AI supports flow measurements – May 23, 2022 – Christoph SOMMER and Johannes FRITSCHE – Environmental science news articles

SOMMER supports the city of Schärding, Austria, to improve flood management and warnings

The town of Schärding in Upper Austria has a long history of dealing with flooding from the Inn River. For the flood management, SOMMER has supplied a flow monitoring system that overcomes the challenging conditions of the river. By dividing the Inn into multiple cross-sections and monitoring each section with its own sensor, the inhomogeneous flow regime could be largely eliminated. A modular monitoring station with AI-enabled flow sensors, mobile-assisted data logger, autonomous power supply and a dedicated cloud server provide a robust system for reliable flow monitoring and alarm management.

The 5,200 strong municipality of Schärding in Upper Austria on the border with Germany is known for its Baroque town center on the banks of the Inn River. Its history dates back to the eighth century and is characterized by the atmosphere of nature and repeated floods, flooded alleys and paralyzed trade.
Schärding’s historic buildings are only slightly above the river and a swelling inn still leads to frequent flooding. In the summer of 2021, that happened again with its heavy rainfall in the northern Alps.
Given its historic development, Schärding relies on reliable flood management to minimize loss and damage.

Monitoring the flow of the River Inn
Good flood management requires careful monitoring of the Inn River with reliable techniques – and that is the challenge. The river Inn, which rises in the high Alps, is 250 m wide at Schärding.
In general, stationary flow measurements with one sensor require stable flow conditions. This is met if the watercourse is straight in upstream and downstream directions at least five times the width of the river. The river inn does not offer a straight section, but flows in a large bend through Schärding.
If there is an additional water inflow, it takes up to ten times the river width for the river flow to reach stable conditions again. A Schärding the river Roth flows into the Inn with little chance of reaching stability.
These conditions – river bend and confluence – are challenging and require an appropriate solution.
Two bridges cross the Inn in the city center, and the smaller one, closer to the confluence, will be used to carry power monitoring equipment.

Multiple flow sections improve accuracy

SOMMER – a specialist in non-contact flow monitoring – has risen to the challenge with a sensor from its RQ sensor family.
A standard flow sensor such as the RQ-30 can be used as a stationary or mobile instrument to monitor water flows from both small and large rivers. However, sometimes a single sensor is not capable of correctly capturing the water flow. This is the case at Schärding where a wide river has a very inhomogeneous flow pattern.
For such applications, SOMMER has developed an improved flow sensor, the RQ-30d, a multi-sensor device with the features of the popular RQ-30. It combines a section-by-section approach with artificial intelligence (AI) to meet the most challenging flow conditions.
The basic principle is a primary-secondary concept where multiple secondary devices communicate with a primary device that controls the required measurement tasks. Each of the secondary devices monitors the water flow of a subsection of the river cross-section and the primary device calculates the total flow. In this way, an irregular flow pattern is broken up into multiple parts with less inhomogeneity.
In Schärding, SOMMER has installed a multisensor RQ-30d with a primary and a secondary unit to cover the total river width. This arrangement is a compromise between accuracy and cost, bearing in mind that a three or four unit arrangement would be advantageous.

AI Tames Tough Power Conditions

To alleviate the effects of difficult flow conditions, the sensors of the RQ family are equipped with various AI functions. They can handle currents at very low and very high water levels and eliminate the interference from wind that generates ripples unrelated to the actual water flow. This is especially crucial because at low water levels or with super slow currents the water surface can be influenced more by wind. In high flow conditions, the AI ​​is normally not used or needed due to the high quality of the SOMMER hydraulic model within the RQ family.
Monitoring architectures with AI-enabled RQ-30d devices provide a single point of access to all sensors and enable interfacing with any data acquisition system.

A tuned data flow for top reliability

After the challenges of monitoring the situation were resolved, an adequate data acquisition and management scheme and a reliable alert system had to be implemented.
Because there was no mains power available on the bridge that carried all the monitoring equipment, an autonomous solar energy supply with rechargeable batteries was chosen. The SOMMER RQ flow sensors have an advanced energy saving mode that is activated between measurements. In combination with a SOMMER MRL data logger, the power consumption of the entire control room in idle mode can be reduced to less than 1 mA, extending battery life and increasing reliability.
The SOMMER MRL data logger activates the measurements, collects level, speed and flow data and activates SMS and e-mail notifications if predefined limits are exceeded. In addition, the logger regularly sends the obtained data to the SOMMER data cloud, which sends alert messages to social media platforms such as Twitter or Telegram. The MRL data logger also collects and transmits images captured by a connected camera, visualizing the situation at the measurement site. For example, the local authorities are continuously informed and they have the tools at hand to inform the public in the event of an approaching flood.

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