Zitierlink des Filmsegments
Rivers are dynamic systems, undergoing constant change. Varying flow velocities of the water result in sand and gravel being carried away or deposited. Low water run-offs in particular can have negative consequences for shipping. Sandbanks can build up, for example, and move downstream. The danger then is that ships can come in contact with the river bed or even run aground. Hydraulic engineering can prevent this and improve the river system. But what are the right methods to employ? The shape and length of groynes can be altered, for example. But before the responsible water and shipping authorities decide what
to do they consult the BAW, the Federal Waterways Engineering and Research Institute. The BAW is the central technical and scientific agency of the German Federal Waterways and Shipping Administration. The BAW uses highly developed modelling and measuring techniques, for both wide-ranging commissioned projects and scientific research. Physical models can reveal facts which are not visible in nature. They use clear water, so that changes in the river bed can be observed. Specialised analysing techniques make the processes involved visible. The models are based on studies of actual conditions in nature. For examining natural phenomena, the model analogies must be as close to nature as possible. The findings of model studies are used in many cases - often for many years. They are linked with numerical methods -with computer simulations, in other words.
Numerical models simulate and display reaches in the river that are critical for shipping. Physical models also examine the effects that measures have on the flow of floodwater, for example, or on the ecology of a site. Before water is
fed into this model, the reference points for the optical measuring system are uncovered. Systematic examinations of the flow at and around groynes can be conducted on a simplified half-river model with a solid bed. The 27-metre length of the model represents around 800 metres of actual river. Once everything is ready, the water can be let in. The depth of the water is regulated by a weir. If physical model analogies are complied with, the behaviour of the flowing
water is similar to that in nature. White plastic discs, known as tracers, reveal the flow patterns. What's being examined here is the effect that groynes with cut-outs have on flow patterns in the groyne fields. Without cut-outs, the flow pattern is that of standard groynes. These tests, conducted in cooperation with the Federal Institute of Hydrology, aim to improve conditions for flora and fauna in groyne fields. The results will then be observed and analysed in nature. The level of the tracers and their speed in the flow are recorded optically by 3D Particle
Tracking Velocimetry - PTV for short. Three cameras with different
viewing angles record the white tracers. With the help of
reference points, their position, level and speed in the current can be calculated. The calculation produces this image of the flow in the groyne field. Red is the strongest current, blue the weakest. This model of the River Oder is 78 metres long, representing a 7.8-kilometre stretch of the actual river. It's a complex hydraulic model with a movable bed and using advanced test and measurement techniques that are largely automated. But some of the preparation still has to be
done by hand. No two
experiments involving movable beds run quite the same, so a
number of tests are made, which are then statistically evaluated. Here, the next experiment is being prepared. The two funnel-shaped
containers on the roof hold the water for the experiment. They're designed to supply water at a constant pressure, so its introduction into the model
can be precisely regulated. This model is examining various groyne geometries in order to improve conditions for navigation. Instead of
the sand and gravel of the river bed, very light polystyrene has been chosen. This
material behaves in the model just like sand in nature.
The figure is of roughly the same scale as the model: 1:40. Some phenomena are
visible without auxiliary means - like the eddies coming from the tips of the groynes. Counter currents occur in the
groyne fields, made visible here by adding dye. The measuring gantry can be manoeuvred to any point on the model.
Here, too, the recordings are made by three digital cameras.
Triangulation computations produce a three-dimensional picture of the river bed
resulting from the test. Special attention is focused on deformations of the bed. How does the bedload move in the river? Where do dunes or sandbanks occur and how do they shift through the river? The photogrammetric data are used to produce digital terrain models. The digital terrain model data are gathered every 10 seconds for over 11 hours. This is the equivalent in nature of a measurement every 14 hours for a period of 6 years. The BAW also examines hydraulic structures: the Obernau barrage dam on the River Main near Aschaffenburg consists of a 300- metre-long lock, a weir, a power station and a fish ladder. The structure dates from 1930 and is now showing its age. To make locking safer and faster, and to avoid waiting times, it's planned to construct a new lock next to the old one. The weir system
is also to be renovated. Before work can begin, the
planners need to know how the existing and the new structures will behave during floods
and how flood waters will
affect navigation. In addition, they want to find out how an inflatable weir 250 metres downstream from the existing weir system would perform. To test
all this, a solid-bed model is built on a scale of 1:40. We can see the new lock chamber next to the old one, and the new pillars of the weir. Water is fed into the model automatically to test how floodwater affects the lock system and what conditions will be like for shipping.
