Discharge - ADCP (SonTek RiverSurveyor)

Parameter to be measured:

Discharge, flow velocity, depth

Method:

Acoustic Doppler Current Profiling

Equipment:

• sensor (M9)
• processing unit (data processing, storage, GPS receiver, communication)
• GPS antenna
• platform (raft)

Advantages:

• high resolution velocity profile of river transect (up to 128 cells)
• dual frequency sensor covers wide range of depths (0.3 - 40 m)
• position can be estimated via both bottom tracking and GPS
• intuitive software for both PC and Windows Mobile
• measurement continues even when connection is lost
• configurable options (communication: BT/radio, GPS: GPS/GNSS, platform: low /high velocity/remote controled)

Disadvantages:

• platform is quite bulky
• price

What to watch out for:

• transversal speed must be lower than flow velocity
• deeply incised riverbeds and vegetation may strongly impair GPS reception
• The product basic GPS-setting is advertised as "dGPS", but is merely ordinary SBAS-corrected GPS. True dGPS-solutions (base - rover) do exist, but post processing is not supported. Other GNSS-receivers may be customized with extra hardware.
• Stratification of temperature and salinity affects the depth measurement. This can be corrected for when a CastAway CTS sensor is used. Import of data otherwise acquired is not supported.
• The built-in temperature sensor shows strong thermal inertia, ie reacts slowly. In our test, an initial temperature difference of only 4 K (10°C to 6°C) took ~1 hour to equilibrate. The endpoint temperature was still 2 K above conventional measurements.
• When the sensor is not properly connected to the PCA, the latter appears fully operational, but does not connect via radio.

Problems/Questions:

• How does sediment concentration affect the measurements?

Price:

35000 € with basic GPS option and Hydroboard (2013, Germany)

Links

Projects that used the above equipment:

Other related web sites: