past, since 1975 the drainage has only taken place in IJmuiden, so that the penetrating salt water can be returned as quickly as possible. The total amount corresponds to an annual average of around 95 m³ per second .
Water drainage in IJmuiden
During construction of the NS-K in the 19th century was right next to the Südschleuse in IJmuiden sluice of 10 meters wide built, but which could dissipate only at low tide water. If there was additional demand, one of the two locks had to be used, which was then not available for locks. During the renovation of the locks in the 1960s, this passage could be closed, as this task was fulfilled by the new and larger sewer on the north side.
In the 1940s, the transmission canal ( Spuikanaal ) was built between the north lock and the blast furnace port, which was intended for national defense in the form of inundation . The barrier structure was never used for this purpose and was converted into a sewerage structure. The sluice, which was put into operation in 1945, has seven openings 5.90 meters wide and 4.80 meters high, in order to be able to discharge up to 500 m³ of brackish water per second in free runoff into the North Sea at low tide. This also enabled the ship throughput to be increased at the locks, since no separate flushing processes had to be carried out via the locks. After the renovation of the sealing elements in the sewer in the 1990s, the discharge capacity could be increased to 900 m³ per second. (P. 296)
The prevailing wind from the west causes a water level at low tide that is often above the level of the canal. This means that adequate drainage of water via the sewer is not guaranteed. Therefore Rijkswaterstaat decided to build a pumping station next to the sewer , which went into operation in 1975 with four pumps (each 40 m³ / sec.). By 2004, two more pumps (50 m³ / sec.) Were added, so that today a maximum of 260 m³ per second is possible with a delivery head of 2.30 meters. This pumping station is the largest in the Netherlands.
Siel and pumping station have a total of four functions. In the context of water management, the most important is the removal of excess water. In addition, they ensure the water quality by flushing the sewer system. Due to the location of the structures on the North Sea, they also fulfill the important function of a flood barrier in the sense of the delta plan. Ultimately, they are responsible for dewatering in the canal in order to keep the level as stable as possible for shipping. The control center for monitoring these functions is located in IJmuiden. There the pumps and closures of the two local drainage systems and the inlet to the Oranjeschleusen are controlled by remote control.
Source: (pp. 277 to 280 and pp. 292 to 311)
Historic water drainage at the Orange Locks
At the eastern end of the NS-K, further drainage options were created during the construction of the IJ dam and the Oranjeschleusen. Until the construction of the final dike , tidal influence existed on the east side of the Oranjeschleusen until 1932, so that higher and lower water levels were compared to the North Sea Canal. A sewer ( Spuisluis ) was built to enable the excess water to run off naturally in the Zuiderzee at low tide . The passage that is still in operation today is 10 meters wide and is located right next to the south lock.
In order to be able to discharge the water in the Zuiderzee even at high tide, a pumping station was also built on the north side near Schellingwoude. The 'steam water mill ' ( Stoomwatermolen ), which went into operation in 1871 , had three separate passages 4.5 meters wide and 40 meters long, which could be closed by stem gates. An Appold pump from England was installed horizontally in each channel . These centrifugal pumps were driven by three steam engines powered by eight steam boilers. However, the system showed various structural defects and the steam engines did not achieve the planned output of 225 hp by far.
The problem of poor drainage was exacerbated by the Merwede Canal , opened in 1892 , because more water from drainage areas was fed into the canal system via this canal. Therefore, an increase in the discharge capacity was urgently required at this point. As a solution, a new pumping station was built, which went into operation in 1895 as a bucket wheel pumping station ( Schepradstoomgemaal ) south of the lock system . Next to a central boiler house there were three passages on the left and right, each of which had a bucket wheel 8.5 meters in diameter and three meters wide. The actual performance of the machine system was higher than calculated, so that four bucket wheels were sufficient in normal operation.
With the commissioning of the bucket wheel system, the old steam water mill could be taken out of operation and the boilers with the machines and the chimney were removed. It was not until 1998 that the structural part, apart from the still existing openings under the demolition hammer, was added. After the large sluice in IJmuiden was put into operation, the bucket wheel pump station was also shut down in order not to pollute the IJsselmeer with the brackish water from the canal. However, in order to increase the total discharge capacity, this pumping station had to be put into operation again in 1968 - albeit with diesel engines. After the pumping station was added in IJmuiden in 1975, the pumping station was finally decommissioned and was demolished in 1990. In the meantime, the three southern passages were used to let water into the inland IJ while the northern passages were closed.
