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

1. Where is Patras Port

Location and Significance

Patras Port is one of the most important harbors in Greece, placed within the city of Patras. It is a strategic transport node, mainly because of its favorable position on the western coastline of Greece. The port acts as a link between Greece and Italy, with various ferry services crossing the waters. It also has connections with other Mediterranean ports and plays a very important role in both passenger and cargo transportation.

Role in Regional and International Trade

The port acts in a wide range of trade activities. It holds a diversified cargo mix like containers, vehicles, agricultural produces, fruits, and vegetables, and industrial goods. The imported and exported goods via the Patras Port significantly influence the local and regional economy of the country. It serves as an important entry to tourism, with many tourist cruise ships and ferries arriving at this port.

2. Port Facilities

Berths

The port has a comprehensive set of berths designed to accommodate various vessel types. There are deep - water berths suitable for large container ships, cruise liners, and Ro - Ro (Roll - on/Roll - off) vessels. These berths are equipped with advanced mooring and docking systems. High - quality fenders and bollards are used to ensure the safe arrival and departure of ships, even in challenging weather conditions and strong currents.

The port authority regularly maintains the berths to ensure the right depth of water and structural intactness. Dredging is done whenever necessary to keep berths accessible to vessels drawing different drafts.

Cargo-handling Equipment

On the quay, there is a gamut of cargo-handling equipment. For containerized cargo, modern gantry cranes efficiently load and unload containers on and off the vessels. Then there are special ramps, with loading equipment, for wheels. In the case of bulk and general cargo, conveyor systems, forklifts, and cranes make the movement of goods between vessels and storage areas possible. The port is also equipped to handle perishable goods with the help of refrigerated containers and temperature-controlled storage areas.

Storage Facilities

There is also plenty of storage for varied types of cargo. The container yard is in order, with a system for efficiency in both the storage and retrieval processes of the containers. For the agricultural products, there are well-ventilated warehouses and temperature-controlled areas where goods are kept without loss in quality. There is also high-capacity storage in large sheds for industrial commodities and automobiles.

Security to safeguard the cargo stored at the port is provided by access controls and surveillance systems.

Navigation Aids and Channel

The channel of the port has a depth and width such that the ships can comfortably and safely pass through. This is done through the frequent dredging to deepen and expand it for the jumbo vessels. It uses a system of buoys and beacons besides having an advanced radar. The radar system provides real-time information on the position and movement of other vessels in the area, thus helping to prevent collisions and ensuring smooth traffic flow in and out of the port.

3. Importance of Measuring Ocean Currents in Patras Port

Vessel Navigation Safety

It is very important to measure ocean currents for vessel safety in Patras Port. Current speed and direction are of paramount importance for the captains when approaching berths or passing through the channel. A strong cross-current near a berth can make the docking process very difficult and dangerous.

For instance, when a vessel is coming up to the berth with a strong current, it will need to vary its speed and angle of approach. Precise current measurement enables the captain to make fully-informed decisions that will minimize collision and other accident risks like grounding and hitting the pier.

Optimization of Port Operations

The current data is highly useful in the betterment of the operation at Patras Port. Understanding the tidal currents and other regular flow patterns, port authorities are able to schedule the arrival and departure of ships more efficiently. This allows for a more efficient use of berthing resources and more effective planning of loading and unloading activities.

For instance, ships can be timed to arrive during favorable current conditions, reducing the time and energy required for docking and undocking. This leads to increased productivity through better coordination of cargo - handling operations and can also result in cost savings for shipping companies.

Environmental Considerations

Knowledge of ocean currents is of great value should there be an accidental spilling of pollutants like oil and chemicals. Due to the cargo held within the port, including that which could be dangerous in nature, using current data one can predict the flow a spill will take to thus quickly institute containment and mitigation steps to reduce the environmental impacts caused.

The potential of realistically modeling pollutant distribution using current conditions enables rapid mobilization of efforts to deploy recovery operations that could minimize harm to the marine environment and coastline.

4. Operating Principle of ADCPs

Principle of Doppler

ADCPs are basically based on the principle of the Doppler effect. So when it emits an acoustic signal into the water, from an Acoustic Doppler Current Profiler (ADCP), say, it interacts with moving particles of water. These are in motion under the flow of the current; as a result, frequency shifts associated with the reflected acoustic signal reach the ADCP current profiler with a variation.

