Measuring the effects of groyne reduction in a major Dutch river
To gain accurate insight in the discharge of the Amsterdam-Rhine canal, one of the most used canals for shipping and transportation in the world. The discharge data should help to define and understand the water regime in the canal and improve management of this water resource.
TD-Diver dataloggers in combination with horizontal acoustic doppler profilers, HADCP, were deployed to measure water levels and discharge at the Prince Bernhard lock of the Amsterdam-Rhine canal at Tiel, in the Netherlands.
Water levels of the Amsterdam-Rhine canal at the Prince Bernhard lock are accurately measured by Diver dataloggers. This data, together with the discharge data gained by the HADCP, provides successful quantification of the water management of the canal.
Amsterdam-Rhine canal: an important water link in the Netherlands
The Amsterdam-Rhine canal is one of the most important transport links in the Netherlands connecting the port of Amsterdam with the industrialized Ruhr district in Germany. In the Netherlands, the Amsterdam-Rhine canal connects the river IJ and the river Waal. The 72 km long canal follows in a southeasterly direction from Amsterdam as it runs through the city of Utrecht, towards Wijk bij Duurstede, where it intersects the Lek branch of the Rhine and then continues to the river Waal, near the city of Tiel.
Besides being an important transport connection, the water of the Amsterdam-Rhine canal is also used by adjacent water boards for water level regulations in surrounding polders. Important considerations for regulation of these water levels are minimizing flooding and managing the available water resources between the different stakeholders, so it is vital to get a better understanding of the discharge of the canal. However, getting reliable information on the discharge under low current velocity is challenging. Boats’ movements and the functioning of locks contribute to frequent current fluctuations and have an impact on discharge measurements as well.
Under low discharge condition of the Rhine, the Amsterdam-Rhine canal has an important role in the water supply of the West Netherlands. Water in the canal is a source for managing the polders and controlling salinization. In time of water scarcity, there is a water distribution issue. Reliable information about the quantities of available water is essential.
In October 2017, Rijkswaterstaat, part of the Dutch Ministry of Infrastructure and Water Management, started a pilot project to determine the discharge at the Prince Bernhard lock. This lock is near Tiel and connects the Amsterdam-Rhine canal and the river Waal for ship navigation. Discharge data from this pilot project is part of the “Flow measurements under all conditions” research project.
Course of the Amsterdam-Rhine canal (image copyright: Centraal Bureau voor de Statistiek)
Discharge measurements with acoustic Doppler profiles and Diver dataloggers
To calibrate the discharge measurements, Van Essen Instruments installed surface water monitoring points and equipped these points with Diver dataloggers to measure the water level. Two TD-Divers were installed in the docks; one in the eastern and another one in the western dock. One TD-Diver was installed north of dock in the Amsterdam-Rhine canal. The TD-Divers were programmed with a sample interval of 1 second. These samples were averaged and stored every 10 seconds to minimize the influence of waves caused by ships and wind.
Locations of the TD-Divers in and near the Prince Bernhard lock.
During a 4-week period, the HADCP’s and Diver dataloggers collected flow and water level data. During this period, the Diver data was collected twice and validated. Validation steps included: Diver check, collection of the atmospheric pressure data for the Diver location, compensation and referencing of Diver data to water levels, structural correction of water column, and assigning quality codes to recorded water levels.
Recordings gathered by Diver dataloggers provided insight into accurate water level data at the eastern and the western side of the Prince Bernhard lock. Water level data at the north side of the lock were under an impact of the monitoring location site (monitoring point attached to a floating construction).
Prince Bernhard lock (source: https://beeldbank.rws.nl, Rijkswaterstaat / Paul Kok)
Discharge data recorded by HADCP is investigated by Rijkswaterstaat. Information on water level data, supported by water discharge information, will be used in the project “Flow measurements under all conditions”. This information will be crucial in the analysis of the water resource quantities in the Amsterdam-Rhine canal and its distribution to adjacent waterboards and end users.
Water levels in the eastern and western lock with respect to Normaal Amsterdams Peil (NAP – mean sea level). Note: the large changes in the water level are due to ships passing through the locks.