Source: (pp. 280 to 292)
Water drainage to the Markermeer
If the water levels in the Amsterdam canal system are too high, the Zeeburg pumping station is also used. The horizontally installed pumps allow pumping in both directions. The current building dates from 1943 and was equipped with three pumps with an output of 800 m³ per minute each. In the 1960s a fourth pump was added that can deliver 1200 m³ per minute. The flow of a maximum of 60 cubic meters per second takes place under the ARK into the IJmeer as part of the Markermeer.
Water extraction for drinking water use
Due to the content of brackish water in the NS-K, there is no withdrawal for drinking water treatment in this area. In contrast, the ARK is of great importance for the drinking water supply in the regions of Utrecht, North Holland and South Holland. The fresh water introduced from the locks on the Lek is used for drinking water treatment. Waternet , a joint venture of the water association Hoogheemraadschap Amstel, Gooi en Vecht and the municipality of Amsterdam, operates together with the water supplier Provinciaal Waterleiding Bedrijf Noord-Holland (PWN) a canal water extraction in Nieuwegein on the west bank of the Lek Canal. Because of the content of heavy metals, salts, pesticides and other pollutants, the withdrawn Rhine water has to be subjected to extensive pretreatment by precipitation and sand filtration . The cleaned water is then pumped over 55 kilometers to the dunes of the Amsterdam water supply ( Amsterdamse Waterleidingduinen ) south of Zandvoort . In use since 1853, it is the oldest water catchment area in the Netherlands. Every year 50 million m³ of raw water are extracted here and processed into drinking water for the city of Amsterdam in the Leiduin waterworks.
The aqueduct to Zandvoort will continue to IJmuiden and there under the NS-K through the dunes of the North Holland dune reserve , where the utility PWN also enriches the groundwater. The raw water obtained from this is processed into drinking water and distributed in the province of North Holland and on the island of Texel. In addition, the Tata Steel plant - formerly Hoogovens - in IJmuiden and a paper mill in Velsen also draw water from this line for their service water supply.
Brackish water problem
The lock processes in IJmuiden are responsible for the permanent penetration of salt water from the North Sea into the North Sea Canal. Mixing it with the fresh water in the canal creates brackish water that cannot be used for any further use, because the permanent salinization damages nature, agriculture and horticulture in the vicinity. The higher water level in the canal causes brackish water to drain into the groundwater in the surrounding land.
Salinisation through the IJmuiden locks
Due to the canal water level of NAP -0.40 meters, the water level is below the level of the North Sea for most of the time, so that the salty excess water from the locks enters the canal. Even with the same water level in the North Sea and NS-K, when the lock gates are opened, more salt water penetrates into the lock chamber or into the canal, because the salt water with its greater density immediately pushes itself under the fresh water like a tongue. As a result, the brackish water zone in the canal penetrates further and further east and threatens to flood the canal system of the city of Amsterdam. A certain back pressure is created by the discharge of water from the land drainage along the North Sea Canal and the through-channel at the IJ dam. However, this fresh water tends to stay on the surface. All excess water has to flow into the North Sea, for which the separate Spuikanaal with sluice and pumping station was created in IJmuiden.
The problem of salinisation of the canal water is given a new dimension with the construction of the new sea lock . If one were to only consider the 20 centimeter overhang from the lock - without taking into account the density flow - around 10,000 m³ of North Sea water would enter the canal. The salt input corresponds to about 40 truckloads of salt with each lock. In order to counteract the increased salinization, Rijkswaterstaat started the project of selective return for water management in the North Sea Canal . For this purpose, a concrete wall is to be drawn in in the Spuikanaal , with an opening 4 meters high and 70 meters wide at the bottom. Due to the higher density of the salt water, the brackish water flows increasingly through this opening while retaining the fresh water above and as much salt water as possible can be fed to the sluice and the pumping station. Construction is scheduled to start in 2020 and should be completed after two years.
Salinisation at the Orange Locks
With the construction of the dike , the Zuiderzee became the freshwater lake IJsselmeer without the influence of tides. The two sluice structures Stevinsluizen and Lorentzsluizen keep a constant water level of NAP -0.20 meters (summer) in the IJsselmeer. As the largest freshwater reservoir in the Netherlands, the IJssel and Markermeer must be protected from salinisation by the brackish water in the NS-K. Therefore, the pumping station at the Oranjeschleusen was stopped with the construction of the sewer in IJmuiden. Fresh water is fed into the NS-K through the existing flushing channel in the IJ dam in order to reduce the penetration of brackish water.
