EasyQ
River Velocity and Stage Monitor
The EasyQ represents a new approach to river and channel flow measurements where multiple acoustic sensors are combined in a single instrument. First, the EasyQ is 3-cell current profiler that measures the velocity out in the middle of river, away from the direct influence of the banks. Second, the EasyQ is a high-precision acoustic stage sensor that meets the USGS specifications of 3-mm accuracy (1/100'). Third, the EasyQ is a four-beam echo sounder that allows you to observe changes in the channel bed or the vegetation growing in from the banks.
In standard applications, the EasyQ mounts on the sidewall with one acoustic beam pointing toward the surface (stage), two pointing perpendicular to the river flow (3-cell velocity) and the fourth beam pointing toward the bed. Data can be recorded at user-selectable rates and stored in the internal recorder or sent to a data logger using the SDI-12, RS-232 or RS-422 serial interface. The post processing normally includes a user-supplied model of the river (including the detailed cross section area) and the approximate velocity profiles (vertical and horizontal) before a final Q is derived for the river or channel flow. The method applied is usually referred to as the Index Velocity Method.
As with all Nortek products, the EasyQ comes with free Windows PC software that offers a simple and standardized method for setting up the sensor. It guides you through the process from configuration to data collection to data conversion, and displays numerical and graphical data online. The software also includes stage and range test modes for quick and simple installation assistance.
Velocity:
The EasyQ measures velocity in three adjacent cells with two horizontal Doppler beams looking sideways into the flow. You can adjust the position of the measurement cells to place them close to the sensor or further out in the river. The velocity is averaged over a programmable interval, ranging from one second to one hour. The carefully implemented Doppler processing gives you better than 1% measurement accuracy.
Stage:
Stage is measured with a vertical echo sounder that finds the strong echo off the water surface
with an uncertainty less than 3mm (0.01 ft). The measurements are assisted by the pressure sensor to reject out-of-range echoes from debris in the water. The measurement is insensitive to atmospheric pressure changes, and does not require vented tubes. Averaging over intervals of typically 1 second to 2 minutes filters out the effects of waves.
SDI12:
The EasyQ is hardware compatible with the SDI12 communications protocol, version 1.2. You will set up the instrument through the RS232 serial port using Nortek's standard software (for Windows 95, 98, NT or 2000), then tell it to switch to SDI12.
Flexibility:
There are many different ways for you to use the EasyQ. You can adjust sample volume and averaging intervals for your specific requirements. You can record data internally for fully autonomous measurements in remote sites or to back up your external data logger. The EasyQ's minimal power requirements and highly accurate data enable you to make measurements that are unobtainable with other sensors.
Custom transducer heads:
Do you have a special requirement for which the standard transducer head geometry will not work? We can produce custom head geometries specifically for your requirements, and we can do this cost-effectively!
Riverbed monitoring:
The standard transducer head comes with an extra beam, a bonus for the future. Beam 4 looks down at 45 degrees from vertical, and detects changes in the bottom associated with scour and siltation. The EasyQ includes diagnostic software that enable you to monitor changes in the river bed manually. We will implement improved automated monitoring in the future. When we do, these new capabilities will come to you for free via firmware download.
Key Applications
- Sites where stage alone is too limited to provide good estimates of river discharge
- Shallow and steep rivers with intensive precipitation and extreme flooding (flash flood)
- Rivers with varying bed conditions (bottom ice, vegetation, etc.)
- Ice covered rivers
- Sites where measurements during extreme situations can be problematic or dangerous
- River systems in need of continuous water balance calculations
- Irrigation and other pump-driven, man-made channels
- Installations where hiding the equipment is important (theft, vandalism)
Key functions
System:
- Acoustic frequency: 1 or 2 MHz
Velocity:
- Velocity range: ±10 m/s
- Accuracy: 1% of measured value ±0.5 cm/s
- Sampling rate: 1 s to several hours
- Maximum profiling range (typical): 10 m for 2 MHz and 20 m for 1 MHz unit
- Cell size: 0.2 to 4 m
Stage:
- Range: 0.15 to 10 m
- Accuracy/resolution: 3/1 mm
- Integration time: 1 to 120 s
- Diagnostics mode:
- Number of beams: 4
- Number of cells: 50
- Cell size: 20 cm
Sensors:
- Tilt (liquid level, max 20° tilt)
- Pressure (piezoresistive, resolution 1 mm)
- Temperature
Data communication:
- I/O: RS232, RS422, SDI12
- Baud rate: 300 to 115200
- User control: Handled via WIN32 software or ActiveX components
Data Recording:
- Capacity: 2 MB, extra 20 MB or 76MB recorders available
- Data record: velocity - 30 bytes + 6*Ncells, stage - 34 bytes, diagnostics - 234
Mechanical:
- Weight in air: 1.7 kg with alkaline batteries
- Weight in water: 0.7 kg buoyant
- Dimensions: 75 mm diameter, 590 mm length
- Materials: Plastic and titanium
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