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

1. Where is the Port of Rohuküla

The Port of Rohuküla is located in Estonia. It is a meaningful maritime facility that provides various functions in the context of Estonian and regional shipping.

Port Scale and Throughput

• The port is of considerable size, able to handle a high level of cargo. Its throughput runs the gamut of bulk cargo, such as grains and ores, general cargo, including industrial equipment and consumer goods, and it serves as a base for fishing vessels. The port is so structured that a whole range of ships and cargo is handled in an efficient manner.
• It has a number of berths with different characteristics to accommodate vessels of various sizes. This allows for the docking of both small - to - medium - sized local ships and larger cargo vessels that are involved in international trade.

Routes and Business

• Rohuküla port is well-connected with the domestic and international shipping route. Domestically, it connects with other Estonian ports, which facilitates internal distribution. Internationally, it is part of the Baltic Sea trade network and has connections to the ports in Scandinavia, other Baltic countries, and further afield in Europe.
• The main business activities involve cargo handling; in particular, loading and unloading operations for different kinds of cargo. Besides this, the port offers various ship maintenance and repair services. It also provides fishing-related operations: it serves the fishing industry by offering docking as well as processing facilities to fish catches.

Operation and Management of the Port

• The port is managed by a professional team responsible for all aspects of the port operations, from berthing arrangements for ships, coordination in cargo handling processes (like stevedoring activities), up to ensuring safety and security within the port area.
• This involves close coordination with shipping lines, customs, and local carriage providers. The management is also concerned with the constant upgrading of the facilities and services in the port to meet changing demands within the shipping sector.

Port Facilities

• The following are the major features of this port: equipped with a full range of facilities, having a number of berths of varying depths and lengths to handle various vessels. Advanced cargo - handling equipment, such as cranes of various capacities and forklifts, help in efficient transfer of goods from and to ships and land-based transportation.
• There are also storage facilities for different types of cargo. These include warehouses for general cargo and silos for bulk materials like grains. Added to this is the facility of ship refueling and maintenance, including a dry - dock and repair workshops.

Channel and Direct Navigation

• The port has a well-maintained channel that allows ships to enter and leave safely. The channel is dredged periodically to keep the correct depth for vessels with various drafts. The navigational aids in place include buoys, lighthouses, and modern radar systems to guide the ships during their approach and departure. This way, direct navigation is allowed to vessels coming from various directions in the Baltic Sea.

2. Importance of Measuring Ocean Currents in Rohuküla Port

Navigation Safety

• The measurement of ocean currents in Rohuküla Port is important from the point of view of ship safety. Currents in the Baltic Sea may be complicated and difficult to forecast. Knowledge of these currents helps ship captains and navigators to plan their routes more accurately.
• For example, strong or unexpected currents can make a ship drift out of course. With knowledge of the currents, a vessel may alter its speed and direction to prevent collision with other vessels or grounding, while performing certain maneuvers such as docking and undocking.

Efficient Port Operations

• Understanding the ocean currents is beneficial for the efficient operation of the port. By knowing the current patterns, port authorities can better schedule ship arrivals and departures. Ships can take advantage of favorable currents to reduce fuel consumption during docking and undocking procedures.
• This also helps in optimizing the use of port resources. For instance, if the current is flowing in a direction that aids the movement of ships to or from a particular berth, the time required for these operations can be significantly reduced, leading to more efficient use of the berths and other port facilities.

Environmental Protection

• Currents play an important role in the dissemination of pollutants within the port area. In the event of oil spills or other types of chemical releases, an understanding of the current patterns becomes a necessary prelude to efficient containment and clean-up operations. The port can also manage better the discharge of wastewater and other substances by monitoring the currents in order to minimize their effect on the marine environment. This is particularly important as the port falls within a sensitive marine ecosystem.

Infrastructure Maintenance

• Long-term forces exerted by ocean currents on the structural integrity of breakwaters and quay walls are considerable. Measurement will provide the port engineers with data to predict and avoid possible damages to such structures.
• ADCP (Acoustic Doppler Current Profiler) provides a more advanced and convenient way to measure ocean currents compared to traditional methods. It offers detailed and real - time information about current profiles at different depths, which is crucial for the long - term planning and maintenance of port infrastructure.

3. How ADCPs Using the Doppler Principle Work

Basically, the operations of ADCPs are based on the Doppler principle. They send acoustic signals down into the water. Such acoustic waves interact with movable particles in water-sediment, plankton, or just some other small organisms moved by the ocean current. When those waves bounce back, the frequency of reflected waves changes.