Soil salinization in the green heart
The area between the cities of Amsterdam, Utrecht , Rotterdam and Leiden is known as the "Green Heart" ( Groene Hart ) of the Netherlands. It is an agricultural area with many greenhouses that have a high demand for water. The large number of bodies of water are used to irrigate the land, with the partly canalised Hollandse IJssel playing a central role.
Due to the location of the polders and lakes below sea level, salt water pushes in from the underground. However, the salt content in the agricultural areas must not exceed the concentration of 300 mg / l, as this would damage the cultivated plants. Usually, rainwater runoff causes this salt to "naturally" leach out. But in periods of drought this flushing effect is missing and water from the 'flowing wave' has to be used for B. the Hollandse IJssel can be helped. If there is no precipitation for a long time in the catchment area of the Rhine and the discharge in the Rhine falls below 1,100 m³ per second, the fresh water supply in the "Green Heart" can no longer be secured. Due to the low back pressure of the Rhine water, the salt water from the North Sea can advance inland via the Nieuwe Waterweg , so that the salt concentration in the Hollandsen IJssel exceeds 300 mg / l. For comparison: sea water has a salt concentration of 25,000 mg / l.
In this case, the four Waterschapen on the canal system have made agreements with each other on the so-called "climate- resistant water supply" ( Klimaatbestendige Wateraanvoervoorziening ), which provide for three routes to fresh water supply. Via the Noordergemaal in Utrecht, water can be channeled from the ARK via the Merwedekanal and the 'Doorslag' near Nieuwegein into the Hollandse IJssel. A second route leads via the "De Aanvoerder" pumping station in Utrecht, which was specially built for this purpose and can pump seven m³ per second from the ARK into the Leidsche Rijn and on to the Oude Rijn . To do this, however, the connection between the canal and the Rijn must be closed so that the pumped water does not flow back immediately. As a result, shipping on the Rijn has to be stopped.
The third option is via the Zeeburg pumping station in Amsterdam, which was actually built for drainage, but is also used to flush the canals. In this case, by shutting off lock gates in the canal system, the water is directed to the Amstel, which is 'forced' to flow backwards. As a result, fresh water reaches the upper end of the Amstel on the Tolhuissluis . During this time, shipping traffic within the canals is severely restricted. So far, this special fresh water supply had to be put into operation twice (2003 and 2010) in order to pump water into the "Green Heart". In 2003 there was no shipping traffic on the Leidse Rijn for two months.
Intelligent water management
The water drainage situation in IJmuiden is of central importance for the water balance in the entire region of the canal system of NS-K and ARK. If more water gets into the canals during precipitation than can be discharged from IJmuiden into the sea (maximum 260 m³ / s), the water level rises. Against the background of the threatened salinisation of the polders, the goal today is to keep the fresh water in the system for as long as possible and not to discharge it into IJmuiden 'unused'. To this end, the water boards involved have decided to work more closely together in order to be able to manage the water balance in the entire region more efficiently.
For an "intelligent water management" different scenarios for floods and drought were worked out and mapped in model calculations. Together with all current information on the high or low water situation and the status of the pumping stations of all waterschapen, the individual water managers in operational water management can keep an eye on the entire system and make optimal use of the buffer space in the system. Only when the water levels in the system continue to rise are the additional drainage options used via the pumping stations in Katwijk (94 m³ / s), Den Helder (60 m³ / s) or Amsterdam-Zeeburg (60 m³ / s). This means that fresh water is available for various uses for longer and longer, and damage due to lack of water or flooding can be limited.
