Bathymetric Survey

I
The Survey vessel

• Bathymetric survey using a dual frequency echo sounder to identify the sea bed level and to identify muddy and sandy bed.
• Current measurements
• Water level measurements
• Wave measurements
• Sediment sampling

Survey Area
The survey area covers the entire length of the pilot area: from Somerset & Berks in the West (Region 2) to the mouth of the Mahaica River in the East (Region 4), including the Essequibo River up to Bartica. Survey lines were planned by dividing the area into 8 blocks as shown in the figure. The lines that stretch out from the coastline in block 1 to block 5 are bounded by the -7 m MSL which is approximately -5 m below CD (Chart Datum) which is extracted from the British Admiralty Chart (BA527). The spacing of the lines is 1 km.


Survey Area including survey lines.

Preparations
In October the survey vessel, arrived in Guyana and the (survey) equipment was installed. The dual-frequency echosounder (Midas Surveyor), Global Positioning System (GPS) and VHF were installed on the survey vessel, calibrated and tested. By the end of October the vessel was ready for launching. The vessel was christened Blygezight during a function that took place at Stabroek Stelling on 31 October. Subsequently, everybody was invited for a small cruise on Blygezight.


Cruise just after the launch.

Bathymetric Survey
Early November, the actual bathymetric survey commenced. Survey lines were sailed perpendicular to the coast. Each line was sailed up to approximately the 5m depth contour, up to 20km out at sea, while the echosounding equipment logged the bottom level.


Trainees survey-ing as part of the Training Programme.

Processing of data
Initial data processing and quality assurance is carried out at the end of each survey day. An example of the tide correction and processed data is given in the figure below that depicts the measured bathymetry.

See also Hypack site.


Tide correction.


Processed data.

Safety and Quality
The work is carried out using procedures for ensuring proper quality of the measurements and safety. Checklists are used ensuring that all required equipment is on board (and on land). Regular contact (radio, telephone, satellite) is established between the survey vessel and the base on land to ensure everything is ok and to monitor the position the survey vessel for safety reasons. As a further precaution the person in the Georgetown lighthouse keeps an eye on the survey or - in West Coast Essequibo - a fisherman is standing by and can sail to the survey boat in case of an emergency. Normally a skipper and two surveyors are on board, while at least one person stayed on land.