Nusail Engineering Consultancy was contracted by Atkins to provide Hydrographic Survey, Geophysical (Sub-Bottom Profiling) Survey, and Ocean Current Investigation Survey services for the Khasab Port area Redevelopment site Investigation study in Khasab, Sultanate of Oman.

Ocean Current Investigation Study

Current measurements were conducted using the RDI Teledyne Current Profiler at four locations: two in Khasab Port (Stn. L1 and Stn. L2) and two in the proposed optional area, Khor Qada (Stn. L3 and Stn. L4). Measurements were taken at depths of 2 m, 4 m, 6 m, 8 m, 10 m, and 13 m, with data recorded at 2-minute intervals.

Geophysical Survey

A side scan sonar survey was carried out to identify key seabed formations, including coral, that might pose construction hazards or environmental concerns. Information about shipwrecks and outfall pipes was also included in the study area.

Results

Bathymetry Survey

An Odom Hydrotrac single frequency (200 kHz) single beam Echo Sounder was used to acquire bathymetry data. The 'bar check' results indicated a velocity of 1520 m/s for sound in water during data acquisition. The data were processed using HydroPro Software. The survey, conducted from April 19th to May 19th, resulted in a bathymetry chart at a 1:1000 scale. The survey area displayed irregular seabed features with relatively shallow conditions, particularly near the shore, in front of the creek, and inside the breakwater.

Current Measurements

• Stn L1: The current speed at the surface was generally higher than at the bottom. Current directions were mainly between 10° and 90° from mid-depth to the bottom, with scattered directions at the surface up to 4 m depth.
• Stn L2: The current speed at the surface was generally higher than at the bottom. Current directions were scattered in all directions.
• Stn L3: The current speed at the surface was generally higher than at the bottom. Current directions were mainly between 170° and 270° up to 12 m, with scattered directions at the bottom.
• Stn L4: The current speed at the surface was generally higher than at the bottom. Current directions were mainly between 170° and 220° at the surface up to 3 m, with scattered directions at the bottom.

Geophysical Survey Findings

The seabed investigations, conducted through side scan sonar and shallow seismic surveys, concluded that the seabed is predominantly composed of sedimentary rocks. Finer sediment patches were scattered across the seafloor. Man-made objects and sunken boats were observed at various locations. The sub-seabed comprised compact sediment or sedimentary rock. The reduced penetration of acoustic waves due to the higher acoustic impedance of the sub-seabed indicated consolidated sedimentary formations. However, no hard rocky (basement rock) formations were detected within the penetration limit. Boreholes at discrete locations will be necessary to confirm the nature, type, and thickness of different geological formations below the seabed.