Pumping stations for rinsing and drainage
| Surname | place | Output [m³ / sec.] |
introduction | Coordinates |
|---|---|---|---|---|
| Flushing pumping stations for fresh water supply | ||||
| Gemaal Zeeburg (pumps in both directions possible) |
Amsterdam | 60.0 | <- Lozingskanaal Markermeer -> |
52,367 ° N 4,953 ° E |
| Noordergemaal | Utrecht | 18.0 | Merwedekanal | 52,051 ° N 5,106 ° E |
| Picture De Aanvoerder | Utrecht | 5.3 | Leidsche Rijn | 52,083 ° N 5,078 ° E |
| Relief pumping stations | ||||
| Rijksgemaal | IJmuiden | 260.0 | North Sea | 52,471 ° N 4,602 ° E |
| Painting De Helsdeur | The hero | 60.0 | North Sea | 52,946 ° N 4,788 ° E |
| Gemaal Koning Willem Alexander | Katwijk | 64.0 | North Sea | 52,208 ° N 4,406 ° E |
Further use of canal water
The power plants in Utrecht, Amsterdam and Velsen take cooling water from the canals, but it must not be too warm when it is returned. This would endanger the fish population.
Both canals serve as a fishing ground for many professional fishermen and are popular fishing spots for sport anglers as they form one of the most important routes for fish migration in the Netherlands. As a special feature, the transition from fresh to salt water in the canal takes place gradually so that the fish can adapt to the changing salt content. However, the fish are hindered by dams, sluices and pumping stations in order to get into the canal system alternately from the North Sea or from the Markermeer. Noise and eddies caused by the ship's propellers keep the fish from swimming through the locks. And high flow velocities in the passage channels also form a barrier to fish migration. In order to remedy this situation, Rijkswaterstaat has generally decided to allow the passage of dams for fish.
In IJmuiden, the southern passage in the sluice was designed as a fish passage for this purpose. By reducing the speed of the pumps, the fish can also pass the pumping station more easily. In addition, the Kleine Sluis was made usable for fish passage in 2017. Closable openings in the lock gates can be automatically regulated depending on the tide so that migratory fish can easily swim through.
At the IJ dam, the middle of the three culverts on the former steam water mill (north side) was converted into a three meter wide fish passage as early as 1975. A second fish passage was created at the former Schepradstoomgemaal, where one of the six culverts is used. [1] (p. 311)
Rijkswaterstaat and the adjoining Waterschapen try to make the canal banks close to nature in order to preserve the unique community that is bound to brackish water. To the west of the ferry from Buitenhuizen, near-natural riparian zones were created on both sides of the canal: the nature reserves Spaarnwoude and Buitenhuizen. In addition, the swallow wall and the kingfisher wall were restored in cooperation with the Zaanstreek bird protection station. Both bird species immediately discovered the new walls in 2016 and raised their young there.
Web links
- Facts about water in the Netherlands on rijkswaterstaat.nl (Dutch)
- Water levels at waters in the Netherlands on rijkswaterstaat.nl (Dutch)
- Fresh water for the western Netherlands on De Stichtse Rijnlanden (Dutch)
- Map and dates of the pumping stations in the Netherlands on gemalen.nl (Dutch)
Individual evidence
- ↑ Description of the North Sea Canal on: Rijkswaterstaat.nl (Dutch)
- ↑ a b c d e f G.J. Arends (2001): Locks and pumping stations on the North Sea Canal on publicaties.minienm.nl (Dutch)
- ↑ Key figures for the IY on rijkswaterstaat.nl (Dutch)
- ↑ Key figures for the Amsterdam-Rhine Canal at rijkswaterstaat.nl (Dutch)
- ↑ The Lek Canal on rijkswaterstaat.nl (Dutch)
- ↑ The pumping stations of the Waterschapen at: gemaalen.nl (Dutch)
- ↑ Amsterdam cleans the canals every night : medienwerkstatt-online.de
- ↑ a b The Zeeburg pumping station. watershap Amstel gooi en vecht, accessed on December 25, 2019 (Dutch, original title of the page: Gemaal Zeeburg).
- ↑ Lock at Nigtevecht
- ↑ Study on fish migration in IJmuiden on publicaties.minienm.nl (Dutch)
- ↑ IJmuiden pumping station at: gemaalen.nl (Dutch)
- ↑ Where does our drinking water come from: waternet.nl (Dutch)
- ↑ Selective return of brackish water to: rijkswaterstaat.nl (Dutch)
- ^ Johan Van Veen (1956): The salinization of the Dutch marshes and their control In: The coast 5, double issue. Heide, Holstein: Boyens. Pp. 73-86
- ↑ Waterschapen start water supply on waterforum.net (Dutch)
- ↑ The Amstel flows backwards on faz.net
- ↑ Water management at the ARK and NS-K
- ↑ Annual report 2016 Rijkswaterstaat (Dutch)