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

1. Location of Larymna Port

Overview of Larymna Port

The port is a coastal one located in the country of Greece. A relatively small to medium-sized port with moderate throughput in and out. It represents local and regional maritime-related activities like fishing, transport of local agricultural produce, as well as some light industrial goods transported by sea.

It is well-integrated into the local transport structure, enabling the efficient distribution of loads to outlying regions with ease. The management team of the Larymna Port ensures a normal flow of activities and security of ships and cargo. There are units responsible for vessel traffic management, cargo handling, and infrastructure maintenance among others.

Facilities

Berths: It has a considerable number of berths planned to manage various types of vessels. There are berths for small- to medium-sized fishing boats and cargo ships. The facilities include very basic mooring and docking so that the arrival and departure of ships can be safely done. Bollards and fenders have been used to protect the ships and the berths from any type of damage while doing or undoing the docking.

Cargo Handling Equipment: At quay level, a variety of different cargo-handling equipment should exist. For fishing vessels: unloading equipment such as cranes and conveyor belts to handle fish and all allied marine products. For the General cargo : to move cargo between ships and storage areas, forklifts and small cranes could be available.

Storage Facilities: There are storage areas for different types of cargo. For perishable goods like fish and agricultural products, cold - storage and well-ventilated warehouses are available. For other general cargo, there are storage sheds and container yards.

Channel and Navigation Aids: The channel at the port is kept at an adequate draft and width to take vessels safely through it. A set of buoys, beacons, and a very simple radar system at the head of the harbor ensure ships get into or out of the port in one piece. This system at the radar gives the standard position of the vessel plus some details about other vessels situated in its neighborhood.

2. Why measure ocean currents in Larymna Port?

Importance for Port Operation and Management

The measurement of ocean currents in Larymna Port is of paramount importance. First of all, it is very important for vessel navigation safety. The knowledge of the speed and direction of the current is crucial for the captains while approaching the berths or passing through the channel. A cross-current near a berth can make the process of docking tricky and hazardous. For instance, if a ship is approaching a berth against a significant current, he might have to adjust the speed and angle of approach to ensure smooth and safe docking. Precise current measurement helps captains make informed decisions and minimize the risk of collision and accidents.

It is also vital for the optimization of the port's activities. Real-time data can enable good planning in the arrival and departure of ships. With knowledge of tidal currents and other cyclic flow conditions, port authorities are able to better plan berthing resources and loading and unloading activities. This can improve productivity since one is in a good position to coordinate cargo-handling operations well.

From an environmental perspective, in case of an accidental spill of pollutants such as oil or chemicals, knowledge of ocean currents is crucial. Given the nature of the cargo handled in the port, predicting the spread of a spill using current data can help in quickly implementing containment and mitigation measures to minimize environmental damage.

Acoustic Doppler Current Profilers represent a more efficient and precise means of measuring such currents compared to traditional methods.

3. How do ADCPs using the Doppler principle work?

Measurement Principle

The ADCPs work on the Doppler principle. When an ADCP current meter emits an acoustic signal into the water, it scatters into the moving water particles. Due to the ocean current, the particles of water are in motion; thus, they shift the frequency of the reflected acoustic signal received back by the ADCP profiler. According to the Doppler effect, this frequency shift is related 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 flow meter is able to calculate the current speed and direction of the ocean current at various points within the water column. By sending out signals at multiple angles and at various levels of depth, it is able to produce a profile of the ocean current, displaying how that current changes with depth.

ADCP Deployment in the Port

Shipborne ADCP

The shipborne ADCP could be installed on ships that operate within the Larymna Port area. The ship movements around the port, during which the ADCP profiler is continuously sending acoustic signals to the water beneath, can serve its purpose of monitoring the currents at higher resolutions over wider areas than what is otherwise possible. For instance, in a normal survey of the port by a research or inspection ship with a shipborne ADCP, it can acquire the current patterns across various parts of the port and hence give a comprehensive understanding of the water flow situation.

Fixed ADCP

Fixed ADCPs can be placed at certain fixed positions within the port, like on the seabed near important navigation areas or at the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period. The data collected is useful to analyze the regular current pattern in specific areas of the port. For example, a bottom-moored ADCP installed near the entrance of the port can measure the currents coming in and out to understand the tidal effects and other consistent flow characteristics of that area.

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

Equipment Requirements

In general, measurement of currents in Larymna port requires certain equipment characteristics to achieve high-quality results. Material reliability is one of the important ones. It has to stand the marine environment. Seawater contains salts and other chemicals that may corrode materials with time. It has to endure pressure changes depending on the depth of water and the mechanical forces due to waves and currents.

It would be preferred to be smaller in size, lighter in weight, and have lower power consumption. A compact size makes installation easier at any place in the port, whether on ships, fixed structures such as piers, or even on the seabed. A lighter weight makes the processes of installation and transportation easier. These indicate the reason it should have lower power consumption in equipment operation for continuous operation and longevity without frequent battery changes, which is especially key to long-term monitoring. In addition, cost factors represent how cost is a significant factor of them all. The capability for measuring and reducing operation means deployment may employ a larger number with current measuring tasks while setting multiple measuring points at multiple regions across the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made from titanium alloy. It is well known that titanium alloy has very good corrosion resistance, meaning that this material is able to retain its structural and functional ability for a pretty long time when exposed to seawater. Its high strength-to-weight ratio enables the making of a tough yet relatively lightweight casing. For instance, in the bottom parts of the Larymna port, where higher pressures of water are experienced, the ADCP current meter with a casing of titanium alloy can bear those pressures with ease and continue to measure the currents of water effectively.

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

Selection Based on Usage

Shipborne ADCP: Where the objective, for example, is wide-area surveys of the port waters, during the operation of the ship, then shipborne ADCPs should be applicable. It can cover different sections of the port as the ship moves around, collecting a large amount of data to provide a comprehensive understanding of the overall current situation in the port. It allows one to indicate general flow patterns and variations in different parts of the port waters.

Sitting-bottom ADCP: The sitting-bottom ADCPs are intended for long-term and fixed-point monitoring of places in the port, like near important structures or areas of complex current behaviors. They can continuously record the current data at fixed positions, with valuable insight into the local current characteristics and their possible changes over time.

Buoy-mounted ADCP: In cases where the installation of fixed equipment on the seabed or on ships is not convenient, buoy-mounted ADCPs can be used. They float on the water surface and can measure the currents in the upper layers of the water column. They are relatively easy to deploy and can be relocated if needed, making them suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The choice of frequency for ADCPs is related to the water depth in Larymna port. In areas with a water depth of up to 70 meters, an ADCP with 600 kHz is generally good to go since it will give proper current measurements for this relatively shallow depth. In waters as deep as about 110 meters, it is better to use an ADCP with a frequency of 300 kHz. In very deep parts of the port, with water depth up to 1000 meters, the recommended frequency of the ADCP current profiler should be about 75 kHz for reliable profiling of the ocean currents at such great 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.