ADCP in Megara Port: Ocean Current Measurement

1. Location and General Information about Megara Port

Geographical Location

Megara Port is situated in the city of Megara, Greece. It is a port of medium size and traffic flow. The position of the port is such that it has easy access to the Saronic Gulf and further into the Aegean Sea and the Mediterranean.

Local and Regional Trade Role

The port is very important in the local economy and caters for a wide range of transportation. It deals with agricultural products from the surrounding areas, such as grains, fruits, and vegetables. It also handles construction materials, light industrial products, and some imported goods that are distributed to the local market and other nearby regions.

Port Facilities

Berths

The port has several berths designed to receive different sizes of vessels. The port will have berths for receiving small to medium-sized cargo ships and fishing vessels that are equipped with standard mooring and docking facilities; bollards and fenders protect both the ships and the berths in performing the docking and undocking process.

The depth of the berths is kept such that ships having a reasonable draft can comfortably come in safely. To ensure the berths will be able to handle traffic expected, regular dredging operations are carried out.

Cargo-handling Equipment

Along the quay, a wide range of cargo - handling equipment is available. Agricultural products are transferred from the ships to the storage areas by means of conveyor belts and forklifts. For construction and other bulk cargoes, cranes and grabs are available for loading and unloading.

There are also mobile cranes and other lifting equipment to handle containers and general cargo, which allows for efficient transfer between the ships and the storage facilities of the port.

Storage Facilities

Megara Port has different types of storage areas depending on the nature of the cargo. For perishable agricultural products, there are well-ventilated warehouses and cold-storage facilities to maintain product quality.

It is with open-air stockpiles and covered storage sheds for construction materials and other non-perishable goods, the storage and management of containerized cargo in a container yard.

Channel and Navigation Aids

The channel of the port is dredged to proper depth and width for safe passage of ships. Navigation aids include buoys, beacons, and a radar system. Real-time information regarding the position and movement of ships around the port helps the system to avoid collisions and lead vessels safely into and out of the port.

3. Importance of Measuring Ocean Currents in Megara Port

Safety of Vessel Navigation

The knowledge of ocean currents is of prime importance for the safety navigation of vessels. When the captains are approaching the berths or navigating the channel of the port, they have to know the speed and direction of the currents. A cross - current near a berth can make the process of docking difficult and hazardous.

For instance, if a ship is coming to a berth against a strong current, he might have to adjust the speed and angle of approach to ensure smooth and safe docking. With correct current measurements, captains are able to make better-informed decisions and reduce the risk of accidents such as collisions with the berth or other vessels.

Optimization of Port Operations

Current data is essential for optimizing the port's operations. By understanding the tidal currents and other regular flow patterns, port authorities can more efficiently schedule the arrival and departure of ships.

This enables better allocation of berthing resources and more effective planning of loading and unloading activities. As a result, productivity can be improved through better coordination of cargo-handling operations.

Environmental Considerations

In the event of an accidental spill of pollutants such as oil or chemicals, knowledge of ocean currents is invaluable. Given the types of cargo handled in the port, being able to predict the spread of a spill using current data allows for the quick implementation of containment and mitigation measures to minimize environmental damage.

4. Working Principle of ADCPs (Acoustic Doppler Current Profilers)

Doppler Principle

ADCPs are based on the Doppler principle. An Acoustic Doppler Current Profiler (ADCP) sends an acoustic signal into the water, which scatters off the moving water particles. Due to the movement of the water particles caused by the ocean current, a frequency shift in the reflected acoustic signal received back by the ADCP current meter occurs. According to the Doppler effect, this frequency shift is related to the velocity of the water flow. The greater the speed of the water particles, the larger the frequency shift of the reflected signal.

Current Speed and Direction Calculation

By processing the amplitude and direction of the frequency shift, the speed and direction of the ocean current at various points in the water column can be determined by the ADCP meter.

The ADCP flow meter sends out signals at multiple angles and different depths. In that way, it can profile the ocean current, indicating how the current changes with depth. This depth - profiling capability is essential in understanding the complex current patterns in a port environment.

5. Deployment of ADCPs in Megara Port

Shipborne ADCP

A shipborne ADCP may be installed on ships operating within the Megara Port area. In such a case, an ADCP current profiler that travels in tacks around the port continually sends acoustic signals into the water below. The travel of the ship enables the ADCP meter to survey a wide area and collect current data at several locations.

For instance, a research or inspection ship with a shipborne ADCP could do a routine survey of the port and collect data on the current patterns over different areas of the port, thus giving an overview of the water flow situation.

Fixed ADCP

The fixed ADCPs can be placed at some specific, fixed locations in the port, like at the bottom of the ocean floor in areas of key interest around navigation or at the entrance and exit of the port. These ADCPs continuously record the ocean currents at fixed positions over a long period. The current information gained through the fixed ADCPs is a good way to analyze regular currents in specific areas of the port. For example, a fixed ADCP installed near the entrance of the port records the incoming and outgoing currents, helping to understand tidal effects and other consistent flow characteristics in that region.

6. Requirements for High-Quality Measurement of Megara Port Currents

Equipment Characteristics

Material Reliability: The hardware must be able to function in a harsh marine environment; salinity and other chemicales in seawater cause material degradation over some period of time. Besides, a change of pressure with depth is an important factor to consider along with the mechanical effects due to waves and currents.

Size, Weight, and Power Consumption: Small in size, lower weight, and low power consumption. Compact size allows for easier installation in various locations within the port, on ships, on fixed structures such as piers, or on the seabed. A smaller weight makes installation and transportation easier.

Low Power Consumption: Low power consumption ensures that the equipment is able to run continuously over long periods without frequent changes of batteries or excessive power supply, especially in long-term monitoring applications.

Cost: Cost is also a factor. A lower-cost enables the port to deploy more measuring devices for more extensive current monitoring across different areas of the port.

Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance, with the ability to maintain its structure and functionality even when subjected to seawater for an extended period of time.

High strength-to-weight ratio; the casing can be sturdy but at the same time lighter in weight. For instance, the Megara port is partly deeper, where higher pressures of water are experienced; the ADCP profiler with the casing made of a titanium alloy can bear such pressure and give current measurements correctly.

7. Selecting the Proper Current Measurement Equipment

Selection According to the Usage

Shipborne ADCP: Where the intention is to carry out wide-area surveys of the port waters while the ship is in operation, shipborne ADCP will be suitable. This can, over time and as the ship moves, cover sections of the port to gather many data points to give an overview of the overall current situation in the port. This is useful in mapping the general flow patterns and variations across different areas of the port waters.

Sitting-bottom ADCP: Sitting-bottom ADCPs should be used for the monitoring of specific locations in a port for longer periods, which requires fixation, such as in proximity to important infrastructure or where the flow behaviors are complicated. They can record the continuous current data at fixed positions in places, which helps obtain insight into the characteristics and possible variations in local currents over some time.

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. Relatively easy to deploy, and relocation is possible when needed; thus, suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The choice of frequency for ADCPs depends on the water depth in Megara port. For areas with a water depth of up to 70 meters, an ADCP current meter with a frequency of 600 kHz is usually a good choice as it can provide accurate current measurements in this relatively shallow depth range.

For deeper waters, up to about 110 meters, the more advisable is an ADCP with a frequency of 300 kHz. In very deep parts of the port with water depth up to 1000 meters, it is recommended to use an ADCP meter with a frequency of 75 kHz to reliably profile ocean currents at that great depth.

There are several well - known ADCP profiler 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.