The 60-metre-long model represents a 2.4-kilometre-long stretch of the River Main. The effects of structures in water can be measured by various methods. Optical methods often
involve the use of tracers. The BAW has developed and
built this tracer dispensing machine. The staff have named it their "particle accelerator". It can
not only control the number of tracers dispensed but also precisely regulate how many are dispensed in a given time.
The tracers are recorded with a camera. So the flow behaviour at any point on the model can be analysed.
The 4 light points in the corners of the monitor serve as reference points for the calculations. The result is this analysis showing the distribution of flow velocities. But back to the question of how the new system will cope with floodwater. It takes some time for the water to fill up to the one-hundred-year flood level. Even the lock
control station itself is now under water. The computer charts
water levels at a control point and at the weir and compares them with the acceptable hundred-year-flood level. The water
levels are ascertained with the help of water gauges. The measuring vessels are connected with the model according to the principle of communicating pipes. The
measuring equipment uses ultrasound to measure the height of the water in the measuring vessel continuously. The data are archived
immediately for further analysis and quality assurance purposes. Like the
ultrasonic water level measurer, a lot of the equipment used is not commercially available and is developed and built in
the BAW's own electronics workshop. The various components of the
models are also designed and constructed at (the) BAW. On
the basis of the plans,
moulds are built, into which the concrete is poured and the reinforcing inserted. The model for the Obernau Retaining Dam is also made of this sort of concrete elements. Once
the preliminary studies are complete
and all questions have been answered, work on building the new system can go ahead. The plan for Obernau is to build an inflatable wear instead of a conventional one. It's still a little known sort of weir construction technique. The BAW has constructed a demonstration model. Recently the BAW has amassed quite some knowledge and experience of inflatable weirs. Three are already in operation
in German waterways. Electrically driven
valves open and close to fill and empty the weir.
The principle of communicating pipes is used for this. Clamping
rails hold the water-filled weir tube in place on the river bed and at both dam pillars. The water in the tube and the regulating chamber is emptied to release the dammed up water. To dam the river, the chamber and tube are filled with water again. The model of the new water saving lock in Minden, on a scale of 1:25. These locks are designed to reduce water consumption in canal systems. Before a ship heading downstream can enter the lock chamber, the water level has to equal that upstream. The old and new
locks at Minden link the Mittelland Canal and the River Weser. Most of the water
for filling the lock comes from the water-saving basins to the side - the rest from the upper canal level.
Black dye is added to show the course of the water. Filling and emptying the
lock are tested and optimised in the physical model and, of late, via numerical detail models. The aim is to
reduce the time required for filling and emptying the lock chamber by improving the number of culverts. The culverts link
the water-saving basins with the pressure chamber, which is situated below the lock chamber. The water is forced from the
pressure chamber via circular filling openings into the lock chamber.
The dye makes the water flow visible. What's aimed at is even distribution during filling.
The new lock at Minden is equipped with 3 water-saving basins to one side of the lock chamber. Basin 3 is built on top of basin 1, with number 2 next to them. The 3
basins save around 60 per cent of the water needed to fill the lock chamber. To ascertain the most efficient number of culverts from the water-saving basin without rebuilding, the basins were equipped with both one and two culverts. Various
situations can be tested safely with the model - such as the intensity of water hammers in the case of an operating error or an
emergency stop when the valves in the culverts are closed quickly. Dye is also used
to reveal the flow behaviour of the water leaving the lock chamber. This creates strong turbulence in the water of the lower canal.