Accordingly, according to the Doppler effect, there is a shift in the frequency, which is a function of the water flow's velocity: the magnitude of the shift being proportional to the speed at which the water particles move, or, faster the speed of water, greater would be the shift in the reflected signal's frequency.

Calculating Current Speed and Direction

The ADCP calculates the speed and direction of the ocean current at discrete depths in the water column by analyzing the magnitude and direction of this frequency shift. The ADCP flow meter sends out signals at multiple angles and different depths to create a profile of the ocean current.

The depth-varying current profile presents a comprehensive view of the current structure. For instance, it might be stronger near the surface and weaker at deeper layers, or there might be complex vertical current patterns driven by processes such as tidal mixing or the presence of topography underwater.

5. ADCPs Deployment in Patras Port

Shipborne ADCP

A shipborne ADCP can be installed on ships operating in the Patras Port area. While the ship moves around the port, the ADCP profiler continuously sends acoustic signals into the water underneath. The movement of the ship enables the ADCP to cover a wide area and collect current data from different locations.

For instance, a shipborne ADCP on a research or inspection ship doing a routine survey of the port would be able to acquire current patterns for most of the parts of the port and thus be truly representative of the prevailing situation as far as water flow within the port is concerned. This data may then be given to update nautical charts for real-time information to other vessels.

Fixed ADCP

Fixed ADCPs can be installed in specific, fixed locations in the port, for example, on the seabed in areas where navigation is very important, or at the entrance and exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period.

The data from fixed ADCPs is applicable in the analysis of the regular current patterns in certain areas of the port. For example, a fixed ADCP placed near the entrance of the port would record the incoming and outgoing currents, thus enabling the analysis of the tidal effects and other consistent flow characteristics of that area. This will be useful in predicting when it is best for ships to enter or leave the port according to the current conditions.

6. High - Quality Measurement Requirements for Patras Port Currents

Equipment Characteristics

Reliability of Material: Equipment should be resistant to seawater conditions. Seawater contains salts and various chemical substances that can corrode materials with time. Additionally, equipment should support changes in pressure at various levels of depth and resist the mechanical forces of waves and currents.

Size, Weight, and Power Consumption: The smaller, the lighter, and with lower power consumption. With a smaller size, installation at several locations in the port is conveniently done, whether on the ship, fixed structure, or on the seabed. Smaller weight simplifies both the installation and transportation process. The low power consumption allows the devices to run for days and weeks without frequent battery replacements or high power supplies, which becomes very important in applications related to long-term monitoring.

Cost: Cost is another important factor. Lower cost allows the port to deploy more measuring devices in order to provide full current monitoring in different areas of the port.

Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. The main reason is that titanium alloy has excellent corrosion resistance; it will keep its structural integrity and functionality even when exposed to seawater for a long time.

Its high strength - to - weight ratio allows for the construction of a durable yet relatively lightweight casing. In the deeper parts of the Patras port where higher water pressures are present, an ADCP with a titanium alloy casing can effectively withstand these pressures and continue to provide accurate current measurements.

7. Choosing the Right Equipment for Current Measurement

Selection Based on Usage

Shipborne ADCP: Where wide-area surveys of the port waters are intended, and the ship is to be operated, the shipborne ADCP will be appropriate. The instrument can then cover areas of the port as the ship moves around, giving substantial amounts of data that lead to a general understanding of the overall current situation at the port. This will be useful in mapping general flow patterns and variations between different areas of the port waters.

Sitting-bottom ADCP: For long-term and fixed-point monitoring of certain positions in the port, such as near important infrastructure or areas with complex current behaviors, bottom-sitting ADCPs are more appropriate. They can record continuously the current data at those fixed positions, which is very valuable for the study of the local current characteristics and their variations.

Buoy - mounted ADCP: When it is not convenient to install fixed equipment on the seabed or on ships, 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 frequency for ADCPs would depend on the water depth in Patras port. For areas with a water depth of up to 70 meters, an ADCP with a frequency of 600 kHz is usually a good choice as it can provide accurate current measurements in this relatively shallow depth range.

When working in deeper waters, up to about 110 meters, a 300 kHz frequency ADCP would be more advisable. In cases of very deep areas of the port, the water depth may reach 1000 meters; in such a scenario, it is recommended to use an ADCP with a frequency of 75 kHz to obtain 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.