Remote Boat Water Depth Calibration - July 3

Current Opened Gates: Fully opened except gates # 23 and #24

All gates were fully opened in the morning and PLC screen showed 1.5 ft water depth at 8:20 am.  Large sand bars were appeared on the upstream pool 
as shown in Figure 2. To comprise enough water depth for the remote boat controlling, east gates were raised. Water depth was increased up to 3.0 ft. 
Water depth (distance between water surface and channel bottom) was measured with the echo sounder front of the intake structure 
(green lines in Figures 1 and 3). These values were compared with water depth surveyed with the scaled rod at center of the intake structure.
 
Three scenarios (no GPS, GPS without offset, and GPS with offset) were test for echo sounder calibration.  Linked plots show the channel bed shape along the line.
Flat channel bed shows the concrete lining bottom front of the intake structure (red line in the plots). 
In both scenarios of the no GPS and without offset, the echo sounder measured values were 0.19 ft and 0.21 ft shorter than the scaled rod surveyments, respectively. 
After 7 cm offset setting of the Sonarlite, the echo sounder measured 0.07 ft higher than the scaled rod surveyment.  Detailed information is in the linked plots.
Additional calibrations with different offset and GPS NMEA rate setting are needed.
  Click for surveyed channel bed level
 Figure 1
 

   Figure 2
 
 
 Figure 3 Figure 4