January 2019
OTT SVR 100 installed under challenging conditions at the gauging station in Triftbach
The gap between urban and rural areas is widening all the time – the number of inhabitants per city is continually increasing. On the one hand, demographic change with the ageing of many urban regions is contributing to this, but at the same time more and more young people are moving to the city.
Urbanisation, i.e. the multiplication and expansion of cities in terms of number, area or inhabitants, presents ever greater challenges for people and nature. The overexploitation of nature does not go unpunished and causes – in combination with climate change – sometimes severe catastrophes with great damage.
Floods and high water have been among the worst urban natural disasters in Europe in recent years. They were caused by short‑term heavy rainfall events or long‑lasting precipitation and thaw. Waters overflowing their banks can cause millions in damage to settlements and infrastructure. This damage potential is constantly growing as a result of the development of meadows and floodplains and the conversion of cellars into usable space. Climatic changes are also often the cause of extreme events.
The city of Rosenheim was hit particularly hard at the beginning of June 2013 after a cool and, above all, very rainy spring. At the River Mangfall near Rosenheim, extreme high‑water discharges with record water levels since 1899 were observed after several days of widespread precipitation.
Built‑up areas in Kolbermoor and Rosenheim were flooded due to overloaded older dikes. More than 1,000 people had to be evacuated. Flooding cannot be completely avoided as it is a natural event. However, preventive measures can reduce potential flood damage.
Such preventive measures include professional maintenance of water bodies and constant, reliable recording of measurement data. The modernisation of the discharge measurement station at Bad Aibling Triftbach near Rosenheim is one such measure.
The measurement station at Bad Aibling Triftbach is part of the state measurement network operated by WWA Rosenheim on behalf of the Bavarian State Office for the Environment and has been in successful operation for some time. In 2018, the station was scheduled to be retrofitted with new equipment.
The measuring station serves flood protection, drought protection and general assessment purposes. The reason for installing the OTT SVR 100 was the backwater effect caused by the River Mangfall during flooding events. During such events, the existing rating curve delivers erroneous data.
Sensors using the ultrasonic Doppler principle are not suitable, as the station is located downstream of a power plant where high oxygen levels repeatedly occur.
The Triftbach measuring station is equipped with:
The following infrastructure is planned:
Additional acquisition:
At the Triftbach measurement station, the existing water‑level measurement is complemented by discharge measurement. Discharge is determined by measuring surface velocity using the OTT SVR 100 Surface Velocity Radar. In parallel, an OTT RLS radar level sensor determines water level via radar measurement.
Both sensors transmit measurement data to the OTT netDL 1000 datalogger, which computes discharge using the two measured variables. Discharge is stored as a separate channel and is available like a measured sensor value.
Using PRODIS software, the flow calculation can be calibrated by comparative measurements at different water levels and discharges. Until such measurements are available, standard calibration models can be used.
The monitoring solution has a modular structure. Existing water‑level sensors and dataloggers can continue to be used and can be cost‑effectively supplemented with flow‑velocity measurement.
Non‑contact radar measurement of water level and velocity is particularly advantageous during flooding and in waters with high biological activity or high sediment loads. Since the sensors are not submerged, they are not clogged and require minimal maintenance. During floods, sensors are protected from damage caused by floating debris as they are mounted outside the water body.
In contrast to acoustic Doppler sensors, this solution operates reliably in very turbid water, with high sediment loads or high oxygen content and air bubbles, conditions that frequently occur during heavy rainfall and flood events.
The new OTT SVR 100 sensor enables safe and reliable discharge measurement even under challenging conditions. This allows gauging stations to function as discharge measurement stations where flow measurement was previously impossible or only achievable with great effort.
Thanks to uncomplicated integration into existing systems, existing gauging stations can be easily retrofitted. The OTT SVR 100 is therefore an important addition to the discharge‑measurement product portfolio and will contribute significantly to water monitoring and flood protection, especially in small and medium‑sized water bodies.
OTT SVR 100
OTT Prodis 2