ADCP's Application to Ocean Current Measurement in Port of Honolulu

1. Where is the Port of Honolulu?

Port of Honolulu is in Honolulu, Hawaii. It is a deepwater seaport in the Pacific Ocean and is a vital transportation hub for the Hawaiian Islands.

Port Scale and Throughput

The port plays a major role in the handling of all types of cargo. It handles a large volume of cargo that ranges from containers, automobiles, and bulk commodities like petroleum products and building materials. The throughput of Honolulu's port is crucial for the economic well-being of the islands by allowing the importation of a wide variety of consumer goods and the exportation of local products such as agricultural produce and handicrafts.

Routes and Business

It is also hooked up with the main shipment lanes across the Pacific. The variety of business within this port is many and mainly aimed at trade exchanges between Hawaii and the continental part of the USA and international, primarily focusing on Asia and Oceania. Examples include the large amounts of imports regarding foodstuffs, electronic items, and garment. These include exports from Hawaiian-grown fruits, coffee, and products relating to the various tourist industries within Hawaii.

Port Management and Operation

The port has a professional management team that governs the operations, efficient cargo handling, berthing of vessels, and safety. They cooperate with shipping companies, terminal operators, and regulatory agencies for smooth operations. The management also focuses on environmental protection and the adoption of sustainable practices to reduce the impact of port activities on the ocean environment.

Port Facilities

The port has berths that are fit for various vessels. Equipped with storage tanks for liquid bulk cargo, like petroleum, the port also has storage areas for dry bulk and general cargo. In addition to these, there are loading and unloading facilities such as cranes and conveyor systems for the movement of goods between the vessels and land transport modes.

Channels and Direct Routes

These channels in the Port of Honolulu are dredged so that ships could pass through it safely. It directly connects with other ports in Hawaii and through the Pacific to major ports in the United States mainland, Asia, and Oceania, enabling the transportation of goods to a wide range of destinations.

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

Navigation Safety

Measurement of currents in the Port of Honolulu is critical for ensuring that ships sail safely. Currents around Hawaii are quite complex and may change throughout the year. Currents can impact a ship's speed and maneuverability. For example, strong tidal currents and oceanic gyres may make docking and undocking more difficult. Accurate current measurements will help the captains of the ships to plan better approaches and prevent collision or running aground.

Efficient Port Operations

Knowledge of currents also assists in ensuring efficiency in handling cargo. Currents may affect ships lying off during the intake of cargo or during cargo discharging. In planning for efficient times for scheduling facilities of berthing and deployment of facilities handling cargo, there is increased efficiency in a flow of commodities without delay on cargo transfer.

Environmental Protection

This becomes more important in the event of dangerous spills, like oil and chemicals. In that case, knowledge of the ocean currents will be much more crucial, as it will dictate the direction and speed at which the pollutants will spread. By having a correct measurement of the currents, the response teams can then take better measures in containing and cleaning up the spill to reduce further damage to the ocean's environment.

The ADCP current meter represents a more modern and convenient method of ocean current measurement than the previously used methods. It is capable of delivering real-time and continuous data across various depths and areas of the port water, hence giving a comprehensive view of the prevailing situation.

3. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of the Doppler effect. They send acoustic signals into the water. These acoustic waves scatter off moving particles in the water, like sediment, small organisms, or bubbles. When these waves are reflected back to the ADCP profiler, the frequency of the reflected waves is different because of the Doppler effect.

This shift in frequency varies linearly according to the velocity of the moving particles and hence, the velocity of the water current. This phenomena of shift in frequency is exploited by the ADCP meter for calculating current velocity and direction at discrete depths.

Ship-borne ADCP

A ship-borne ADCP is installed on a ship. While the ship is sailing through the water, the ADCP flow meter sends acoustic pulses downwards and laterally. It measures the current velocity at different depths along the path of travel of the ship. The data collected provides an extremely detailed profile of the current structure in the area covered by the movement of the ship. It is useful in surveying a wide area of the port water while the ship is traveling.

Fixed ADCPs

Normally, fixed ADCPs are installed on structures like piers, buoys, or the seabed. They can continuously monitor ocean currents that pass by a certain location. By standing at a fixed position, they are able to provide long-term and stable data about the current conditions at that particular point. This is very helpful in understanding the temporal and spatial variations of the currents in the port area.

4. What is needed in place for high quality measurement of currents within Port of Honolulu?

Reliable Material Equipment

This equipment has to be of reliable material to create high-quality measurement of current. This would mean putting up with the harsh salt marine environment, taking in corrosion and wave impacts of fluctuating temperatures. The equipment casing has been preferably made out of a metal alloy of Titanium. It is resistant to corrosion, which is necessary to deal with the corrosive nature of seawater. Besides this, it has a high strength-to-weight ratio, providing strength and keeping the weight of the device relatively low.

Desirable Equipment Characteristics

A small size and light weight are advantageous. A smaller and lighter device is easier to install and operate, whether on a ship or on a fixed structure. Low power consumption is also desirable. This will enable the equipment to operate continuously for a long period without frequent battery replacement or a large power supply.

Cost-effectiveness

Cost-effectiveness is another important aspect for large-scale measurement in the port area. The equipment should have a reasonable cost to enable deployment in a large number. This helps in obtaining a more comprehensive understanding of the current situation across different parts of the port.

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

Based on Usage Purpose

• Ship-borne ADCP: If the primary purpose is to obtain current information during a ship's voyage or for navigation-related studies, then a ship-borne ADCP is appropriate. It can cover a wide range of the port area as the ship moves around.
• Bottom-mounted ADCP: For long - term and fixed - point monitoring of the currents near the seabed or in areas close to the port's infrastructure, bottom-mounted ADCPs are a good choice. They can provide stable and continuous data about the current conditions at specific locations.
• Buoy-mounted ADCP: In cases where the currents are to be monitored in open water areas or in areas where it is not feasible to install a fixed device on the seabed, buoy-mounted ADCPs are helpful. They can float with the waves and tides while measuring the currents.

Based on Frequency Selection

The frequency of operation of an ADCP depends on the depth of water. For example, the 600 kHz ADCP will have a water depth of about 70 meters or less, with high-resolution data. A 300 kHz ADCP has an operating range for water depths up to around 110 meters and a balance between resolution and measurement range. The ADCP of 75 kHz would be more appropriate for deeper waters, up to about 1000 meters deep, and would be useful for understanding the current conditions in deeper parts of the port area.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, there is also a Chinese brand, China Sonar PandaADCP, which is worth considering. It is made of all-titanium alloy material, providing excellent durability and has an impressive cost-performance ratio. You can find more information about it on their website: (https://china-sonar.com/).

In conclusion, the application of ADCPs to the ocean current measurement in the Port of Honolulu is extremely important. The choice of proper equipment and using them properly can get accurate and useful current data to support safe and efficient operation of the port.

Here is a table with some well known Acoustic Doppler Current Profiler(ADCP)  instrument brands and models.