ADCP in Dahej Port: Ocean Current Measurement

1. Where is Dahej Port?

Overview of Dahej Port

Dahej Port is situated in the Bharuch district of Gujarat, India. It is a major port with large-scale infrastructure and high-volume cargo handling capabilities. The port is one of the key players in maritime trade, with a large volume of cargo handled including LNG, petrochemicals, chemicals, and other bulk and containerized goods.

The shipping network of Dahej Port is quite vast, with a connection to many domestic and international ports. It acts as a vital gateway for industries in Gujarat and other nearby regions by allowing the import of raw materials and export of finished products. The management of the port is efficient, with advanced systems in place for vessel traffic control, cargo handling, and other port-related operations.

Port Facilities

Berths: It comprises several berths intended to handle different vessels of each type. There are the deep-water berths that deal with the big-sized carriers that carry LNG and containers of ships. The facilities comprising these berths include modern mooring and docking, which will safely guarantee the arrival and departure of boats. In these berths, one will find bollards and fenders of strong building which are meant to endure different forces during docking and undocking.

Cargo-handling Equipment: The port has special pumping and transfer systems for handling LNG and other liquid cargo. There are conveyor systems and grabs for bulk cargo. Gantry cranes are used for efficient container handling. The cargo-handling equipment is designed for high precision and speed to ensure quick loading and unloading of cargo.

Storage Facilities: There are extensive storage areas in the port. For LNG, there are large - scale storage tanks with advanced safety features such as cryogenic insulation and leak - detection systems. For other liquid cargo, there are storage tanks with spill - containment and fire - protection measures. There are also container yards and stockpiles for bulk materials.

Channel and Navigation Aids: The channel of the port is maintained to a suitable depth and width to allow the safe passage of ships. The dredging operations are often necessary to keep it usable by large-draft vessels. Navigation aids such as buoys, beacons, and radar systems guide ships into and out of the port. The radar systems provide real - time information about the position and movement of vessels in the vicinity of the port.

2. Why should we measure the ocean currents in the Dahej Port?

Importance for Port Operation and Management

The measurement of ocean currents is very important in Dahej Port. Firstly, for the safety of vessel navigation. The knowledge of the actual speed and direction is very important for captains of ships when approaching the berths or negotiating the channel. A strong cross-current near a berth can make the docking process challenging and hazardous. For instance, a ship that approaches a berth against a strong current may have to adjust the speed and angle of approach for smooth and safe docking. It helps the captains to make proper decisions by giving them the right current measurements to avoid accidents such as collisions.

The other crucial factor is that it provides a way to optimize the operations of the port. Present data facilitates an improved scheduling of the arrival and departure of ships. The understanding of tidal currents and other periodic flow phenomena by port authorities can better use berthing facilities and also plan loading and unloading activities. The productivity also increases as the cargo-handling operations could be planned and coordinated in a much better way.

In addition, knowledge about the ocean currents is important from the point of view of an environmental disaster in case some pollutant accidentally spills out into the sea. It can be predicted how far it will spread. Considering the type of cargo the port handles, such as LNG and petrochemicals, the current data can enable a quick implementation of containment and mitigation measures to avoid as much environmental damage as possible.

3. How do ADCPs using the Doppler principle work?

Measurement Principle

ADCPs work on the principle of the Doppler effect. When an Acoustic Doppler Current Profiler (ADCP) emits an acoustic signal into the water, it scatters off the moving water particles. As the water particles are in motion due to the ocean current, they shift the frequency of the reflected acoustic signal received back by the ADCP meter. According to the Doppler effect, this shift in frequency depends on the velocity of the water flow.

Calculation of Current Speed and Direction

From the magnitude and direction of this Doppler shift, the ADCP current profiler is able to determine the current speed and direction at various levels in the water column. By transmitting signals in multiple directions and at multiple depths, it can develop a profile of the ocean current, showing how the current changes with depth.

