Application of ADCP to Ocean Current Measurement in Currimao Port

1. Where is Currimao Port?

Currimao Port is located in the municipality of Currimao in the province of Ilocos Norte, Philippines.

Port Scale and Throughput

It is an average-sized port that significantly contributes to the local and regional maritime activities. The structure of the port's throughput consists of a substantial proportion of fishery products since the area is known for its fishing industry. Other than that, there is also general cargo comprising farm produce from the surrounding farms and construction materials for local infrastructure development. The scale of the port continuously changes to accommodate the emerging demand in the growing local economy.

Routes and Business

The Currimao Port is linked to all other domestic ports through various shipping routes, serving as an important transit point in the transport of goods within the Ilocos region and other parts of the country. Major businesses carried out at the port include fishing and trading. The fishing boats often visit this port during the catch of fish unloading and stocking their requirements again. This place also gives opportunities for selling local hand-made products and items, showcasing entrepreneurship and culture exchange among these people.

Port Management and Operation

The port is managed by local port authorities who are responsible for ensuring efficient and safe operations. They oversee vessel traffic control to prevent congestion and accidents. Berthing arrangements are carefully managed to optimize the use of available space. Cargo handling procedures are in place to ensure the timely and proper transfer of goods. The port authorities also work on security measures and collaborate with other maritime agencies to safeguard the port and its users.

Port Facilities

The port has berthing facilities that can handle vessels of different sizes, from small fishing boats to medium-sized cargo vessels. There are storage facilities for fishery products and other cargoes. It has facilities for the maintenance and repair of vessels, including workshops and supply stores. Other basic facilities like comfort rooms and waiting sheds have also been provided for the convenience of the port users.

Channel and Direct Navigation

Currimao Port has a well-defined channel that is safe to navigate. The channel is dredged to ensure depth for vessels, considering the tidal changes. There are buoys and markers that were placed to guide the ships entering or leaving the port. Such aids enable mariners in direct navigation and help to avoid shallow areas and submerged rocks.

2. Why is it necessary to measure the ocean currents in the Currimao port?

Optimizing Port Operations

It is vital to know the current situation in Currimao Port to enable proper vessel management. Understanding the direction and speed of flow helps in undertaking precise berthing and mooring of vessels. By accurate positioning at the time of docking by understanding the nature of currents, collision can be avoided and the safety of the ships as well as port infrastructures can be ensured. This again is quite necessary because vessels operating at the port include those carrying cargo as well as engaged in fishing activities.

Benefiting the Fishing Industry

For the local fishing industry, ocean current measurements are indispensable. Currents carry nutrients and affect the distribution of fish and other marine organisms. Accurate current data enables fishermen to locate areas of higher fish concentration to increase their catch and productivity. It also helps in predicting the movement patterns of fish, enabling more strategic fishing operations.

Infrastructure and Environmental Considerations

These current measurements are of paramount importance in the infrastructural sector for the design and maintenance of port structures, as such currents may exert considerable hydrodynamic forces on the stability and durability of quay walls, piers, and other facilities. Currents also play an important role in environmental management, as dispersion of pollutants or any substance in water has an essential role in protecting the local marine ecosystem.

In this paper, Acoustic Doppler Current Profiler (ADCP) is more modern and handy compared with conventional methods of measurement. It also can provide real-time current profiles in detail that would be helpful to monitor ocean currents within a given port area with higher accuracy and efficiency.

3. How do ADCPs using the Doppler principle work?

They work on the principle of the Doppler. An ADCP current meter emits acoustic signals into the water. The acoustic waves interact with moving particles in the water, such as suspended sediments or small organisms. When the acoustic waves hit these moving particles, due to the Doppler effect, there is a shift in frequency of the reflected waves.

This frequency shift of the reflected signals is measured by the ADCP meter. With the use of specific algorithms and calibration, it can deduce the velocity of the moving particles. As the movement of these particles is due, for the most part, to the ocean current, it is possible for the ADCP profiler to calculate the velocity of the current.

ADCP in Port Ocean Current Measurement

Shipborne ADCP

Shipborne ADCPs are installed on vessels operating in the port area. During this movement of the ship through water, ADCP current profiler continuously emits an acoustic pulse, normally at a direction of travel downward and to the sides of the ship. In general, current velocities at every different depth along the ship's travel path are measured with the help of an ADCP. Data gathered by this while traveling can be combined into a complete map showing the current field in the entire port area. This gives a good insight into the prevailing patterns during a ship's voyage.

Fixed ADCP

Fixed ADCPs are installed in fixed locations within the port on the seabed or on fixed structures like piers or breakwaters. The ADCPs at that particular location continuously monitor the ocean currents over time. Fixed ADCPs will provide information on the long-term and steady current conditions at critical points within the port area. It would serve as a reference to operations, research, and structural planning within the port.

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

Equipment Requirements

For the measurement of the ocean currents in Currimao Port, it has to be equipped with reliable materials that could provide high-quality measurements. It must withstand the harsh marine environment due to corrosive seawater, different pressures due to water depth, and even impact forces from floating debris.

Other important considerations include size and weight. The equipment will definitely be at an advantage if it is smaller in size and lighter in weight, especially on vessels or when there is not enough space on fixed structures. This will give some leeway in placing the equipment.

Another important factor is the power consumption. The low-power-consuming device is preferred because it can operate for longer hours without the need to change batteries frequently or supply excessive energy. This is so critical for fixed ADCPs that may not have easy access to a continuous power source.

Advantage of Titanium Alloy Casing

The casing of ADCPs made of titanium alloy is one of the best options. The corrosion resistance of the titanium alloy is excellent, which means that it may withstand the corrosive effect of seawater for a longer period. It will also help to maintain the integrity and performance of the ADCP flow meter. Besides, it has a high strength-to-weight ratio; thus, enabling durable yet lightweight designs, which is good in installation and operation. Besides, titanium alloy withstands high pressures at greater depths, which is appropriate for use in different water depth conditions in the port area.

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

Based on Usage

Shipborne ADCP: This would be the better choice when the main goal is to obtain a general overview of current patterns in the port during vessel movement. It can cover areas in the port as the ship moves around, hence giving an overview of the current situation in that area.

Bottom-mounted (Sitting on the seabed) ADCP: Bottom-mounted ADCPs are more appropriate for long-term and continuous monitoring of the current condition at specific fixed locations, such as near important port structures or in areas where the characteristics of the current are of special interest for research or operational reference. They can provide stable and consistent data over an extended period.

Buoy-mounted ADCP: In cases where the area is inaccessible for fixed installations or even ship operations, measurements of currents can be recorded by buoy-mounted ADCPs. These can drift with currents to a certain extent and still record data on the current fluctuations in those areas.

Based on Frequency

A 600 kHz-rated ADCP is very often quite adequate for water as shallow as 70 meters. This can give a very high degree of resolution in the relatively shallow areas of the port.

For as deep as 110 meters of water, it is often better to opt for an ADCP with a frequency of 300 kHz, which has a better range of water column penetration, whereby at that depth, accurate current measurements can be attained.

To scan further areas and water depth up to 1000 meters, it is recommended to use an ADCP with a 75 kHz frequency. It can support such big depth ranges and measure ocean currents with acceptable accuracy.

There are several well-known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, it's worth mentioning a cost-effective Chinese ADCP brand-China Sonar PandaADCP. It is made of all-titanium alloy material and offers an impressive price-performance ratio. You can visit its website at (https://china-sonar.com/) for more information.

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