This test examines various shapes of filling openings at a scale of
1:10. The formation of surface flushes and the intensity of the outflow are tested, to avoid problems later for ships and pleasure craft in the lock chamber. The flow behaviour
is again made visible using dye. All the processes in
the model are controlled by a computer, installed in a
measuring booth. It also stores all the data and immediately
displays the measurement results following a test. Valves control the
flow of water to and from the lock chamber and water-saving basins. Schedules for the
valves are worked out which take into account the maximum permissible forces exerted on ships and avoid negative effects such as abrupt surge waves. Emptying
the lock chamber and filling the water-saving basins to the left are shown here with 8-fold time-lapse. The filling and emptying system of the new lock at Minden shown in the model is based on the system used at the Uelzen II lock. The Uelzen
II design was also tested and optimised in a physical model form at the Federal Waterways Engineering and Research Institute in Karlsruhe.
|Alternativer Titel||Hydraulic Engineering|
Bernd Hentschel (wissenschaftliche Betreuung)
Udo Pfrommer (wissenschaftliche Betreuung)
Eberhard Grimm (wissenschaftliche Betreuung)
Kuno Lechner (Kamera)
Uwe Fanelli (Kamera)
Thomas Gerstenberg (Ton)
Andreas Grimm (Ton)
Abbas Yousefpour (Schnitt)
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|Herausgeber||Bundesanstalt für Wasserbau (BAW)|
|IWF-Filmdaten||Video-Clip; F, 16 min|
Die Bundesanstalt für Wasserbau (BAW) ist eine wissenschaftliche Beratungs- und Forschungseinrichtung der Wasser- und Schifffahrtsverwaltung (WSV) und ist im Bundesverkehrsministerium (BMVBS) angesiedelt. Sie arbeitet und forscht mit hochentwickelten Modell- und Messtechniken. In einem Modell der Elbe bei Schönberg untersucht man die Strömung an Buhnen und in den Buhnenfeldern. Die 3-D-Partikel-Tracking-Velocimetrie (PTV) erfasst Geschwindigkeiten und die Lage der Wasseroberfläche. Im Modell der Oder bei Hohenwutzen werden unterschiedliche Buhnengeometrien für eine Verbesserung der Schifffahrtsverhältnisse untersucht. Mit photogrammetrischen Vermessungen während des Versuchs entstehen dreidimensionale Bilder der auf der Flusssohle wandernden Sandbänke. Auch Bauwerke, wie Staustufen und Schleusen, werden im Modell untersucht. Das Modell der Staustufe Obernau am Main dient Untersuchungen, die die Auswirkungen baulicher Maßnahmen für die Schifffahrt bei Hochwasser erfassen. Aufbau und Funktionsweise eines Schlauchwehrs verdeutlicht ein Prinzipmodell. Sparschleusen in Kanälen reduzieren den Wasserverbrauch beim Schleusen. Die BAW optimiert auch die Funktionsweise der Sparschleuse Minden vor ihrem Bau im Modell.
The Federal Waterways Engineering and Research Institute (BAW) is the central technical and scientific governmental agency of the German Federal Waterways and Shipping Administration (WSV) which is part of the German Federal Ministry of Transport, Building and Urban Affairs (BMVBS). This institute works with and does research on highly developed modelling and measuring techniques. In a model of the Elbe River near Schönberg the BAW investigates current flows behind groynes and in groyne fields. 3D Particle Tracking Velocimetry (PTV) records velocities and the conditions of the water surface. In the model of the Oder River near Hohenwutzen different groyne geometries are examined for improving the navigation conditions. Photogrammetric measuring during the experiment creates 3D images of the dune movement on the riverbed. The BAW also examines structures such as barrages and locks in models. The model of the weir Obernau (on the Main River) shows the effects of structural measures on navigation during high water. A principle model illustrates the mode of operation of an inflatable weir. Recuperation locks into canals reduce the water consumption. The BAW optimizes the functionality of the recuperation lock Minden in a model before construction is begun.