ADCP Deployment in the Port

Shipborne ADCP

A shipborne ADCP will be installed on ships operating in the Dahej Port area. The ADCP current meter is mounted on a moving vessel that travels around the port and continuously sends acoustic signals into the water. Movement of the ship enables the ADCP flow meter to cover a wide area for current data collection at different locations. For instance, a research or inspection ship with a shipborne ADCP that conducts a routine survey of the port can obtain current patterns across different parts of the port for an overall understanding of the water flow situation.

Fixed ADCP

Fixed ADCPs are installed in specific, fixed locations within the port, such as on the seabed near important navigational areas or at the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period. The data collected is useful for analyzing the regular current patterns in specific areas of the port. For example, a bottom-mounted ADCP installed near the entrance can measure the currents entering and leaving the port, which would give a fair idea of the tidal effects and other persistent flow features in that area.

4. What's required for high-quality measurement of Dahej port currents?

Equipment Requirements

Material Reliability

Measurement requires quality that should be able to tolerate such an aggressive marine environment. Salts and different chemical compositions present in seawater might make the equipment get worn by corrosion with time. Such equipment also needs to endure pressure changes due to various water depths and the mechanical forces exerted by waves and currents. Materials that build the current-measuring equipment need to have high resistance against corrosion and mechanical tension.

Size, Weight, and Power Consumption Smaller size, lighter weight, and lower power consumption are preferred. A more compact size allows for more flexibility during installation in multiple locations around the port; whether installed on ships, installed on fixed structures such as piers, or underwater installations. Lighter weight provides easier processes for installation and transportation. Lower power consumption ensures that the equipment can operate continuously for long periods without the need for frequent battery replacements or excessive power supply, which is especially important for long-term monitoring applications.

Cost-effectiveness

Cost is also a significant factor. A lower-cost option enables the port to deploy a larger number of measuring devices for more comprehensive current monitoring across different areas of the port.

Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. Because the corrosion resistance of the metal is excellent, it will keep its structure and function without any noticeable deterioration even if continuously submerged in seawater for several months or even more. Its high strength-to-weight ratio allows constructing a durable yet relatively lightweight casing. For instance, in the deeper parts of the Dahej port where higher water pressures are present, an ADCP profiler with a casing made of titanium alloy will be able to withstand these pressures and continue to give accurate current measurements.

5. How to Choose the right equipment for current measurement?

Selection Based on Usage

Shipborne ADCP

Shipborne ADCP is a good choice if the aim is to carry out wide-area surveys of the port waters while the ship is in operation. It can cover different sections of the port while the ship is moving around, collecting a large amount of data for an overall understanding of the current situation in the port. This serves to map the general flow patterns and variations across different areas of the port waters.

Sitting-bottom ADCP

In case the current monitoring at particular places of the port as near main infrastructure or zones of current behavior complexity should be provided in the long-term or fixed-point modes, sitting-bottom ADCPs are more appropriate. Such instruments are capable of continuously recording the current data at fixed positions with more valuable insight into local characteristics and its time variations.

Buoy-mounted ADCP

When it is not convenient to install fixed equipment on the seabed or on ships, buoy-mounted ADCPs can be used. They float on the water surface and can measure the currents in the upper layers of the water column. They are relatively easy to deploy and can be relocated if needed, making them suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Frequency Selection

A choice of frequency for ADCPs will depend on the water depth in Dahej port. For a water depth of up to 70 meters, the choice could be an ADCP flow meter with a frequency of 600 kHz, which should work fine with this depth range for relatively shallow current measurements. When the water is deeper, up to about 110 meters, a 300 kHz frequency ADCP current meter is more advisable. In very deep parts of the port, with a water depth of up to 1000 meters, the use of an ADCP current meter with a frequency of 75 kHz would be recommended to ensure reliable profiling of the ocean currents at such great depths.

There are several well-known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, there is also an excellent Chinese ADCP brand-China Sonar PandaADCP. It is made entirely of titanium alloy material, which not only ensures its durability in the marine environment but also offers an excellent cost-performance ratio. For more information, you can visit its official website: (https://china-sonar.com/).

Here is a table with some well known ADCP instrument brands and models.