Water level measurement
The settings for the water level measurement are defined under Level (W) and Tech. level (W).
ATTENTION Do not start the RQ-30 while the target surface is within the blanking distance of the level sensor! Otherwise the RQ-30 will not receive level measurements for several minutes! See Specifications for the blanking distance of your sensor.
WMA, maximum level
The maximum expected water level (see Figure 17). It represents the upper limit of the W-v relation and is required for W-v learning.
WLL, low level border
The water level below which velocity measurements are not feasible (see Figure 17). It represents the lower limit of the W-v relation. A guidance value is 5 cm above the river bed or any protruding stones in the measurement area.
ATTENTION Below the low level border no velocity measurement is performed any more.
WCF, cease to flow level
The water level at which the flow velocity is always zero (see Figure 17).
Figure 17 Designation of water levels
In general, the predefined water levels respect the rule: W_Q, Q-30 > WMA > WLL > WCF
Adjustment
The most important setting for water level and discharge measurements is the level adjustment. It is essential that the measured water level W is referenced to the levels in the cross-Sectional profile and the discharge table
The procedure to adjust the level is different for sites with and without existing water level measurements.
Adjustment with known water level
The adjustment with an existing water level measurement is simple as the actual water level is known. However, it is essential that the gauge zero GZ of the existing water level measurement is defined as the reference level for the discharge table.
The water level measurement of the RQ-30 sensor is set to the known value by the following steps:
- Click the button Adjustment in the parameters list. This initiates a water level measurement and the measured level is displayed.
-
Enter the water level of the existing measurement. After confirmation the water level measurement of the RQ-30 sensor is adjusted to the given value and the entry for the mounting height W_Q is updated.
Figure 18 Water level adjustment with known water level
Adjustment with unknown water level
If the water level at the measurement site is not known, the mounting height of the RQ-30 sensor W_Q can be set directly. To do this, the exact vertical position of the RQ-30 sensor in the reference coordinate system must be determined.
Figure 19 Water level adjustment by setting of the mounting level W_Q of the RQ-30
Setting of the special water levels
The velocity measurement might be obstructed at low water levels. If the level drops below WLL, the velocity measurement is stopped to avoid erroneous measurements. However, the water level measurement is still performed and the discharge is determined by interpolating the velocity between WLL and WCF. The velocity at WLL is calculated from the W-v relation.