ADCP's Application to Ocean Current Measurement in Wellington Port

1. Where is Wellington Port?

Wellington Port is located at the southern tip of New Zealand's North Island. Situated in Wellington, the capital city of New Zealand, it occupies a strategic position on the Cook Strait, which separates the North and South Islands.

Port Scale and Throughput

The Wellington Company is one of the major ports in New Zealand, commanding a considerable volume of cargo and passenger traffic. Wellington has a diversified cargo portfolio. It remains a major entry and exit gateway for general cargo, including consumer goods, building materials, and machinery. The port deals in a significant volume of bulk cargo consisting of coal, grain, and fertilizers. Its annual throughput has been on the increase for years due to the growing economic activities in the region and its role of being a vital transportation hub. Container traffic is also one of the important parts of its operations, with the port accommodating a large number of container vessels.

Routes and Business

The port has an extensive network of shipping routes. It has regular services to major ports throughout the Asia - Pacific region, Europe, and the Americas. Through it, international trade is obtained by allowing good in and outside New Zealand. Wellington Port offers a variety of business services. It offers fast cargo handling facilities in state-of-the-art cranes and conveyor systems which load and discharge various types of cargos either quickly or with great care according to their requirement. Apart from that, the port offers well-equipped warehousing facilities for short- and long-term storage. Additionally, this involves services in connection with ship maintenance, fueling, and provisioning, making the port a full-service entity for shipping operations.

Management and Operation of Port

Wellington Port is governed by a very professional and proactive team of management. The focus of the management is on sustainable development, safety, and efficiency in operations. They invest in continuous infrastructure improvement to keep up with the evolving demands of the shipping industry. The port operates 24/7, with a well - coordinated system of pilots, tugboats, and dockworkers. Safety is a top priority, and strict safety protocols are in place to ensure the smooth and secure movement of vessels and cargo. The port also follows rules concerning the protection of the environment by adopting measures that reduce its negative impact on the marine environment surrounding it.

Port Facilities

The port facilities are state - of - the - art. It is a multi-purpose port with several berths, one of which includes deep - water berths. These can handle large - sized vessels like container ships, bulk carriers, and cruise ships. These are the berths, equipped with different types of cargo-handling gear: for example, gantry cranes, mobile cranes, and fork lift trucks. Besides general facilities, there is a liquid bulk handling facility like oil terminals with pipelines and storage tanks. Besides, Wellington Port is provided with modern navigation aids like lighthouses, radar systems, and GPS-based navigation systems to ensure safe entry and exit of vessels, especially in the usually unpredictable weather of the Cook Strait.

Channels and Direct Navigation

The main shipping channel of Wellington Port is carefully maintained to ensure a safe passage for vessels. The depth of the channel is regularly checked and dredged when necessary to accommodate the ever-increasing size of modern ships. Pilot services are available to guide vessels through the channel, taking into consideration the local currents, tides, and weather conditions. The port has shipping routes to nearly all major international ports directly, increasing its connectivity without detaching it from increasing the transit times of goods movements, hence its competitiveness in world shipping markets.

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

Measuring the ocean currents is of great significance when it comes to many aspects concerning the management at Wellington Port.

Vessel Navigation Safety

Cook Strait, wherein Wellington Port is situated, has complex and usually changing ocean currents. Such will obviously have a very important effect on the navigation of vessels. The strong current may alter the speed course, or maneuverability of any vessel. For example, while the vessel is entering the port or leaving it, the current may throw her off course and thereby increase the likelihood of collision with other vessels, rocks, and port structures. With correct measurement of currents of the ocean, pilots and masters of ships are able to make more knowledgeable decisions, change their method of navigation, and allow vessels to pass through safely.

Cargo Handling Efficiency

These could also be further influenced to affect cargo handling operations in Wellington Port through ocean currents. In this instance, when the ship is alongside the berth, vessel movements due to currents might interfere with cargo loading or unloading activities. If not correctly factored into account, there could be delay times in handling cargo, because it may affect correct alignments between the vessel and cargo-handling gear. Real-time data about ocean currents helps port operators in scheduling cargo operations. It ensures correct positioning of the equipment and minimizes the time taken to load and unload cargo, improving the overall efficiency at the port.

Protection of the Environment

Measurements of ocean currents play a very important role in Wellington Port for protection of the environment. The port is enveloped by a rich marine ecosystem, and any pollution incidents considerably take their toll on this ecosystem. In the occurrence of an oil spill and other forms of pollution, knowledge of ocean currents would provide a good prediction of the spread of the pollutants. The data will in turn, be useful for the timely deployment of all the control measures for pollution like oil-skimming vessels, containment booms and dispersants. With proper prediction about the movement of the pollutants based on current data, the port would take necessary precautionary measures to reduce environmental damage.

Of all the ocean current measurement methods available, the Acoustic Doppler Current Profiler(ADCP) is more advanced and convenient. It provides very high-resolution data in real time, which plays a key role in the effective management of the Wellington Port.

