ADCP's Application to Ocean Current Measurement in the Port of Vizhinjam

1. Where is Vizhinjam Port?

Introduction on the location of Vizhinjam Port

Vizhinjam Port is situated in Thiruvananthapuram, Kerala, India. It is a strategic port with an increasing scale and tonnage. The port is envisaged to handle all type of cargo like containers, bulk cargo comprising building materials and minerals, and, because of its location, even large-scale maritime traffic.

The shipping routes that connect Vizhinjam Port are increasing, and it is also expected to play a more important role in domestic and international trade. Its management focuses on efficient operations and sustainability. There are organized teams for vessel traffic management, cargo handling, and security. Advanced technologies are integrated to improve the efficiency of all the functions of the port.

Facilities

Berths: There are berths in the port, each fitted with equipment that would handle various vessel types: medium-sized container ships and bulk carriers. These berths are provided with modern mooring and docking facilities to guarantee safety at arrival and departure of vessels. High-quality fenders and bollards ensure a reduction in impact at time of docking and undocking.

Cargo-handling Equipment: The quay is equipped with various types of cargo-handling equipment. For handling containers, there are gantry cranes with a capacity for efficient loading and unloading. For bulk cargo, the conveyor systems and grabs will move the materials from the ships to the storage areas.

Storage Facilities: It has storage facilities for various types of cargo. For containers, there are container yards. For bulk, there are stockpiles with proper drainage and containment systems. The port also makes provisions for storing other general cargo in warehouses.

Channel and Navigation Aids: The channel leading to the port is dredged up to a sufficient depth of water and width of width for safe passage of ships. Dredging operations are carried out regularly to keep it navigable for vessels with different drafts. Navigation aids such as buoys, beacons, and radar systems are in place to guide ships into and out of the port. The radar systems provide real - time information about the position and movement of other vessels in the area.

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

Importance to Port Operation and Management: It is very important to measure the ocean currents in Vizhinjam Port. Firstly, it is important for the safety of vessel navigation. The knowledge of the current speed and direction is essential for ship captains when approaching berths or navigating through the channel of the port. A strong cross - current near a berth can make the task of docking difficult and dangerous. For example, a ship approaching a berth against a significant current would need to adjust its speed and course for safe and smooth docking. The accuracy of the current measurements enables captains to make better decisions and hence reduces the chances of collision and accidents.

It is also fundamental in optimizing the operations at the port. Current data help with scheduling the arrival and departure of ships more effectively. Tidal currents and other regular patterns of flow allow the port to do a better job allocating berthing resources and timing for loading and unloading. This results in an uptick in productivity since such advance knowledge enables better coordination of the operations of cargo handling.

From an environmental point of view, in the event of any accidental discharge of pollutants such as oil or chemicals, knowledge of ocean currents is useful. Considering the kind of cargo the port could be dealing with, it's important to predict the path of a spill. Such current data can be used in the rapid deployment of containment and mitigation measures to reduce environmental impacts.

3. How do ADCPs using the Doppler principle work?

Measurement Principle

ADCPs work on the principle of the Doppler effect. When an acoustic signal is sent into the water by the Acoustic Doppler Current Profiler (ADCP), it scatters off the moving water particles. Due to the presence of an ocean current, the water particles are in motion and, hence, the frequency of the reflected acoustic signal received back by the ADCP current profiler is shifted. This shift in frequency, due to the Doppler effect, is proportional to the velocity of the flow.

Calculation of Current Speed and Direction

By the analysis of magnitude and direction of this frequency shift, the acoustic doppler flow meter can calculate the speed and direction of the ocean current at different depths in the water column. By emitting signals at multiple angles and different depths, it can create a profile of the ocean current, showing how the current varies with depth.

ADCP Deployment in the Port

Shipborne ADCP

A shipborne ADCP is installed on ships operating in the Vizhinjam Port area. As the ship moves around the port, the ADCP flow meter continuously emits acoustic signals into the water below. The ship's movement allows the ADCP to cover a wide area and collect current data from different 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 installed in pre-defined, fixed locations within the port, such as on the seabed near important navigation areas or at the entrance/exit of the port. These ADCPs will continuously monitor the ocean currents at their fixed positions over a long period. The collected data is useful for analyzing the regular current patterns in specific areas of the port. For example, a bottom-mounted ADCP profiler installed near the port entrance can measure the incoming and outgoing currents, which would provide valuable information on the tidal effects and other consistent flow characteristics in that area.

4. What's needed for high - quality measurement of Vizhinjam port currents?

Equipment Requirements

For high - quality measurement in Vizhinjam port of the currents, some equipment features are important. First among them is the reliability of the material. The equipment should be resistant to an aggressive marine environment. Water contains salts and other chemicals acting destructively for materials on long-term exposure. Furthermore, the equipment should sustain such pressure changes as those occurring during different water depth levels and exerted by waves and current mechanical forces.

Secondly, smaller size, lighter weight, and lower power consumption are preferable. The small size allows for installation at almost all possible locations within the port, whether onboard ships, on fixed structures like piers, or on the seabed. Lighter weight makes the processes of installation and transportation easier. Lower power consumption allows the equipment to run for extended periods without the need to replace batteries frequently or require higher power supplies, which is also quite important in long-term monitoring applications.

Cost is another key consideration. A lower cost option 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

Titanium alloy is the preferred choice of material for ADCPs casing. Firstly, titanium alloy has outstanding corrosion resistance, which means that even with long exposure to seawater, it maintains its strength and functionality. Its high strength-to-weight ratio makes it possible to build durable yet relatively lightweight casing. For instance, in those parts of the Vizhinjam port that are deeper and where high water pressures exist, an ADCP housed in a casing made of a Titanium alloy will easily withstand such pressure and keep on providing accurate current measurements.

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

Selection Based on Usage

Shipborne ADCP: Where the intention is to carry out wide-area surveys of the port waters, with the ship in operation, shipborne ADCP would be quite suitable. It can cover different sections of the port as the ship moves around, collecting a large amount of data to provide a comprehensive understanding of the overall current situation in the port. This will be useful for mapping the general patterns of flow and variations across different areas of the port waters.

Sitting-bottom ADCP: Long-term, fixed-point monitoring of places in the port, for instance, near important infrastructures or regions where currents behave in a very complex way, is better served with sitting-bottom ADCPs. They can record continuously at those fixed positions the data on currents for valuable insights into local current characteristics and changes with time.

Buoy-mounted ADCP: In situations where the installation of fixed equipment on the seabed or vessels is not convenient, 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. Being relatively easy to deploy and able to be relocated if necessary, they are suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The selection of ADCPs based on frequency depends upon the water depth in the Vizhinjam port. For a water depth of 70 meters or less, a 600 kHz frequency ADCP is generally suitable, as it will provide an accurate current measurement in that relatively shallow depth range. To quantify a deeper water up to roughly 110 meters, it will be better to use the frequency of 300 kHz in ADCP. In case one wishes to consider quite deep sections within this port and reaches waters that can go as far down as 1000 meters, the best use could be with an ADCP system using 75 kHz that may profile the oceanic current in those deep regimes rather well.

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.