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

1. Introduction to the Port of Arklow

The Port of Arklow is situated on the east coast of Ireland. It is a well-established port with a long history of maritime activities.

Port Scale and Throughput

• The port is of relatively small to medium size. Its throughput mainly consists of a variety of cargo, including building materials, agricultural products, and some industrial goods. It also serves as a base for fishing vessels. The infrastructure of the port is so developed to bear the flow of goods and to provide the possibility to dock different types of ships, from small fishing boats up to medium-sized cargo vessels.
• The port contains several berths of varying depths and lengths to cater to the different vessels utilizing it. The capacity of the port is such that it can handle a good, constant flow of traffic, though not as great as some of the larger international ports.

Routes and Business

• Domestically, it is well connected to other Irish ports to facilitate the distribution of goods inland. Internationally, it has connections with the UK and other European countries mainly for trade in local products such as aggregates and agricultural produce.
• The major activities in business include cargo handling, fishing, and light manufacturing activities linked to the operation of the port. The port has facilities for loading and unloading cargo, with storage areas where goods are stored before further movement.

Management and Operation of the Port

• The port is managed by a team of professionals who oversee all aspects of its operation. This includes the organization of berthing for ships, the coordination of cargo handling, and the maintenance of safety and security standards.
• Management also works hand in hand with locals who offer such services like fishermen, businesses, as well as providers of transportation facilities. This involves the dredging of the port channel as well as performing any other functions that maintain port facilities in proper functioning state.

Port Facilities

• It is equipped with basic to intermediate - level port facilities. There are berths with appropriate depths for different types of vessels. The port has cargo - handling equipment such as cranes and forklifts to assist in the transfer of goods.
• Storage facilities for various types of cargo, including building materials and perishable agricultural products. The port also has refueling facilities for ships and basic maintenance facilities.

Channel and Direct Navigation

• The port has a maintained channel where ships can enter and leave safely. The channel is dredged periodically to maintain the depth for ships with various drafts. Navigation aids include buoys and lights that show the way to ships on approach and departure. This will enable direct navigation for vessels coming from different directions along the Irish Sea.

2. Importance of Measuring Ocean Currents in Arklow Port

Navigation Safety

• Measuring ocean currents in the Port of Arklow is important for safety reasons. The Irish Sea has areas with strong, unpredictable current patterns. Such knowledge enables ships to navigate more safely, especially during the operations of docking and undocking.
• For instance, if at all a ship is not informed about a strong cross current, it might be forced off-course and could collide into other vessels or run onshore. With proper currents information, masters of such vessels can take corrective measure on speed and course to keep away from such accidents.

Efficient Port Operations

• The understanding of ocean currents serves the port in the best manner. By understanding 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.
• This also aids in the optimization of port resources. For example, if the current is flowing in a direction to assist the movement of ships to a particular berth, the process of loading and unloading can be carried out in a much more efficient manner.

Environmental Protection

• Currents play an important role in the dispersal of pollutants within the port area. In cases of oil spills or any other type of chemical leakage, it becomes imperative to have adequate knowledge about current patterns so that proper containment and clean-up measures can be resorted to.
• Similarly, the discharge of wastewater and other materials from the port can be managed better if the current patterns are considered with a view to minimize their adverse impacts on the marine environment.

Infrastructure Maintenance

• The forces of currents over time can come to affect the structural integrity of port infrastructures, such as breakwaters and quay walls. Measurement of currents therefore provides useful data in view of long-term planning and maintenance of such structures.
• For instance, if the currents are strong in a particular area, additional reinforcement may be necessary to prevent erosion and damage to the quay walls. Acoustic Doppler Current Profiler (ADCP) is a more advanced and convenient way of measuring ocean currents compared to traditional methods.

3. How ADCPs Using the Doppler Principle Work

ADCPs are based on the principle of the Doppler effect. They send acoustic signals into the water. These acoustic waves scatter off moving particles in the water, such as sediment, plankton, or other small organisms moving with the ocean current. When these waves return, or scatter, the frequency of the reflected waves has changed.

