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

1. Where is Eleusis Port?

Overview of Eleusis Port

Eleusis Port is located in Greece. The port has a rich history and has a vital role in local and regional maritime activity. The scale and throughput are moderate. The different range of functions comprises handling industrial goods, such as mainly chemicals and construction materials, with some agricultural products.

The port is well-connected to the surrounding transportation network, allowing for the efficient distribution of goods to inland areas. The management of Eleusis Port focuses on safety and operational efficiency. There are teams dedicated to vessel traffic management, cargo handling, and infrastructure upkeep to ensure smooth operations.

Port Facilities

Berths: The port has various berths built for the reception of vessels of different natures. These include berths for medium-sized cargo ships and barges. Modern mooring and docking facilities have been installed to guarantee safe arrival and departure of ships. The fenders and bollards provide protection to the ships and berths during docking and undocking.

Cargo-handling Equipment: There is a range of cargo-handling equipment along the quay. For bulk materials that include chemicals and construction materials, there are conveyor systems with specialized handling equipment. There are forklifts and cranes for general cargo and agricultural products to move goods between the ships and the storage areas.

Storage Facilities: Storage facilities are available for various cargo types. Chemicals are stored in secure storage tanks and warehouses, with proper safety precautions applied. Construction materials and agricultural produce are stored in stockpiles and warehouses under appropriate storage conditions.

Channel and Navigation Aids: The channel of the port is dredged to sufficient depth and breadth for safe passage navigation. Regular dredging operations are carried out to keep it navigable for vessels with different drafts. Navigation aids include buoys, beacons, and radar systems that help guide ships into and out of the port. The radar systems provide real - time information about the position and movement of other vessels in the vicinity of the port.

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

Importance for Port Operation and Management

In Eleusis Port, measuring ocean currents is particularly important. First and foremost, due to vessel safety concerns: knowledge of current speed and direction is important for the master of a ship during a berth approach or when a vessel is navigating the channel. A strong cross-current near a berth can make the process of docking quite difficult and even dangerous. For example, a ship approaching a berth against a strong current may need to adjust its speed and angle of approach to ensure smooth and safe docking. Precise current measurements enable captains to make informed decisions and reduce the risk of collisions and other accidents.

It is also crucial for the optimization of the port's operations: Current data aids in efficiently scheduling the arrival and departure of ships. By comprehending the tidal currents and other normal patterns of flow, the port authorities can better manage the allocation of berthing resources and planning of loading and unloading activities. Productivity thereby increases as cargo-handling operations can be coordinated more effectively.

In addition, from an ecological point of view, when it comes to the occurrence of a spill of hazardous products, such as chemicals, ocean currents knowledge is priceless. As the port handles highly risky cargo, the forecast of any eventual spill is of much help. The current data may immediately be used to embark upon containment and mitigation actions for minimizing environmental damage.

Compared to conventional techniques, ADCPs offer a far more precise and practical solution for measuring these currents.

3. How do Doppler Principle-based ADCPs work?

Measurement Principle

ADCPs work on the principle of the Doppler effect. When an acoustic signal is transmitted by the ADCP flow meter into the water, the moving water particles interact with it. Due to the presence of an ocean current, the water particles are in motion and hence cause a frequency shift in the reflected acoustic signal received back by the ADCP meter. This frequency shift, by the Doppler effect, is proportional to the velocity of the water 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 transmitting signals at multiple angles, and at different depths, a profile of the ocean current is achieved, showing variations of the current with depth.

ADCP Deployment in the Port

Shipborne ADCP

A shipborne ADCP is installed on ships operating in the Eleusis Port area. As the ship moves around the port, the ADCP profiler continuously emits acoustic signals into the water below. The ship's movement allows the ADCP flow meter to cover a wide area and collect current data from different locations. For instance, in a normal survey of the port by a research or inspection ship with a shipborne ADCP, it is able to collect data from the current patterns across different parts of the port and provide a comprehensive understanding of the water flow situation.

Fixed ADCP

Fixed ADCPs are deployed at fixed locations in the port, like on the seabed in the area with important navigation or at the port's entrance/exit. These continuously record the ocean currents at their fixed positions over long periods. The data is used for evaluating regular current patterns in specific areas of the port. For example, a bottom-moored ADCP installed near the entrance of the port can measure the currents entering and leaving the port, which will help in understanding the tidal effects and other consistent flow characteristics of that area.

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

Equipment Requirements

In order to measure the currents in Eleusis port in high quality, some equipment characteristics are of paramount importance. First of all, the reliability of the materials is the most important one. The equipment has to bear the aggressiveness of the marine environment. Seawater contains salts and other chemicals that destroy the material over time. The equipment also has to resist the pressure changes for different water depth and the mechanical forces of waves and currents.

It would be preferred to be of a smaller size, lighter in weight, and with lower power consumption. A compact size makes installation in various locations in the port easier, whether on ships, fixed structures such as piers, or even on the seabed. A lighter weight will ease the processes of installation and transportation. The use of low power ensures that the equipment can work without problems for extended periods without necessarily having to replace batteries now and then or the need for very high power supplies, especially in applications that require long-term monitoring.

Cost is another major aspect. A low-cost solution allows the port to install a higher number of measuring devices for extensive current monitoring at different places of the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferred to be made from titanium alloy. Titanium alloy has excellent corrosion resistance, meaning it can stand and function even when submerged in seawater for quite a long period of time. Its high strength-to-weight ratio allows a durable yet relatively lightweight casing to be constructed. For instance, in those parts of the Eleusis port which are pretty deeper and have higher water pressures, the ADCP current meter with its casing made of titanium alloy can support these pressures without failing, even while providing accurate current measurements.

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

Selection Based on Usage

Shipborne ADCP: Shipborne ADCP would be most adequate to suit the purpose of making widespread surveys of the waters for which the port caters, while in operation. A vessel could cover areas from its movements around different parts of a port and gather numerous measurements across the entire length in view for a general view of currents within the area at question. This can be useful for mapping general patterns of flow and variations across different areas of the port waters.

Sitting-bottom ADCP: For long-term and fixed-point monitoring of certain places in the port, such as near important infrastructures or areas with complex current behaviors, sitting-bottom ADCPs are more appropriate. They can continuously record the current data at those fixed positions, providing valuable insights into the local current characteristics and any changes over time.

Buoy-mounted ADCP: In the case where it is not convenient to install fixed equipment on either the seabed or a ship, buoy-mounted ADCPs have been used. They are floating on the water surface and, therefore, are able to measure the currents of the higher layers of the water column. Relatively easy to deploy and re-deployable if necessary, they are suitable for monitoring dynamic or hard-to-reach areas within a port.

Selection Based on Frequency

The choice of frequency for ADCPs depends on the water depth in Eleusis port. In areas with a water depth of up to 70 meters, an ADCP current profiler with a frequency of 600 kHz is generally a good choice, as it can provide current measurements quite accurately in this relatively shallow depth range. On sites with deeper waters, averaging approximately 110 m deep, a 300-kHz-type frequency ADCP would be recommended; for those extremely deep portions where bottom clearance already attained up to 1000 m, the recommended type and accuracy requirement would be a 75 kHz ADCP for efficient profiling of ocean currents of that depth.

There are several well - known ADCP 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.