This frequency shift, called a Doppler shift, varies directly with the velocity of these moving particles and thus of the ocean current. Various transducers of an ADCP current meter emit and receive these acoustic signals in different directions. Thus, by measuring the Doppler shift from multiple directions-the usual three-dimensional or two-dimensional configuration-the ADCP current profiler determines the speed and direction of the ocean current at all different depths.

ADCP in Port Ocean Current Measurement

Shipborne ADCP

• Shipborne ADCPs are mounted on ships. While the ship is underway in the water, the ADCP flow meter sends acoustic signals continuously downward and around. It gathers information about the current velocity as the ship travels over different areas of the port.
• The advantage of the method is its mobility. It can perform a wide range of measurements within the port waters. However, for the accurate results, the ship's own motion should be taken into consideration. Calibration and compensation methods are used to remove the errors caused by the ship's movement.

Fixed ADCP

• Fixed ADCPs are deployed in specific locations in the port either at the seabed or from fixed structures like piers or buoys. They continuously monitor the ocean current at that fixed point over an extended period.
• This provides long-term and consistent data for understanding the regular current patterns in a specific area of the port. The disadvantage is that they only cover a limited area around their installation location, but they are very useful for establishing reference current data for particular regions within the port.

4. Requirements for High-Quality Measurement of Currents in Rohuküla Port

Equipment Materials

• The equipment materials should be of high quality to measure the ocean currents in the Port of Rohuküla. Because seawater is corrosive and floating debris may cause impacts, a durable material is needed.
• The equipment should be designed to withstand the marine environment of the Baltic Sea and not be degraded in performance over time. ADCPs can be mounted in a casing of titanium alloy, which offers excellent corrosion resistance in seawater.

Compact and Lightweight Design

• The size of the equipment should be small for easy installation, especially in space-restricted areas such as on small buoys or in regions with complex underwater structures.
• A lightweight design is also advantageous as it will simplify the installation and maintenance processes. This is quite significant for equipment that could be deployed and retrieved frequently.

Low Power Consumption

• Low power consumption is essential, particularly for long-term monitoring. Equipment with high power requirements may not be able to operate continuously due to limited power supply options in the port area or because frequent replacement of batteries will be required.
• This is especially relevant for fixed ADCPs that are expected to operate continuously for extended periods.

Cost-Effectiveness

• Cost-effectiveness is also a factor. For comprehensive current measurement in the port, affordable equipment allows for more extensive deployment, enabling a more thorough understanding of the current conditions throughout the port waters.
• This is important for a port like Rohuküla to optimize its resources and make informed decisions about current measurement strategies.

5. How to Choose the Right Equipment for Current Measurement

Based on Usage Purpose

• Shipborne ADCP: In the case where one wants to collect current data over a wide area of the port while the ship is in operation-for example, during regular port surveys or when collecting data for navigational chart updates-the use of shipborne ADCPs is appropriate. They can cover different parts of the port as the ship moves around.
• Bottom-mounted (Sitting) ADCP: In cases where the monitoring of specific locations within the port needs to be done for a longer period and in a fixed-point manner, such as near critical infrastructure like breakwaters or at the entrance of the port channel, bottom-mounted ADCPs are suitable. They provide stable and continuous data for understanding the local current characteristics.
• Buoy-mounted ADCP: In cases where seabed and structure installations for fixed equipment are not at all convenient, or for floating monitoring points to capture conditions of currents at the surface or near the surface, a buoy-mounted ADCP applies.

Based on Different Frequencies

For water depths within 70 m, a 600-kHz ADCP is usually the better option. It would have a higher resolution in shallow areas and therefore provide an acceptable current profile in those areas not of very deep water, which can apply to a majority of the parts within a port, especially the ones closer to quay walls or even the inner harbor area.

• When dealing with water depths up to 110m, a 300kHz ADCP is more appropriate. It can effectively penetrate the water column at these depths and accurately measure the current velocities.
• For deeper areas, like in the approach channel of the port where the water depth may be more than 1000m, a 75kHz ADCP is recommended. Its lower frequency allows it to reach greater depths and still obtain useful current information.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. For cost-effectiveness and high quality, it would be worth considering a China Sonar PandaADCP. The body is made from all-titanium alloy material, durable yet with very good performance. With such an excellent cost-performance ratio, this would be the right choice for ocean current measurements in the Port of Rohuküla. You can learn more about it on its official website: (https://china-sonar.com/).

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