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

1. Where is Turku Port?

Overview of Turku Port

Turku Port is situated within the city of Turku, Finland. It represents a large-scale port with high throughput. Thus, the port is an important transport link between Finland and other states, with container cargo transportation, bulk cargo transportation-like forest products-wooden logs, pulp, and some industrial and agricultural products.

Its shipping links are very extensive, encompassing regular routes through numerous European ports and other international destinations. The port is of prime importance to the Finnish economy for imports and exports. There has been good management at Turku Port with utilization of modern technologies in managing vessel traffic, cargo handling, and other operations. Functions such as berthing operations, cargo storage and distribution, and customs procedures are well managed with well-coordinated teams.

Port Facilities

Berths: The port has different berths for receiving various kinds of vessels. There are deep - water berths for large container ships and bulk carriers. These berths are equipped with advanced mooring and docking facilities. The use of high - strength bollards and fenders ensures the safe arrival and departure of ships, even in challenging weather conditions and strong currents.

Cargo-handling Equipment: All types of cargo-handling equipment line up along the quay. In the case of container handling, there are modern gantry cranes, which have greatly increased the speed of loading and unloading operations. For bulk cargo, conveyor systems exist and grabs for materials such as timber and pulp. There are also forklifts and other handling equipment for general cargo.

Storage facilities: Huge storage facilities for various categories of cargo. For containerized cargo, there is an organized container yard that allows easy and efficient storage and retrieval, bulk stockpiles with a system that protects against the weather and spill-containment facility, other general cargo warehousing, and cold storage facilities in respect of perishable commodities.

Channel and Navigation Aids: The channel is dredged to a suitable depth and width for safe access of ships into the port. Dredging operations are also continuously done in order to keep it accessible to vessels with large drafts. Navigation aids include buoys, beacons, and radar systems that provide guidance to ships entering or leaving the port. The radar systems give real - time information on the position and motion of other vessels around us.

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

Importance to Operate and Manage a Port

The measurement of sea currents in the Turku harbor is very important. First and foremost, for the safe traffic of vessels. The knowledge of the actual speed and direction is very important to ship captains approaching berths or navigating through the channel. A strong cross-current near a berth can make docking a difficult and risky process. For example, a ship approaching a berth against a strong current may need to adjust its speed and angle of approach to ensure a smooth and safe docking. Captains can make rightful decisions and minimize the chances of collisions and other accidents because of accurate current measurements.

This again, helps in optimizing the operation of the port. Present information on currents enables better scheduling of arrival and departure of ships. In addition, understanding tidal currents and other periodic flow features will assist port authorities in managing berth allocation and planning loading/unloading activities more efficiently. Productivity also increases since this allows for better coordination of cargo-handling operations.

Moreover, from an environmental perspective, in case of an accidental spill of pollutants such as oil or chemicals, knowledge of ocean currents is valuable. Given the nature of the cargo handled in the port, predicting the spread of a spill is crucial. The current data can be used to quickly implement containment and mitigation measures to minimize environmental damage.

These currents can be measured more precisely and conveniently with Acoustic Doppler Current Profilers (ADCPs) than the conventional methods.

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

Measurement Principle

ADCPs work on the principle of the Doppler effect. When an acoustic signal is transmitted by the ADCP profiler into the water, it scatters off the moving particles of water. 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 meter is shifted. This shift in frequency, by the Doppler effect, is proportional to the velocity of the flow.

Calculation of Current Speed and Direction

By analyzing the magnitude and direction of this frequency shift, the ADCP current profiler 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

A shipborne ADCP is installed on ships operating in the Turku Port area; while the ship is on the move around the port, it continuously sends acoustic signals into the water from the vessel. The movement of the ship allows the ADCP current meter to cover a wide area and collect current data from various locations. For instance, a research or inspection ship with a shipborne ADCP on a routine survey of the port can collect data for the current patterns over different parts of the port and give an overview of the water flow condition.

Fixed ADCPs are placed at specific, stationary locations within the port, such as on the seabed near important navigational areas or at the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period. The data collected is useful for analyzing the regular current patterns in specific areas of the port. For example, a bottom-mounted ADCP at the entrance of the port can measure the in-flow and out-flow currents, which will give an idea about the tidal effects and other steady flow features of that area.

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

Equipment Requirements

For high-quality measurement of the currents in Turku port, some characteristics of equipment are important. Firstly, material reliability is of great importance. The equipment should withstand the marine environment. Seawater contains salts and other chemicals which may destroy materials in a long perspective. The equipment also needs to stand pressure changes at different water depth and mechanical forces from waves and currents.

Second, it should have a smaller size, lower weight, and reduced power consumption. Compact size enables easier installation in several locations within the port, either on ships or on fixed structures like piers or seabed. Lower weight facilitates the installation and transportation process. Lower power consumption ensures the operation of equipment continuously for longer lengths of time without the need to replace batteries frequently or to use excessively higher supplies of power, especially in the case of long-term monitoring applications.

Cost is another critical consideration. The 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

The casing of ADCPs is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance, that is, it can resist the action of seawater when submerged for a long time without losing its structural integrity and functionality. Its high strength-to-weight ratio allows for the construction of a durable yet relatively lightweight casing. For instance, an ADCP flow meter equipped with a casing made from titanium alloy would be adequately resistant to increased pressures found in deeper parts of the Turku port and would manage to continuously measure currents with accurate results.

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

Selection Based on Usage

Shipborne ADCP: Where the intention is to do a wide-area survey of port waters, with ships under operation, shipborne ADCPs could be a good suit for the job. It should give various sections of the area under the port as a result of the movement of the ship with extensive data on the overall prevailing currents in the port area. That would be useful in mapping the general patterns of flow and its variation within different areas of the port waters.

Sitting-bottom ADCP: For the fixed point and long-term monitoring at certain places in the port, like important infrastructure or areas with complex current behaviors, a sitting-bottom ADCP should be more appropriate. Thus, they are capable of recording continuously the current data at those fixed positions and then provide valuable insights into the local current characteristics and changes over time.

Buoy-mounted ADCP: When it is not convenient to install fixed equipment on the seabed or on ships, buoy-mounted ADCPs can be used. They float on the water surface and are capable of measuring currents in the upper layers of the water column. Relatively easy to deploy and able to be relocated if necessary, they are suitable for the monitoring of certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The chosen frequency for ADCPs depends on water depth in Turku port. For areas where water depth is up to 70 m, an ADCP frequency of 600 kHz normally allows good accuracy in current measurements since this is a rather shallow depth range. For deeper waters, say, up to about 110 meters, a better proposition would be an ADCP flow meter with a frequency of 300 kHz. For really deep sections of the port where water depth reaches as much as 1000 meters, an ADCP of frequency 75 kHz should be preferred to ensure reliable profiling of the ocean currents at such large depth.

There are several well - known ADCP current 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.