Bremen Weser Weir
The Weser weir in Bremen - Hastedt regulates the water level of the Middle Weser at Weser kilometer 362 . The Bremen Weser weir built in 1911 was replaced by a completely new one between 1989 and 1993, and it went into operation on June 10, 1993. It is located about 180 meters downstream from the old weir .
Old Weser weir
The aim of the Lower Weser correction by Ludwig Franzius was that the Lower Weser should clean itself of sediments by accelerating the tidal currents and thus a deep fairway should be available for shipping with little effort . The tidal limit moved upstream. This also extended the erosion of the river bed into the Central Weser . Bremen was obliged to put a stop to this development.
The Hanseatic city built its Weser weir 500 m downstream from the old Hemelinger harbor to set an artificial limit for the tides and at the same time to secure a minimum water level by means of a barrage for inland shipping . In addition, the previous expansion of the Outer Weser was intended to counteract the increased flow velocity and the increasing bottom floor erosion in the subsequent section of the Weser. It was one of several barrages that were built in the Weser over time. Today there are seven more weirs upstream.
Immanuel Kölle was responsible for the planning and construction management . The actual weir was built from 1906 to 1911, the pedestrian bridge over the weir in 1908. A fish ladder was built north of the dam. A brick building for the hydroelectric power station was built across the river. The turbines went into operation between 1915 and 1917 at different times. When the Reich took over the waterways , the Weser weir and the power station remained the property of the Free Hanseatic City of Bremen. In 1926 more turbines were put into operation. At the time, the hydropower plant covered around half of Bremen's electricity needs. To the south of it there were two locks: one 300 m long and 12 m wide for the then particularly economical tow trains and a short one for single ships.
During the Second World War the Weserwehr was damaged by bombs, but it was not until April 22nd, 1945 that the pioneers of the German Wehrmacht blew it up to make it unusable. The pedestrian walkway and most of the turbine system remained, however. During the ice disaster in Bremen on March 18, 1947, a drifting barge knocked over the pedestrian walkway. The weir was restored in 1948/49. But the building structure remained weakened and since November 1980 one of the weir bodies could no longer be moved, which contributed to the breakthrough of the Weser on March 15, 1981 . The state of Bremen then decided to completely replace the system.
The excavation pit is dammed with wooden boarding, the boarding is rammed with steam hammers
The sheet pile walls are rammed with steam rams on rails. You can see the wells of the groundwater lowering
The construction site seen from the wild pass (= fish pass)
The bottom of the waste floor in the underwater is protected by a concrete layer. You can see the pillars in the underwater and the first frame of the sector
Base fastening in the upper water, pillar partially finished
Erecting the upper needle weir blocks
Finished Weser weir, seen from the upper water. The pedestrian bridge leads over the Weser pillar to the river pillar, on the left the finished turbine house
Today's Weserwehr
The Weser weir consists of five fields, each 30 meters wide. The regulation of the water level above the weir takes place via the locks of the weir, five movable weir flaps , so-called fish belly flaps . The water level of the Mittelweser above the weir is at normal damming at NN +4.50 meters. Below the weir is the tidal part of the Central Weser. The height of fall at the barrage varies between about three and six meters, depending on the water level below the weir. The control of the storage flaps is fully automatic.
For the maintenance and servicing of the weir flaps, the individual fields of the weir in the upper and lower water can be closed with emergency seals and then pumped out.
In the weir threshold there is an inspection corridor that runs the entire length of the weir. A service bridge leads over the Weser weir, which can also be used by pedestrians and cyclists. The bridge is around five meters above the headwater. It connects to the service bridge over the locks so that passers-by can cross the entire barrage.
The weir is designed for a discharge rate of 3,400 m³ / s. This means that more water can flow off through the new weir than was the case with the old weir. This was only designed for a discharge rate of 2,300 m³ / s. Overall, the flood discharge concept at the Bremen barrage provides for a discharge rate of 4,200 m³ / s. The difference between the total runoff and the runoff over the weir is discharged via a lateral runoff area over the Werdersee and the Kleine Weser. During the floods in March 1981 , however, it became apparent that the lateral drainage area could no longer absorb the intended amount of water due to increasing construction. The water accumulated in the side room provided for the drainage and finally broke through the dike below the barrage and lock system. As a result, the flood discharge was re-regulated. The most expedient solution was to increase the capacity of the weir.
Next to the Weser weir there is a fish ladder on the island between the weir and the lock system . Another fish pass was created in connection with the Weser power station on the right bank of the river.
Construction progress
Because of the risk of flooding in winter, the main work could only be carried out in the summer months. The Weser weir was built in construction pits in several sections. Work began in 1989 on the left bank with the first excavation pit, in which the first field was built. Then in 1990 the next two fields were built in a second excavation pit. In 1991 the last two fields followed in a third construction pit. In parallel to the construction pits, measures were taken to secure the river bed. This was followed in 1992 by the installation of the locks and all of the equipment, as well as further floor protection measures. Trial operation of the new weir began in 1993. After the system went into operation in June 1993, the fish pass was built.
Cross-section through the building
View of the old Weser weir with sluice and the broken power station (in front) Downstream of the excavation for the new Weser weir, field 1, preparation for stabilizing the bottom of fields 2 and 3
The pillars of weir field 1 are partially in place, the excavation pit for weir fields 2 and 3 is in operation, weir field 1 is flown through
Old Weser weir and old lock in operation, power plant demolished, weir field 1 finished, weir fields 2 and 3 under construction, drainage through weir field 1 and later weir fields 5 and 6
Weir fields 1, 2 and 3 finished but not in operation, old weir still in full operation, drainage via weir fields 4 and 5 under construction through standing sheet piling
The new Weser weir is finished and fully operational, the old one has not yet been demolished, next to the left edge pillar (right) is the fish passage, the road bridge over the weir is ready,
Bremen Weser locks
The Weser locks were built from 1995 to 1999. They replace the old system that was in place until then, which no longer met the requirements and was severely damaged. In order not to interrupt ongoing operations, the large shipping lock was first built in the lower canal of the old small lock. Only then was the small ship lock built so that a lock chamber was always available for commercial shipping even during the construction period of the new lock system. The new plant was put into operation on June 30, 1999.
A service bridge leads over the lock system. Its clearance height, which is designed just under two meters higher above the large ship lock than above the small ship lock, is around ten meters in normal backwater in the upper water, and 7.5 meters in the highest backwater (NN +5.6 meters) (above the large ship lock) or 5.7 meters (above the small ship lock). The service bridge connects to the service bridge over the Weser weir and thus enables the entire barrage to be crossed.
Large and small ship locks have a common upper and lower channel for entry and exit. The entrance areas are separated by central stabilizers in order to avoid waves at the entrance and to separate the traffic in good time.
Large shipping lock
The upper gate of the lock consists of a rotating segment gate, the lower gate consists of a mitred gate . To protect the gates, there is a safety net at the upper gate inside the lock chamber; the gate can be protected by a rope towards the upper water. A corresponding shock protection in the form of a rope is also in front of the lower gate.
When the water level is low in the underwater, around 20,000 m³ of water are required for a lock , which is taken from the head of the Weser and returned at the lower head of the Weser. In the case of mountain sluices, the sluice is filled using a filling shell that is built into the head's rotating segment gate. To do this, the gate is lowered slightly and water can flow into the sluice via the filling shell. During the valley lock, emptying takes place via side gates on the lower head. In order to avoid damaging currents, so-called disruptive bodies are located below the sluice gates, which ensure the energy conversion of the incoming and outgoing water.
Dimensions
The chamber of the large shipping lock is 225 meters long and approximately 12.5 meters wide. This means that two inland vessels , each 110 meters in length, can be locked at the same time.
The jamb on the head is at NN ± 0.00 meters. With normal traffic jam (NN +4.50 meters) the water depth is 4.50 meters. The jamb on the lower head is at sea level of −6.00 meters. At mean low tide (MTnw) the water depth is about 4.60 meters.
