Components of Work When Conducting Depth Map Survey

Accordingly, Circular 49 stipulates that the components of the topographic survey using single-beam echo sounders with RTK positioning method are similar to the work using single-beam echo sounders with the DGPS positioning method, with some modifications as follows:

- The static station is set at the control point for coordinates and elevation. The distance from the static station (Base) to the roaming station (Rover) must be based on the accuracy requirements for depth specified in Appendix 4 and must not exceed 20 km;- Check the water level elevation of the water level observation station with the elevation of the water level using the RTK measurement method at the beginning and end of the measurement at a location adjacent to the water level observation station;- Check the elevation of the RTK positioning device as follows:- Arrange 3 benchmark points no more than 5 km apart, with elevation connection between the benchmarks transferred using Class IV leveling;- Position the static station at one of the three benchmarks, set the parameters, and transmit the signal; elevation value calculated to the millimeter;- Sequentially place the roaming station at the remaining 2 benchmarks, measure, and compare the measured elevation from the roaming station with the original elevation. The elevation error between these two measurement methods must be within the range ≤ 50 x mm (L is the length between the two benchmarks for testing measured in km).

For more details, see Circular 49/2017/TT-BGTVT, effective from February 15, 2018.

-Thao Uyen-

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