ADCP's Application to Ocean Current Measurement in Aalborg Port

1. Where does Aalborg Port Locate?

Aalborg Port is located in Aalborg, one of the big cities in northern Jutland, Denmark. Geographically, it is on the Limfjord, which gives a sheltered and negotiable waterway branch connecting to the North Sea. This strategic location has made it a significant maritime hub in the region.

Port Scale and Throughput

Aalborg Port is one of the largest ports in Denmark. It has an impressive annual throughput, given that it handles a wide range of diversified cargo. Generally, on general cargo, the port handles everything from building materials through to consumer goods. The port also has an impressive bulk cargo volume: grain, coal, and minerals are just some of the items. Every year, it serves a large number of vessels from both the domestic and international markets, which are contributing towards the economic growth of Aalborg and its surrounding areas.

Routes and Business The port has well-established ferry routes. Not only does it connect to several other Danish ports, such as Copenhagen and Frederikshavn, but also international routes to the ports of Norway, Sweden, and Germany. The ferry services appear indispensible for transportation in passengers as well as in freight. In addition to the ferry services, Aalborg Port is also heavily engaged in container shipping, handling a significant volume of containerized cargoes. It also serves as a base for fishing vessels, supporting the local fishing industry.

Management and Operation of the Port

Aalborg Port is managed by a professional port authority which operates the facility very efficiently. The management undertakes the maintenance of berths, quays and storage facilities of the port. It also takes care of safety concern and environmental standards, international shipping norms. The port authorities liaise closely with the shipping companies, freight forwarders, and other agents in the interest of simplifying operations and making the port more competitive.

Facilities of the Port

It boasts of modern facilities that enable it to handle different cargo and vessel types. Several berths with varying lengths and draft capabilities constitute the port, thus enabling it to berth large-scale container ships, bulk carriers, and passenger ferries. Advanced cargo-handling equipment includes gantry cranes, reach stackers, and forklifts, which are provided to ensure speed and efficiency in the loading and unloading of goods. Besides, Aalborg Port has also extended storage facilities, general cargo warehouses, and open-air storages for bulk commodities.

Waterways and Direct Navigation

The fairways to Aalborg Port are well maintained. Limfjord provides a reasonably quiet and navigable channel, though the tides and shallow water require careful navigation. The port enjoys direct navigational links with all major Scandinavic and northern European ports, hence ensuring smooth goods and passenger transit. Regular dredging is undertaken to keep the channels deep enough for big vessels to access the port.

2. Why is it necessary to measure ocean currents in Aalborg Port?

Navigation Safety

Correct knowledge of ocean currents at Aalborg Port is first and foremost important for navigation safety. Limfjord has a very complex topography combined with tidal movements, which creates variable current conditions. Currents will provide a resistance force on vessels that will affect their speed and direction, and it is important that the updated information should be with the ship captain. By measuring ocean currents, one can plan a route more accurately, adjust one's speed appropriately, and be able to circumvent potential collision or grounding of ships.

Optimizing Port Operations

Currents are especially useful in optimally operating certain aspects of a port. The direction and speed of the flow of water come into play as vessels berth and unberth. A strong current can make the process more difficult; thus, having accurate current measurements allows the port operator to choose the most appropriate time and manner for vessel maneuvering. Currents also affect the way floating cranes and other port-related equipment are moved around, and they help improve the efficiency of cargo handling operations.

Protection of the Environment

The measurement of currents is very important for environmental protection in the port area. The currents are a major factor in the dispersion of pollutants. If oil or other harmful liquids have been discharged, information on current conditions may enable the flow of such pollutants to be forecast. In this respect, the facility enables environmental managers to take prophylactic and cleaning actions in due time, which protect the sensitive marine ecosystem of Limfjord and the coasts from destruction.

In the perspective of these prerequisites, ADCP profiler has become widely used and increasingly effective in providing high-precision and real-time data collection, hence a potent tool in ocean current measurement within Aalborg Port.

3. Measurement Principle: The Doppler Principle

ADCPs work through the principle called the Doppler effect. The acoustic signals, when an ADCP meter sends them into the water column, go through the water, which contains a lot of suspended particles such as sediment, plankton, or small organisms that are carried along with the water current. Consequently, the frequency of the sound waves reflected back to the ADCP is different from the original frequency transmitted. This frequency shift, now called the Doppler shift, is measured. Application of the Doppler equation will finally enable the instrument to calculate, from that measured frequency shift, the velocity of the water current at discrete pieces of the water column.

