ADCP's Application to Ocean Current Measurement in Maputo Port

1. Where is Maputo port?

Maputo Port is situated on the southern coast of Mozambique, along the Maputo Bay. It serves as a crucial gateway for trade not only for Mozambique but also for several land - locked countries in the southern African region.

Port Scale and Throughput

The port has a significant scale, with a variety of berths designed to accommodate different types of vessels. It has the capacity to handle large - scale bulk carriers, container ships, and general cargo vessels. In terms of throughput, Maputo Port processes a substantial volume of goods annually. It is a major exporter of coal, minerals, and agricultural products from Mozambique. Additionally, it imports a wide range of consumer goods, industrial equipment, and construction materials. The annual throughput has been steadily increasing over the years, reflecting the growing economic activities in the region.

Routes and Business

The cargo transport routes within the Maputo Port are widespread. It is directly connected to major ports of Europe, Asia, and the rest of Africa. These routes, therefore, offer the transportation of goods across the globe. Basically, the core business of this port involves cargo handling, that is, container handling, bulk cargo handling, which encompasses coal and iron ore, and liquid bulk handling that includes petroleum products. Others include ship repair, bunkering, and warehousing.

Port Management and Operations

The port is managed by a professional port authority that is responsible for overseeing all aspects of port operations. This includes berth scheduling, traffic management within the port, and ensuring compliance with international safety and environmental regulations. The operations are carried out with the aim of maximizing efficiency and minimizing vessel turnaround times.

Port Facilities

The port is equipped with modern facilities to support its operations. There are large - capacity cranes for container and bulk cargo handling, storage yards for different types of goods, and specialized terminals for liquid bulk. Additionally, there are repair facilities for ships, fuel - filling stations, and modern communication systems to ensure smooth coordination.

Channels and Direct Navigation

The port has well-maintained channels with sufficient depth to allow large vessels to enter and exit safely. The channels are regularly dredged to maintain the required depth. Maputo Port has direct navigation to international shipping lanes, which is essential for its role as a major trading hub in southern Africa.

2. Why should we measure the ocean currents in the Maputo port?

The measurement of ocean currents in Maputo Port is very important due to a number of reasons relating to the management of port operations.

Safety of Vessel Operations

Ocean currents can have a significant impact on the safety of vessels navigating in and around Maputo Port. Currents can affect a ship's course, speed, and stopping distance. For example, strong currents near the entrance of the port or within the berthing areas can render exact vessel handling difficult. With a measurement of ocean currents, pilots and port operators will be better able to predict such effects and thus take proper measures to ensure vessels safely berth, unberth, and transit the waterways with minimal risk of collision and grounding. This reduces the occurrence of accidents-such as collision and grounding-that may harm vessels, their cargo, and port infrastructure.

Cargo Handling Efficiency

Currents can influence the stability of the water surface during cargo handling operations. In Maputo Port, where a large volume of cargo is loaded and unloaded daily, understanding the current conditions is crucial. For instance, if there are strong cross - currents, it may be challenging to position the cargo - handling equipment precisely. By having accurate current data, port operators can plan the optimal time for cargo operations, improving the efficiency of the entire process. This can lead to shorter vessel turnaround times, increasing the port's overall throughput.

Environmental Protection

Knowledge of ocean currents is vital for environmental protection in the port area. In the event of an oil spill or release of other pollutants, the direction and speed of the currents will determine how the pollutants spread. By measuring the ocean currents, port authorities can quickly predict the likely path of the pollutants and take immediate preventive and clean - up measures. This helps to minimize the impact on the marine ecosystem, local fisheries, and the coastal environment.

Among the various methods available for measuring ocean currents, ADCP flow meter has proven to be a highly advanced and convenient option.

3. How do ADCPs using the Doppler principle work?

ADCP Measurement Principle

ADCPs operate based on the Doppler effect. When an ADCP current profiler emits acoustic waves into the water column, these waves bounce off suspended particles (such as sediment, plankton, or water molecules). If these particles are moving (which indicates water movement), the frequency of the reflected acoustic waves will change. This change in frequency, known as the Doppler shift, is directly proportional to the velocity of the moving particles along the direction of the acoustic beam.

