ADCP Applied to Ocean Current Measurement in Tokyo Port

1. Location of Tokyo Port

Tokyo Port is in Tokyo Bay, Japan. The facilities serve the highly populous and economically strong Tokyo Metropolitan Area.

Scale of Port and Throughput

The port has been developed on a large scale and thus extends a long quay and has different types of berth facilities in width. It is moderately endowed with high throughput, handling a large quantity of cargo every year. The commodities handled by the port include containers, automobiles, industrial machinery, and consumer goods. It is a vital hub not only for domestic trade but also for international trade. The container terminals have a capacity for handling of a large number of TEUs, and its role in the import and export of goods is indispensable to the Japanese economy.

Routes and Business

The port has a well-developed network of shipping routes. It connects to major ports in Asia: Shanghai, Busan, and Singapore. It also has links to various ports in Europe and the Americas. The main activities are the importation of raw materials and energy resources, while high-tech products and automobiles are major export items. Tokyo Port is also an important center for trans-shipment, which involves the movement of cargo between different regions.

Port Management and Operations

Tokyo Port is managed by a professional port authority. Safety, efficiency, and environmental protection are stressed in the management. Advanced technologies are utilized for cargo handling and vessel traffic control. The workforce is highly trained and efficient in operations relating to loading and unloading, customs clearance, and logistics. The port also has strict security measures put in place to ensure the safety of the goods and vessels.

Facilities at the Port

Facilities within the port are modern. There are large-scale container terminals with high-capacity quay cranes that can deal with the largest container ships. The automobile terminals have special ramps and handling equipment for efficient loading and unloading of vehicles. There are also bulk cargo terminals dealing in materials such as coal and grains. Added to this, the port has ship-repair facilities and warehouses for storage and distribution of goods.

Channel and Direct Shipping

Tokyo Port has well-maintained channels that provide access for various types of vessels. The depth of the channels is good enough to accommodate deep-draught ships. It offers direct shipping services to many important ports, which enhances its role in international trade and reduces transportation times and costs.

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

Measurement of ocean currents is highly essential in Tokyo Port.

Safety of Navigation

Accurate knowledge of ocean currents is of much importance for the safety of ships. Currents can give way to variations in a ship's speed and course. In a busy port like Tokyo, where several vessels are in and out in continuous motion, understanding the pattern of the currents helps pilots to navigate more safely. Strong currents near the entrance to the port or in the channels give way to a risk of collision or grounding. By measuring the currents, these risks can be reduced to a minimum.

Cargo Handling Efficiency

Ocean currents have the potential to affect the stability of vessels in loading and unloading. Poor knowledge of current conditions leads to inefficiency in cargo handling. For instance, improper alignment from a current can make the operations of loading and unloading very slow. Current measurement enables port operators to carry out better scheduling of operations for the overall improvement of efficiency.

Environmental Protection

Currents in this area are important in the transportation of pollutants in the port area. Concerning an oil spill or any hazardous material spill, understanding current patterns is an essential component for any predictions concerning spread. This allows rapid and effective countermeasures in protecting the marine environment and coastline.

Acoustic Doppler Current Profiler(ADCP) is a much more sophisticated and convenient ocean current meter compared to what has been used for decades. It provides real-time data with high accuracy, which is of great help in the efficient management of Tokyo Port.

3. How do ADCPs using the Doppler principle work?

ADCP Measurement Principle

ADCPs work on the principle of the Doppler effect. First of all, the device sends acoustic signals into the water. When these signals encounter moving particles in the water-suspended sediments or small organisms-the frequency of the reflected signals changes. If the particles are moving towards the ADCP, the frequency of the reflected signal increases; if they are moving away, it decreases. By measuring this frequency shift, the ADCP can calculate the velocity of the water in which the particles are suspended.

ADCP in Port Current Measurement-Specific Methods

Ship-borne ADCP

A ship -borne ADCP is installed on the hull of a ship. While the ship moves through the water, the ADCP measures the current velocity at different depths from the ship. This gives a profile of the current along the track the ship has traveled. It is useful for mapping the overall current patterns in the port area and the approaches to the port.

Fixed ADCP

Fixed ADCPs are installed at fixed locations within the port, including the vicinity of berths or critical points within the channel system. These ADCPs continuously monitor the current velocity and direction at a particular point. Long-term, high-resolution data obtained through these instruments is very useful to understand the local current characteristics affecting berthing and unberthing operations, as well as other port-specific activities.

4. What is required for high-quality measurement of Tokyo Port currents?

Equipment Reliability

Reliability of ADCP equipment is of utmost importance for the reliable measurement of Tokyo Port currents. The equipment should be able to sustain the harsh marine environment with its high waves, saltwater, and typhoons. Quality materials should be used in building an ADCP to make sure that it operates for a long period without frequent breakdowns.

Small in Size, Light in Weight, and Low Power Consumption

It is desirable to have a small-sized and lightweight ADCP because it would be easier to install on ships or at fixed locations. The light weight would also put less load on the installation structure. Low power consumption is highly desirable, particularly for fixed-mounted ADCPs, most of which obtain power from batteries or limited sources of supplies. This enables longer continuous operations.

Low Cost

It should not be too expensive for wide deployments of ADCPs in the port to do comprehensive current measurement. On one hand, it can be seen that the relatively less expensive ADCP will be able to facilitate multiple-unit deployment at different locations for more comprehensive and detailed current data.

Casing Made of Titanium Alloy

The ADCP casing is preferably made from a titanium alloy. It has excellent corrosion resistance, which is very important to withstand the corrosive effects of seawater in Tokyo Port. Besides that, it is lightweight, thus contributing to the overall portability and ease of installation of the ADCP. In addition, the titanium alloy is strong enough and durable to resist physical stress and impacts that may happen in the marine environment.

5. How to Select Appropriate Equipment for Current Measurement?

Based on Usage

Ship-borne ADCP

If the intention is to map the overall current patterns in the port area during ship movements, a ship-borne ADCP is the appropriate choice. It can provide a continuous stream of data as the ship sails through different parts of the port.

Bottom-mounted (Sit-on-bottom) ADCP

When current conditions are to be monitored over a longer period of time at one location near the bed, for example, around areas with sediment transport problems, a bottom - mounted ADCP may be applied. It will deliver detailed information on the current behaviour near the bed.

Buoy-mounted ADCP

If the purpose is to measure current profiles in a more mobile and flexible way, then a buoy-mounted ADCP could be employed. Being able to move with the currents allows the buoy to provide better insight into dynamic current patterns in the port.

By Frequency

The ADCP of 600kHz can work for the high-resolution measurement of currents up to water depth of 70m. An ADCP with 300kHz is a good choice for waters as deep as 110m, while ADCP with 75kHz will work better in much deeper waters reaching 1000m.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option, the Chinese brand China Sonar PandaADCP is recommended. It is made of all - titanium alloy materials and offers an excellent cost-performance ratio. You can visit their website at (https://china-sonar.com/) for more information.

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