Specific Methods in Port Current Measurement

• Ship-borne ADCP: A shipborne ADCP has been installed in a moving ship. When that ship navigates through the water in Aalborg Port, for example, the ADCP flow meter is able to measure current at several depths out along the path of the moving ship. It offers a good possibility to get the broad-scale view of the instantaneous conditions in the port. It can be applied, for example, to delineate the characteristic current patterns within the various sections of the port, which might be useful when planning large-scale navigation and flow characteristics of Limfjord water.
• Fixed ADCP: These are installed in fixed locations at the port either on the seafloor or on fixed structures such as piers or buoys. These ADCPs can monitor conditions of currents continuously at a specific point for extended periods. That will be of value for long-term trends as well as the local variations at places like near the berths, in narrow channels, and at critical points of navigation at Aalborg Port.

4. What's needed to have high-quality measurement of the currents in Aalborg Port?

Equipment reliability

The ADCP equipment for high-quality current measurement in Aalborg Port has to be highly reliable. The marine environment of the Limfjord, with its exposure to saltwater, changing weather conditions, and potential mechanical stress, demands that the ADCP is able to resist these influences without frequent breakdowns. Reliable equipment means consistent data collection, which is very important for accurate analysis and decision-making.

Size, Weight, and Power Consumption

First of all, an ADCP current profiler must be compact and lightweight.

Such a design promotes ease of installation, especially with the lack of space on some small fishing vessels or in close port structures, for example.

The low consumption of power ensures long-term capability of operation, considering that fixed-in-place ADCPs are often on battery-powered systems or solar panel systems. In the case of Aalborg Port, where continuous monitoring is often required, low - power - consuming ADCPs can operate for extended periods without the need for frequent recharging or power source replacements.

Cost-effectiveness

The ADCP should be reasonably priced to enable large-scale measurement in the port area. A reasonable price for an ADCP allows multiple units to be deployed if necessary, in order to get comprehensive current data from different parts of the port. This is important for getting a complete picture of the current conditions in Aalborg Port, which can help in various applications, from navigation safety to environmental protection.

Material Selection

The ADCP current meter enclosure shall be of titanium alloy. The main advantage of the titanium alloy is excellent corrosion resistance, which will provide long service life in the saline environment of Aalborg Port. It will provide good resistance against saltwater corrosion for a longer period and make the ADCP durable. Titanium alloy is strong yet lightweight, thus fulfilling both the structural strength and ease of installation criteria.

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

Based on Usage

• Ship-borne ADCP: It is best used in large-scale surveys of the port area. When a ship needs to make a wide ranging estimate of the current conditions in fairly quick time, ship-borne ADCP is the best option. In Aalborg Harbor, it is possible for more significant vessels-container ships or ferries-to gain information while they move through the port and in real-time present data on the current conditions along their route.
• SIT-ON-BOTTOM ADCP: The instrument is suited for long-term monitoring of the specific location of the port, for example near the entrance where the current could have a crucial impact on the navigation, in a channel where the current has a significant effect on navigation or close to the berth where the current affects the vessel berthing operations. In this case, a sit-on-bottom ADCP can be laid on the seabed for continuous recording of current data.
• Buoy-mounted ADCP: Very useful in shallow water and when fixed-bottom installation is not possible. In the Limfjord, this would be specifically for areas where there could be strong tidal currents, or indeed where it would be inappropriate to install bottom-mounted ADCPs due to general bed conditions. A buoy-mounted ADCP can be deployed that will be able to move with the flow of the water while providing data regarding surface-layer currents. Based on Frequency
• For water depths within 70m, an ADCP with a frequency of 600kHz will be sufficient. At Aalborg Port, large areas-especially near the shores and some of the inner-port channels - have water depths within this range. A 600kHz ADCP will be able to give high-resolution data in these shallow water areas, resulting in very detailed analysis of the current conditions.
• A 300kHz ADCP can be applied to water depths up to 110m, which means it can act in areas where there is a moderate depth at the port-for example, within some of the main shipping channels where the depth isn't really deep but needs precision current measurement.

When dealing with deeper water areas in Aalborg Port or in the adjacent Limfjord, such as the outer parts of the port, with higher depths, a 75kHz ADCP will be what it takes. This frequency is suitable for measuring currents in water with up to 1000m depth.

Of them all, a few well-known ADCP brands include Teledyne RDI, Nortek, and Sontek. However, for those who want something in a more reasonable price but with no compromise in quality, they will highly recommend the Chinese brand China Sonar PandaADCP. The material is all from titanium alloy, and thus can maintain very good durability in marine environments. Besides, it could achieve an incredibly good cost-to-performance ratio.

You can visit their website at https://china-sonar.com/ for more information.

Here is a table with some well known Acoustic Doppler Current Profiler(ADCP)  instrument brands and models.