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Discharge measurement at the river "Große Roeder" in Saxony - Germany

Due to the seasonally strong weed growth and low flow during low water periods the measurement of water level and flow at the measurement site "Kleinraschuetz“ was rather distorted. It had to be corrected by putting in additional manpower for manual measurements.

Therefore it was decided to modernize the station completely and to install a stationary discharge measuring system. The challenge of the measurement situation was to find a solution that measures reliably at all water levels  from a low level of 29 cm to highest level with flood events at 310 cm.

 Read a detailed project description here

Fixed installation of water flow sensor

OTT SLD - Side Looking Doppler Sensor

Water flow meter for longterm data collection of velocity and discharge measurements

The OTT SLD uses acoustic Doppler technology for continuous measurement of water velocity and level in streams, rivers, and canals.

  • Fixed installation
  • Acoustic
  • Flow velocity
  • Side-Looking-Doppler for continuous discharge measurement in rivers and open channels. Discharge calculation based on velocity - index - method. Integrated vessel filter algorithm, Modbus interface and output of total volume of flow (max. interval 1 day).
  • ± 10 m/s
  • ± 1 % of measured value ± 0.5 cm/s
  • Measurement task: online measurement of velocity of flow and subsequent calculation of discharge per velocity – index method in water levels from 29 cm to 310 cm
  • Storage and management of all data for the Saxonian authority for environment, agriculture and geology (LfULG) with remote data transfer and remote maintenance of the measuring systems 

This was achieved by:

  • OTT SonicFlow travel time system (one-level cross path)
  • OTT SLD 2.0 MHz Side-Looking-Doppler-Sensor for measurement of local velocity of flow (index velocity)
  • OTT SE 200 shaft encoder water level sensor
  • Datalogger OTT LogoSens2 for monitoring and storing measured data, for discharge calculation and for  remote data transfer

The measurement profile was designed as double-trapeze and paved with stone. Two independently installed empty conduits DN 50 which are protected by a galvanized steel tube at the river bed (mainly during the pavement works) cross the water body. For easier access to the cables a cable duct has been installed.

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