ADCP's Application in Measuring Ocean Currents at Kolkata Port

1. Where does Kolkata Port Lie?

Kolkata Port Overview

Kolkata Port, also known as the Kolkata Dock System, is situated in the city of Kolkata, West Bengal, India. It is one of the major ports in the country and has a rich history in maritime trade. The scale of the port and its throughput is huge, facilitating the handling of an extremely diverse range of cargo, from jute and tea to coal, iron ore, and containers.

The shipping routes of Kolkata Port connect it to various ports in India and overseas. It serves as a crucial gateway for trade in the eastern and northeastern parts of India. The management and operation of the port are efficient and involve multiple departments working in tandem. There are teams for vessel traffic management, cargo handling, and customs procedures. Operations are optimized by applying advanced technologies such as automated cargo-tracking systems and digital means of communication.

Port Facilities

Berths: The port has a number of berths, all of different characteristics. There are berths for large-sized cargo ships and for smaller vessels. The modern facilities of mooring and docking in these berths ensure safe arrival and departure of ships.

Cargo-handling Equipment: Along the quay, there is a range of cargo-handling equipment. For bulk cargo like coal and iron ore, there are conveyor systems and grabs. The containers are loaded and unloaded by means of gantry cranes. There are forklifts and other transfer equipment for general cargo handling.

Storage Facilities: There are vast storage facilities for various types of cargo. In addition, there are warehouses for the storage of tea, jute, and other general cargo. Ample stockyards are also available for bulk goods such as coal and iron ore. Within the port, containers can also be stored in an orderly fashion.

Channel and Navigation Aids: The channel of the port is kept at a sufficient draft and breadth for safe admission and exit of ships. Dredging is done on a regular basis to maintain its navigability. Navigation aids like buoys, lighthouses, and radar systems are installed to help the ships.

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

Importance for Port Operations and Management

The ocean currents have immense significance in Kolkata Port. First, for the safety of vessel navigation: knowledge of the current directions and speeds is highly important for ship captains while approaching the berths or navigating through the channel. A strong cross - current near a berth can make docking a challenging task. Precise current measurements enable captains to correct the course and speed of the ship to ensure smooth and safe docking and reduce the risk of collisions.

Another very important reason is that it optimizes the port's operations. Present data enables a more efficient scheduling of the arrival and departure of ships. The port authorities will be able to manage the usage of berthing facilities and plan loading and unloading with a clearer knowledge of tidal currents and other periodic flow behavior. Productivity increases because cargo-handling operations can be better coordinated.

Knowledge of ocean currents is also useful from an environmental point of view, as this helps in predicting the spreading of pollutants in case of any accidental spill. As various cargos, including hazardous substances, are handled within the port, the information provided will help in quick responses to contain and mitigate environmental damage. Considering these factors, an accurate and convenient measurement method like ADCP current profiler is highly useful for ocean current measurement in Kolkata Port.

3. How do the ADCPs using the Doppler principle work?

Measurement Principle

The ADCPs rely on the Doppler principle for their working. When an ADCP flow meter emits an acoustic signal into the water, the moving water particles interact with the emitted signal. Due to the presence of the ocean current, the water particles are in motion and thereby frequency shift the reflected acoustic signal received back by the ADCP profiler. According to the Doppler effect, this frequency shift in general has a relation to the velocity of the water flow. The ADCP current profiler calculates from the frequency shift the speed and direction of the water flow. The ADCP current meter was able to profile the ocean current by emitting a signal at different angles and depths to show how the current changes with depth.

ADCP in Port Ocean Current Measurement Methods

Shipborne ADCP: One shipborne ADCP is installed on ships operating within the Kolkata Port area. While the ship moves around, the ADCP profiler continuously sends acoustic signals to the water below. The movement of the ship will then assist in the coverage of a wider area and collection of current data from several locations. For example, during a routine survey of the port by a research or inspection ship equipped with a shipborne ADCP, it can gather data on the current patterns across various parts of the port, providing a comprehensive understanding of the water flow situation.

Fixed ADCP: Fixed ADCPs are deployed in fixed positions in the port-for instance, on the seabed near areas of important navigational features inside the entrance/exit of the port. These long-term current measurements from these fixed-position ADCPs have been continuously monitoring the ocean currents at a fixed position. The data thus collected will help analyze the regular current pattern in specific areas in the port. For example, a bottom-mounted ADCP at the port entrance can measure the currents entering and leaving it, which will provide insight into the tidal effects and other steady flow behavior in that area.

4. What is required to measure the currents in Kolkata Port?

Equipment Requirement

For such high measurement quality of currents in Kolkata port, some general characteristics of the equipment are required. Above all, reliability of the materials is very important. The equipment should be able to bear the aggressiveness of the marine environment and corrosion caused by sea water. Commonly, seawater contains a number of salts and other chemicals that slowly corrode the material. The equipment should also resist changes in pressure for different levels of water and mechanical forces caused by waves and currents.

Secondly, smaller size, lighter weight, and lower power consumption are preferable. The compact size allows for easy installation at several places in the port, whether on ships, fixed structures like piers, or even on the seabed. A lighter weight makes the installation and transportation process easier. By being low in power consumption, equipment can operate continuously for long periods without frequent battery replacements or excessive power supply. This is particularly crucial for long-term monitoring applications.

On the other hand, cost is another key factor. A lower cost allows the port to deploy a larger number of measuring devices for more comprehensive current monitoring across different areas of the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing in ADCPs is best made from titanium alloy. There is excellent corrosion resistance from titanium alloy, thus making it to hold its structure and functionality even after being immersed in seawater for many years. High strength-to-weight ratio thus enables the making of a long-lasting casing that would be moderately light. For instance, an ADCP current meter with a casing made of titanium alloy will serve effectively in those deeper parts of Kolkata port where higher water pressures exist, providing continued current measurements accurately.

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

Selection Based on Usage

Shipborne ADCP: In such a case, this method can suit wide-area surveys in port waters with the ship in operation. With the movements of the ship, it can cover different sections of the port and amass data sufficient for a comprehensive understanding of the overall current situation in the facility. This further helps in mapping the general pattern of flow and its variations in the different subareas of the port waters.

Sitting-bottom ADCP: For long-term and fixed-point monitoring of specific locations within the port, such as near important infrastructure or areas with complex current behaviors, sitting - bottom ADCPs are more appropriate. Thus, they can continuously record the data of currents at those fixed positions and therefore provide an insight into the local current characteristics and their possible changes over time.

Buoy-mounted ADCP: The buoy-mounted ADCPs can be used when it's not convenient to install fixed equipment on the seabed or aboard ships. 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; they are thus suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The frequency for the ADCPs depends on the water depth in Kolkata port. For those areas where the water depth is up to 70 meters, an ADCP current profiler of 600 kHz is normally a good choice, as that can give quite accurate current measurements in this relatively shallow depth range. Where the water is deeper, up to about 110 meters, the use of an ADCP current meter at 300 kHz is more advisable. For the very deep parts of the port, with a depth reaching up to 1000 meters, an ADCP profiler frequency of 75 kHz is recommended to get reliable profiling of the ocean currents at such great depth.

There are several well-known ADCP flow meter 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.