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

ADCP Measurement Principle

The working principle of the ADCPs is based on the Doppler principle. An ADCP sends out acoustic waves into the water. These are reflected back from small particles suspended in the water, like plankton, sediment, or small air bubbles. As the water is moved by an ocean current, these particles are also moved. When the acoustic waves are reflected back from these moving particles, their frequency is different from the frequency of the emitted waves. That constitutes a shift in frequency, commonly called the Doppler shift, which is proportional to the speed of the particles and hence that of the current. The ADCP current profiler estimates the speed and direction of water at several depths by making an accurate measurement of this Doppler shift.

ADCP in Port Current Measurement - Specific Methods

Ship-borne ADCP

A ship-borne ADCP is fitted out on a vessel. While the ship is in motion, the water current along the track of the ship could also be measured by the ADCP. Mostly, a ship-borne ADCP has multiple acoustic beams, up to four or even more. By analyzing the Doppler shifts from different beams, the ADCP flow meter can also determine three-dimensional velocity components of the water current. This method is useful in conducting large-scale surveys of the port area. As such, it can be used in mapping the overall current patterns in Wellington Port, providing much information regarding the general flow of water within the port and in the approaches to the port.

Fixed ADCP

A fixed ADCP is usually installed at a certain point in the port, for example, on the seabed or attached to a pier. It monitors the current water continuously at that particular point. Fixed ADCPs represent a very suitable tool for long-term monitoring of current patterns in areas where consistent data is to be collected. In fact, a fixed ADCP near any berth can provide information on the local current conditions over time that may be impacting vessel berthing operations. These can be developed into better berthing procedures and anticipate potential issues arising from current-induced vessel movement.

4. What is required in order to have high-quality measurement of the currents at Wellington Port?

Equipment Material Reliability

Regarding high-quality measurement of currents in Wellington Port, the reliability of the equipment material cannot be compromised. The marine environment in the port is harsh, with conditions like saltwater corrosion, a high pressure of water, and possibly heavy mechanical impacts. Such conditions require that the ADCP be made of special materials that will provide long-lasting resistance.

Small Size, Light Weight, and Low Power Consumption

The ADCP should be compact in size and lightweight. A small-sized ADCP is easy to install, whether on a ship or at a fixed location on the seabed or pier. It also gives less disturbance to the natural flow of water. Light-weight ADCPs are easier to handle and transport, reducing installation effort. Especially for long - term monitoring applications, low power consumption is required. It can operate for a long time and avoid the frequency of changing batteries or connecting to large - scale power sources. In particular, this will be very important for fixed - type ADCPs that are deployed in remote locations within the port.

Low Cost for Large - scale Measurement

In order to carry out large-scale current measurements in Wellington Port, the cost of the ADCP should not be too high to enable multiple deployments of ADCPs in different locations across the port for a better understanding of the current field. A low-cost ADCP will also make the technology more accessible to research institutions and smaller port-related operations.

The housing of the ADCP shall be made from titanium alloy. Titanium alloy exhibits excellent corrosion resistance against the corrosive effects of saltwater in the port environment. It can also maintain its integrity over long periods, reducing the need for frequent replacement. Besides, titanium alloy is lightweight, meeting the requirement for easy installation and operation. It also has high strength and can protect the inner components of the ADCP from mechanical impacts, ensuring the long-term reliability of the device.

5. How to Choose the Right Equipment for Current Measurement?

Based on Usage

Ship-borne ADCP

For this purpose, in case the objective is to conduct a large-scale survey of the existing pattern at Wellington Port, the first choice should be a ship-borne ADCP. A ship-borne ADCP could cover a broad area of the port in a very short time and thus can provide a large-scale view of the current distribution. This may be useful in understanding the general flow of water within the port and at the approaches to the port.

Bottom - mounted (Sitting - bottom) ADCP

A bottom-mounted ADCP is appropriate for long-term measurement at a particular point, for example near a berth or in a critical section of the shipping channel. In Wellington Port, it can be used to continuously monitor the current conditions at these key locations, providing valuable data for berthing operations and channel management.

Buoy - type ADCP

In places where the current should be monitored where the depth is highly variable, an ADCP might be needed in a moving water-mass, whereupon a buoy - type ADCP could be advantageous. For these, deployments could be performed open - water in several areas of the port. Thus, while it floats with any given water current, data can also be provided in real-time.

Based on Frequency

The choice of the ADCP frequency depends on water depth. ADCP with frequencies as high as 600kHz is feasible to use at depths within 70m of water depth. This frequency provides high resolution at relatively shallow water, as in some locations such as near the berth areas or relatively shallower areas of a port like that in Wellington. For water depths up to 110m, a 300kHz ADCP would be more appropriate. It would have a deeper penetration in water with good measurement accuracy. For very deep waters, such as those with a depth of 1000m, a 75kHz ADCP is recommended. Lower frequencies can travel longer distances in water, allowing for current measurements at greater depths.

There are quite some leading manufacturers for ADCPs in the market, among them Teledyne RDI, Nortek, and Sontek. However, for those in need of an economical and quality option, one must take a look at the Chinese brand China Sonar PandaADCP. It is fabricated from all-titanium alloy materials to make sure it is extremely durable in the sea environment. With an incredible cost-performance ratio, this can be a great solution for current measurement in Wellington Port. For more information, visit their website: (https://china-sonar.com/).

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