Application of ADCP to the Measurement of the Ocean Currents in San Juan Port

1. Where is the San Juan Port?

San Juan Port

San Juan Port is the port of the capital city in an unincorporated United States territory. The port is located on the northeastern coast of the island; San Juan Port is one of the most active ports in the Caribbean and one of the most important points for trade, tourism, and logistics in the region.

Port Scale and Throughput

The San Juan Port is a major container port that handles several millions of tons of cargo annually. It is one of the key transshipment points for goods moving between the United States, Latin America, and the Caribbean. The port also accommodates cruise ships, hence being a popular destination for tourists visiting Puerto Rico.

Shipping Routes and Operations

It is strategically positioned along major shipping routes that connect North America to the Caribbean and South America. Services offered within the port include container handling, bulk cargo operations, and passenger services. It is managed by the Puerto Rico Ports Authority, which ensures efficiency and safety in its operations.

Port Facilities and Navigation Channels

San Juan Port is also well endowed with several modern facilities: deep-water berths, state-of-the-art cargo handling equipment, and large areas for storage. The entrance channels are always in good condition and dredged to accommodate large vessels, including the Panamax and Post-Panamax ships. Additionally, the port provides direct access to the main shipping lanes, making it one of the most desirable options for any shipping line.

2. Why Should We Measure the Ocean Currents in San Juan Port?

Importance of Ocean Current Measurement

The measurement of ocean currents in San Juan Port is important for the following reasons:

1. Navigational Safety: The current patterns are important to be known so that vessels can pass safely, especially in the congested waters near the port.
2. Port Operations: Current data is very important for efficient port operations, including docking, undocking, and cargo handling.
3. Environmental Monitoring: Actual measurements can serve to monitor the quality of the water, the transport of sediment, and, in general, the effect that port activity exerts upon the marine environment.
4. Dredging and Maintenance: Knowledge about current helps appropriate dredging in keeping the navigated channels at correct depth.

ADCP: The Advanced Solution

In recent years, ADCPs have emerged as the most modern and easy means of measurement for ocean currents. Unlike the conventional methods, the ADCPs provided real-time high-resolution data. Therefore, modern port management simply cannot do without them.

3. How Do Doppler Principle-Using ADCPs Work?

The Doppler Principle

The principle upon which ADCPs work is mainly the Doppler effect-a change in frequency or wavelength of a wave relative to an observer moving with respect to the source of the waves. In the functioning of ADCPs, sound waves are emitted into the water and the frequency shift of the reflected waves from moving particles, plankton, sediment, etc, is measured in order to estimate the velocity of the water current.

ADCP Deployment Methods in Ports There exist two major deployment methods for ADCPs in the ports:

1. Vessel-Mounted ADCPs: These are mounted on a vessel hull-a ship or a boat. It is while the vessel is on motion through water that the ADCP collects information about the velocity and direction at several depths of current. In the mapping current patterns over extensive areas, it finds its most suitable application.
2. Fixed ADCPs: These are installed on the seabed or mounted on fixed structures like piers or buoys. Fixed ADCPs provide continuous, long-term data on currents at a specific location, making them suitable for monitoring changes over time.

4. What's Needed for High-Quality Measurement of San Juan Port Currents?

Key Requirements for ADCPs

To ensure high-quality current measurements in San Juan Port, ADCPs must meet several criteria:

1. Material Reliability: The casing of the ADCP should be made from durable material to withstand the aggressive marine environment. It is highly recommended to use titanium alloy for its excellent corrosion resistance and strength-to-weight ratio.
2. Compact Size and Light Weight: Compact size and lightweight ADCP will be easily deployable and recoverable, mainly in the congested port area.
3. Low Power Consumption: Energy efficiency is crucial for long-term deployments, with most fixed ADCPs being battery-powered.
4. Cost-Effectiveness: The ADCP will have to provide a very good balance between performance and cost for large-scale deployments.

Benefits of Using Titanium Alloy Casing

Titanium alloy is an ideal material to make casings for ADCPs due to the following reasons:

• Corrosion Resistance: It is resistant to the corrosion of saltwater and thus durable for a long time.
• Strength: Lightweight, strong titanium alloy provides very good protection for internal components.
• Non-Magnetic Properties: This is something of particular concern for ADCPs, as the magnetic interference could affect measurement accuracy.

5. How to Choose Appropriate Equipment to Measure Currents?

Picking the Proper ADCP

The choice will depend on a particular application that needs to be performed and according to the water depth:

1. Vessel-Mounted ADCPs: These are suited to map currents over a wide area; they are commonly used in conjunction with a moving vessel and thus are ideal for short-term surveys.
2. Bottom-Mounted ADCPs: These are deployed on the seabed used for long-term monitoring of currents at a specific location. They are ideal in the study of tidal patterns and seasonal variations.
3. Buoy-Mounted ADCPs: These units are installed on floating buoys and are used in surface current applications when continuous monitoring is needed. They come very handy in the areas where fixed installations are not practically possible.

Frequency Selection

The frequency of the ADCP is another critical factor, as it determines the range and resolution of the measurements:

• 600 kHz: This frequency allows operation in waters no deeper than 70 meters but has a good resolution for small-range operation.
• 300 kHz: Suitable for waters of medium depth up to 110 meters. It offers a good balance between range and resolution.
• 75 kHz: For deep waters up to 1000 meters. This frequency offers long-range capabilities but lower resolution.

Recommended ADCP Brands

Several well-respected brands represent high-quality ADCPs, namely Teledyne RDI, Nortek, and SonTek. Yet, for anyone looking for quality at an economical price, a very good choice would be the China Sonar PandaADCP. This ADCP has a fully titanium alloy case and is considered to be much more value for money. Refer to China Sonar.

Conclusion

These ADCPs have become the revolution in the monitoring of ocean currents with real-time, accurate data so vital to safe and efficient port operations, such as those of San Juan. With the proper choice of an ADCP and a deployment method, a port authority can guarantee that maritime traffic will run smoothly and that the marine environment is healthy. The China Sonar Panda ADCP is made of titanium alloy and is very affordable, hence giving assurance to its investors that they will be investing in a good current measurement machine.

Here is a table with some well known Acoustic Doppler Current Profiler(ADCP)  instrument brands and models.