Small ship lock
In addition to the large ship lock, the lock system also has a small ship lock. This lock is intended for small and sport shipping . It works automatically and is operated by the user himself. There are operating stations in the lock as well as in the lower and upper outer harbor.
As with the large shipping lock, the upper gate of the lock consists of a rotating segment gate, the lower gate consists of a striking gate. In the case of mountain locks, the lock is filled using a filler shell, as is the case with large shipping locks. During the valley lock, the lock chamber is emptied through protective openings in the impact gate. Disruptive bodies also ensure that no harmful currents occur in the small ship lock.
In the upper and lower water there is an exit via ramps so that boats can also be moved. This allows paddlers in particular to pass the facility quickly, as they can be transferred faster than through locks. Boat carts are kept available for transport on the lock area .
Dimensions
The entire lock system is 58 meters long. The chamber can be used over a length of 25 meters. The (usable) width of the chamber is 6.5 meters.
The lock chamber has an average height of 10.5 meters. The water depth at the upper head is 3.5 meters with normal damming, at the lower head there is still a water depth of about 2.6 meters with mean low tide water (MTnw).
building-costs
The construction of the new Weser weir and the lock system cost a total of 147.7 million euros.
Of these accounted for
- the weir system: 70.2 million euros
- the lock system: 69.9 million euros
- the fish pass: 3.2 million euros
- other measures: 4.4 million euros
The new building was financed by the Federal Ministry of Transport, Building and Urban Development (BMVBS). The weir system was partly financed by the Free Hanseatic City of Bremen .
Weser power plants
Old power plant (until 1987)
The old Weser weir had a hydroelectric power plant that was put into operation at the same time and operated by the then Stadtwerke Bremen . It lay between the actual weir, a small artificial island in the river, and the lock system. As a run-of-river power plant , it was equipped with eleven vertically arranged Francis turbines , had an installed capacity of eight megawatts and was designed for a flow rate of 301 m³ / s. It was switched off on May 4, 1987 at 12 noon.
New building (from 2008)
When planning the new Weser weir, considerations were also made about building a new hydropower plant; this idea was abandoned in 1999 by the then Stadtwerke Bremen, initially for economic reasons. The weir had already been designed for the integration of a hydropower plant with a so-called sixth weir field. 2001 saw the impetus for a solution under private law. In May 2008, after a planning period of over seven years, construction work began on a new power plant. Trial operation began with the inauguration on November 30, 2011, and has been running regularly since March 1, 2012. Unlike its predecessor, it is not located between the weir and the lock, but is designed as a diversion power plant .
literature
- Karl Löbe: Company Mittelweser. A plant for the future of Bremen. Published by the Weserbund eV, Verlag Hauschild, Bremen 1960.
- Hermann Harten: The barrage model Weserwehr near Bremen. In: Mittelungsblatt der Bundesanstalt für Wasserbau , No. 60, 1987, pp. 155–177 ( PDF file , 9.2 MB).
- Herbert Black Forest : The Great Bremen Lexicon . Volume 2: L-Z. 2nd, updated, revised and expanded edition. Edition Temmen, Bremen 2003, ISBN 3-86108-693-X .
Web links
- Page no longer available , search in web archives: Construction and operation of a hydropower plant on the Weser weir , Wasserkraftwerk Bremen GmbH (PDF file, approx. 1 MB)
- 25 years ago: The turbine power station on the Weser weir is shut down - electricity pays interest on construction costs , Kreiszeitung on the history of the hydropower station shut down in 1987
Individual evidence
- ↑ Karl Lobe: The Weser book, novel of a river . 1968, p. 125 .
- ^ Bremer Weserwehr ( Memento from November 17, 2015 in the Internet Archive ), Bremen Waterways and Shipping Office.
- ^ Fish passage barrage in Bremen ( Memento from November 20, 2015 in the Internet Archive ), Bremen Waterways and Shipping Authority.
Bremen |
Long tail |
Dörverden |
Drakenburg |
Landesbergen |
Shlisselburg |
Petershagen |
Hamelin
Coordinates: 53 ° 3 ′ 35 ″ N , 8 ° 51 ′ 52 ″ E