ADCP's Application to Ocean Current Measurement in Abidjan Port

1. Where is Abidjan Port?

Abidjan Port is situated on the Gulf of Guinea in the Côte d'Ivoire, West Africa.

• Port Scale and Throughput: This is one of the most important ports in West Africa. The port has a considerable number of berths and terminals. In the last few years, it has managed to handle huge volumes of cargo, with its annual throughput averaging several million tons. It has the capacity to handle all manner of cargo; from containers, bulk commodities in the form of cocoa, coffee, and other agricultural products to petroleum and their derivatives.
• Routes and Services: The shipping routes that include this port link Europe, the Americas, Asia, and other parts of the world. The full range of cargo handling, which includes loading/unloading, warehousing, clearing customs, logistics, amongst others, has been made fully available. These are also places through which ferry services regularly connect their nearby coastal cities across countries.
• Port Management and Operation: Managed by the Port Authority of Abidjan, it operates with a high level of professionalism and efficiency. The port authority is responsible for maintaining the infrastructure, ensuring safety and security, and facilitating smooth operations.
• Port Facilities: It is also equipped with modern cranes, conveyor systems, and storage facilities. There are container terminals, liquid cargo terminals, and bulk cargo terminals for specialized cargo. Modern navigation aids and communication systems ensure safe operations of ships at the port.
• Waterways and Direct Navigation: The port has deep and wide waterways that can accommodate large vessels. It has adequate direct navigation, making it easy for ships to enter and leave the port. There are no serious natural obstacles in the approach channels, hence smooth passage for ships.

2. Why should we measure ocean currents in Abidjan Port?

Measuring ocean currents in Abidjan Port is of vital importance for several reasons:

• Navigation Safety: The ocean currents in the Gulf of Guinea can be complex. Accurate measurement of these currents helps ship captains to navigate more safely, avoiding areas of strong currents that could cause ships to deviate from their intended courses or increase the risk of collisions.
• Cargo Handling and Ship Berthing: Understanding the currents is essential for efficient cargo handling. It enables optimal scheduling of ship arrivals and departures, as well as ensuring safe and timely berthing and unberthing of ships. Currents can affect the stability of ships during loading and unloading operations, and proper knowledge of them can enhance operational efficiency.
• Port Planning and Expansion: Ocean current data is one of the most essential factors in the future development and expansion of the port. It helps in designing new wharves, breakwaters, and other port infrastructure to withstand the forces of the currents and ensure the long-term stability of the facilities.
• Control Ambiental: Currents are ocean carriers of most of the pollution and marine life. Measuring the currents thus makes it beneficial to monitor the state of the environment in the harbor and its environs for a practical and enduring exploitation of resources there.

Indeed, Acoustic Doppler Current Profiler (ADCP) does much to establish means of obtaining modern data on detailed accurate ocean current measures compared with prior methods.

3. How do ADCPs using the Doppler principle work?

ADCPs operate based on the Doppler principle.

• Measurement Principle: ADCPs emit acoustic signals at a specific frequency into the water column. When these signals encounter moving water particles, the frequency of the reflected signals changes due to the Doppler effect. By precisely measuring this frequency shift, the velocity of the water particles can be determined. ADCPs typically have multiple transducers that emit and receive acoustic signals in different directions, allowing for the measurement of velocity components in three dimensions, thus obtaining a comprehensive picture of the water flow.

Specific Methods in Port Current Measurement

• Shipborne ADCP: Mounted on the hull of a ship, usually on the underside, it measures the current as the ship moves through the water. This method is useful for mapping out large areas of the port and obtaining a broad understanding of the current patterns over a wide range.
• Fixed ADCP: There is one installed on the seabed, or sometimes on fixed port structures like piers or buoys, that measures the currents at a specific location continuously. Such measurements will provide long-term and stable data to understand the local current characteristics and the variation over time.

4. What's needed for high-quality measurement of Abidjan Port currents?

For high-quality measurement of currents in Abidjan Port, the following aspects are crucial:

• Material Reliability: Given the corrosive nature of seawater and the harsh marine environment in the Gulf of Guinea, the equipment must be made of highly reliable materials. This ensures that it can withstand the effects of saltwater, waves, and other environmental factors without suffering from excessive wear or damage.
• Small Size and Light Weight: A compact and lightweight design is beneficial as it allows for easy installation and deployment in various locations. It can be more easily mounted on different platforms, whether it's a small research vessel or a buoy, without causing significant disruptions or stability issues.
• Low Power ConsumptionIn: itself, low power consumption is more of a 'desirable element'. It finds extreme importance particularly with fixed and standalone measurement setups. Low consumption would mean devices operated for lengthy durations without interruptive battery substitution and recharges with minimal need to increase the equipment life cycle leading towards reliable and cheap data harvesting.
• Low Cost: To enable large-scale deployment and widespread use in different parts of the port, the equipment should be cost-effective. This allows more measurement points to be established, providing a more comprehensive understanding of the current patterns.

For ADCPs, using titanium alloy for the casing is advantageous. Titanium alloy is known for its high strength, excellent corrosion resistance, and low density. These properties make it ideal for use in the marine environment of Abidjan Port, protecting the internal components of the ADCP current meter and ensuring its longevity and accurate operation.

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

Determined by Usage

• Shipborne ADCP: Ideal for conducting surveys over large areas of the port and its surrounding waters. It is suitable for when there is a need to quickly obtain a general overview of the current conditions across different regions of the port.
• Bottom-mounted ADCP: Best for long-term, continuous monitoring of currents at specific locations, such as near critical infrastructure or in areas where detailed local current data is required for port operations and safety.
• Buoyant ADCP: Useful for monitoring surface currents and getting a sense of the overall current trends in the port. It can be easily moved and deployed in different areas as needed.

Determined by Frequency

• 600kHz: Suitable for water depths up to about 70m, which is sufficient for many shallow areas within the port, such as near the shore or in some inner harbors.
• 300kHz: Can cover water depths of around 110m, making it suitable for most of the general port areas with moderate water depths.
• 75kHz: Appropriate for deeper waters up to 1000m, which is useful for measuring currents in the outer parts of the port or in areas with greater depths.

There are several well-known ADCP brands in the market, including Teledyne RDI, Nortek, and Sontek. In addition, China Sonar offers the PandaADCP, which is made of all-titanium alloy and provides an excellent combination of quality and affordability. You can find more information on their website at https://china-sonar.com/.

Here is a table with some well known ADCP instrument brands and models.