Non-contact discharge measurement with radar sensor RQ-30

Task

The Hydrographic Service of the federal state of Vorarlberg (Austria) is in charge of the discharge measurement at the river Rhine. The amount of water (water level, discharge rate) has to be recorded continuously. Especially during extreme situations caused by floods the exact determination of the discharge is important. A secure installation of the sensors where they cannot be harmed by debris or driftwood is required as to prevent damage or breakdown of the sensors. The possibility for easy and cost efficient installation as well as start-up are further important requirements to the measuring system.

Solution

The discharge radar sensor RQ-30 measures the velocity and the water level of the Rhine - contact-free and therefore maintenance-free and automatically calculates the current discharge in m³/s. The system is installed above the Rhine on the bottom side of the main bridge in the village Hoechst, where it is safe from high water and flooding. The RQ-30 is simple to install and represents a robust, reliable measuring instrument for discharge measurement. Therefore accurate discharge data is available even from extreme events like for example from the last hundred-year flood in August 2005.

Implementation

The current discharge rate is available right after the start-up of the operation. There is no time-consuming measuring campaign needed to get a rating curve. By continuously gathering the values of velocity and water level and calculating the discharge at the measuring site, the relations water level to discharge (h/Q) and velocity to water level (v/h) are available for analysis. Additionally, changes in the river bed can be recognised as they can be deduced from a shift of these relations. The discharge rate can then be amended accordingly. Hence, an exact quantification of the discharge rate is possible by continuously monitoring the flow velocity.

Further impressions