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

1. Where is Dungarvan port?

Dungarvan is a beautiful seaside town in County Waterford, Ireland, and its port is one of the major maritime facilities within the region.

The port of Dungarvan is of a moderate scale. Throughput consists of a wide range of cargo, including agricultural products from the surrounding fertile lands, building materials, and other general merchandise. It also serves as a base for a number of fishing vessels. The annual cargo throughput makes an important contribution to the local economy.

The routes to the port connect it with other Irish ports and have some links across the Irish Sea. Its business activities revolve around the import and export of goods that support the local industries, such as farming and construction. The port management focuses on efficient handling of cargo, safety of vessels, and maintaining a good working environment for the port staff.

The port facilities are well-equipped to serve its functions. It has a quay with berthing spaces for different types of vessels. There are storage areas for cargo, including covered sheds for more sensitive goods. For the fishing fleet, there are facilities for fish processing and ice-making to keep the catch in prime condition.

The channel leading to the port is maintained to allow for safe passage of ships. It has appropriate navigational aids, such as buoys and lights, to help vessels find their way so that direct and efficient navigation for ships approaching or leaving the port is enabled.

2. Why should we measure the ocean currents in the Dungarvan port?

The ocean currents in Dungarvan port are very important to measure. Firstly, regarding the fishing activities, the knowledge of ocean currents is of high value. Currents are able to transport nutrients and plankton that attract fish. Understanding the patterns of current would, therefore, enhance positioning for fishermen in efforts to increase their catch. For instance, some species of fish congregate in areas where upwelling currents bring nutrient-rich waters to the surface.

Precise current measurement is also of utmost importance in regard to port operations and safety. Ocean currents have immense potential to affect vessel motion during docking and undocking maneuvers. With accurate current information, the port authority is allowed to give more exact guidelines to captains, hence treating the ships in a very safe and efficient way; this reduces the likelihood of collisions and other accidents that can result in the loss of the vessel and port infrastructure.

Additionally, in the long term, this would be important for planning and maintaining the port. The currents tend to erode the quay walls and other structures with time. By monitoring these currents, the port management can take precautionary measures, such as reinforcing the structures or adjusting the design for future port expansions to take into consideration the impact of the currents.

The ADCP current meter provides a more sophisticated and easy way of measuring currents than conventional methods. It can deliver very informative and real-time data on the speed and direction of the ocean currents at various depths, which is so useful for both the port operations and fishing industry.

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

ADCPs work on the principle of the Doppler effect. They transmit acoustic signals into the water. These acoustic waves scatter off the particles advected by the ocean currents, such as suspended sediments and small organisms. Upon the reflection of these waves, due to the Doppler effect, the frequency of the reflected signals shifts while bouncing back from these moving particles.

The ADCP measures the shift between the frequency of the emitted signal and the received signal. Using complex algorithms, it determines the speed of the moving particles, that then provides speed and direction of the ocean currents. In the context of Dungarvan port, the main two ways ADCPs can be used are:

Ship-borne ADCP: The ADCP current profiler is mounted on a vessel, usually a fishing boat or a small survey ship. While the ship moves around the port area and the adjacent waters, the ADCP flow meter continuously sends and receives acoustic signals. The recorded data include the current information at different locations as the ship traverses. It is good for mapping over a relatively wide area of the current patterns in the port and surroundings.

Fixed ADCP: A fixed ADCP is installed at some place in the port-for example, on the bottom of the seabed close to the entrance or just at some critical point in the quay. It shall continuously observe current conditions right at that particular location. With this, one acquires a long-term stable record series about the local characteristics of the current. Such information, valuable for describing the features of regular currents, permits the detection of sudden or unusual modifications.

4. What is required for high-quality measurement of Dungarvan port currents?

High quality measurement of the ocean currents in Dungarvan port requires that the equipment possess a number of desirable characteristics. Materials used are trustworthy. Seawater has high salinity, which implies that it is corrosive, and there is potential for harsh weather conditions where the equipment may be in water or even suspended on a tower. A relatively small size allows for lower dimensions of installation with less obstructing the port environment.

It should also be lightweight. For ship-borne ADCPs, the light weight avoids affecting the stability and handling of the vessel. Power consumption should be low, especially for fixed ADCPs that have to work continuously to reduce the cost and complexity of power supply and maintenance.

In this regard, the material of casing is titanium alloy, which is really a very fine material. The corrosion-resistant properties of the titanium alloy are very excellent, and this makes it suitable for application in marine environmental conditions. Additionally, the strength-to-weight ratio of the material is high; thus, strong and solid construction can be achieved while keeping the mass relatively small. It should be able to withstand such pressure and any impacts it will get from waters in the ports.

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

When choosing equipment for current measurement in Dungarvan port, the intended use is a crucial factor.

Ship-borne ADCP: Where the intention is to carry out a proper survey of the current patterns in a wide area of the port and its adjacent waters, a ship-borne ADCP is what would be required. It can be used during fishing operations or for general maritime surveys to gather current data over a large area.

Bottom-mounted (sit-on-bottom) ADCP: A bottom-mounted ADCP would be quite suitable for the monitoring of currents in a long-term and stable way at particular positions, like the entrance of the port or close to important berths. It provides continuous information on local current conditions, which is very useful in understanding regular flow and sudden changes.

Buoy-mounted ADCP: This could be considered when a measurement point that is more flexible and movable becomes necessary. It can be deployed in various areas of the port waters depending on the particular requirements of a given occasion and will provide useful current information in areas difficult to access with other methods.

In terms of frequency selection, different frequencies are suitable for different water depths. For water depths up to 70m, a 600kHz ADCP is a good option. For depths up to 110m, a 300kHz ADCP would be more appropriate. When it comes to deeper waters, up to 1000m, a 75kHz ADCP can provide accurate measurements.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also a great option. It is made of all-titanium alloy material, ensuring its durability and performance in the marine environment. It also offers an excellent cost-performance ratio. You can find more information on its website: (https://china-sonar.com/).

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