This frequency shift, called the Doppler shift, is linearly proportional to the velocity of the moving particles and hence the velocity of the current. ADCPs use several transducers to transmit and receive these acoustic signals in various directions. The Doppler shift, when measured from multiple directions-as was done in this case in three - or two - dimensional setup-allows the ADCP meter to compute the current velocity magnitude and direction at a number of depths.

ADCP in Port Ocean Current Measurement

Shipborne ADCP  

In shipborne ADCPs, the units are installed on ships. The ship travels in the water while the ADCP profiler continuously sends acoustic signals downward and around. It monitors the current velocity as it travels over different areas of the port. The advantage of this is its mobility. That it can give a wide range of measurement within the waters of the port. It has to account for its own motion of the ship to get accurate results. Calibration and compensation methods correct the errors caused due to the movement of the ship.

Fixed ADCP

Fixed ADCPs are set up in specific locations in the port, such as on the seabed or on fixed structures like piers or buoys. They can continuously monitor the ocean current at that fixed point over an extended period.

This therefore means that long-term and sustained information about the normal current phenomena within a given area in the port is obtained from these devices. The shortfall is that they cover an area just around their point of installation, though they are also very handy in establishing reference current information for specific locations within the port.

4. Requirements for High Quality Measurement of Currents in Arklow Port

Equipment Materials

The equipment materials need to be reliable for the high-quality measurement of the ocean currents in the Port of Arklow. Due to the salinity of the seawater and possible floating debris that may cause an impact, a durable material must be used.

The equipment has to be designed to be survivable in the marine environment of the Irish Sea and perform with consistency. The casing of ADCPs could be made from Titanium alloy since it has superior resistance to corrosion in seawater.

Compact and Lightweight Design

• The size of the equipment should be small to facilitate easy installation, especially in areas with limited space such as on small buoys or in regions with complex underwater structures.
• A lightweight design is also beneficial as it simplifies the installation and maintenance processes. This is particularly important for equipment that may need to be deployed and retrieved frequently.

Low Power Consumption

• Low power consumption is necessary, especially for long - term monitoring. Equipment with high power requirements may face difficulties in maintaining continuous operation since power supply options in the port area are limited or frequent battery replacements are required.
• This is of particular relevance to fixed ADCPs intended for continuous use over an extended period.

Cost - Effectiveness

• Cost-effectiveness is also relevant. The availability of economic equipment makes it possible for a wide deployment for more comprehensive current measurement in the port waters.
• Being such a port, optimizing resources by Arklow for the most appropriate decisions is key for current measurement methodologies.

5. How to Choose the Right Equipment for Current Measurement

Based on Usage Purpose

• Shipborne ADCP: If the objective is to acquire current data over a large area of the port while the ship is in operation, for example, during regular port surveys or when collecting data for navigational chart updates, shipborne ADCPs are suitable. They can cover different parts of the port as the ship moves around.
• Bottom - mounted (Sitting) ADCP: When long - term and fixed - point monitoring of specific locations within the port is required, 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: When for one reason or another the installation of fixed equipment either on the seabed or on structures is not appropriate, and a floating monitoring point is wanted to catch the current conditions on the surface or near surface, then it's a buoy-mounted ADCPs job.

Based on Different Frequencies

• For water depths within 70m, a 600kHz ADCP is often a good option. It can provide a relatively high-resolution current profile in shallower areas, which is suitable for most parts of the port not having extremely deep water, such as near the quay walls or inner harbor.
• For water depths of up to 110m, a 300kHz ADCP would be more appropriate; this would effectively penetrate the water column at such a depth and measure the current velocities accurately.
• In much deeper areas, say for the approach channel in the port that may go up to depths of 1000 meters, one could consider employing a 75kHz ADCP. It's much lower in frequency but has the propensity to give depth penetration. This yields an increased measurement depth range for obtaining beneficial current data.

There is a quite renowned brand-Teledyne RDI, Nortek and Sontek. However, for those who are in need of a cost-effective option with excellent quality, China Sonar PandaADCP would be a good alternative. It is made from all-titanium alloy material that combines durability and good performance. With its incredible cost-performance ratio, it is an excellent choice for ocean current measurement in the Port of Arklow. You can learn more about it from its official website: (https://china-sonar.com/).

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