Most ADCPs use multiple acoustic beams (usually four or more) arranged in a specific geometric pattern, such as a conical shape. By measuring the Doppler shift in each beam, the ADCP can calculate the velocity components in different directions. Through vector addition of these velocity components, the ADCP can determine the three - dimensional velocity of the water flow at various depths in the water column.

ADCP in Port Ocean Current Measurement Methods

Ship-borne ADCP

Ship-borne ADCPs are installed on the hull of a moving ship. As the ship traverses the waters of Maputo Port, the ADCP continuously measures the ocean currents at different depths. This method is useful for obtaining a broad overview of the current patterns across large areas of the port, including the main shipping channels, outer approaches, and areas where ships may need to maneuver.

Fixed ADCP

Fixed ADCPs are mounted either on the seabed or at other fixed locations in the port. They enable gathering long - term, continuous current information at different points. Therefore, in the case of Maputo Port, such ADCPs may be set near berths, in basins, and also at entrances, to help measure the trend in local variation with time. This data is valuable for understanding the long - term behavior of currents in these critical areas, which can help in port planning and operational improvements.

4. What’s needed for high-quality measurement of Maputo port currents?

Equipment Reliability

For high-quality measurement of currents in Maputo Port, the ADCP flow meter equipment must be highly reliable. The materials used in its construction should be able to withstand the harsh marine environment. The port is exposed to saltwater, which can cause corrosion, and may also experience variable water pressures depending on the depth.

Size, Weight, and Power Consumption

The ADCP meter should be compact in size and lightweight. A smaller and lighter unit is easier to install and deploy, whether it is a ship - borne or a fixed-type ADCP. Low power consumption is also essential, especially for fixed-type ADCPs that may rely on battery power or have limited power sources available. This allows for long-term, continuous operation without frequent battery replacements or power supply disruptions.

Cost-effectiveness

To enable large-scale measurement of ocean currents in Maputo Port, the cost of the ADCP should be reasonable. This would make it possible to deploy multiple units in different locations throughout the port to obtain a comprehensive understanding of the current conditions.

Titanium Alloy for ADCP Casing

Titanium alloy is an excellent choice for the ADCP casing. It offers high corrosion resistance, which is crucial for withstanding the corrosive effects of saltwater in the port environment. Titanium alloy also has a high strength - to - weight ratio, meaning it can maintain its structural integrity while being relatively lightweight. This combination of properties ensures the long - term reliability of the ADCP and simplifies its deployment process.

5. How to Choose the Right Equipment for Current Measurement?

Based on Usage

Ship-borne ADCP

As discussed earlier, ship-borne ADCPs are suitable for broad - scale surveying of the port area. It can cover wide areas in short times and give an overview of current conditions in the different parts of Maputo Port, such as shipping lanes and outer port areas.

Bottom-mounted (Sitting-bottom) ADCP

Bottom-mounted ADCPs are used when long-term, continuous data on current conditions at a specific location is required. In Maputo Port, they can be placed near berths to monitor the currents that affect the berthing and unberthing operations of vessels.

Buoy-type ADCP

Buoy-type ADCPs are useful for measuring surface-layer currents and for obtaining data in areas where fixed installation is not practical. They can be easily deployed and re - positioned, providing flexibility in current measurement.

Based on Frequency

The choice of ADCP profiler frequency depends on the water depth. For water depths up to approximately 70m, an ADCP with a frequency of 600kHz is suitable. This frequency provides high - resolution data for relatively shallow waters. For water depths up to 110m, a 300kHz ADCP is more appropriate. And for water depths reaching 1000m, a 75kHz ADCP is the preferred option.

There are several well-known ADCP brands in the market, including Teledyne RDI, Nortek, and Sontek. However, for a cost-effective and high-quality alternative, the Chinese brand China Sonar PandaADCP is highly recommended. It is constructed with all-titanium alloy materials, ensuring excellent corrosion resistance and durability. Its extraordinary cost-performance ratio makes it an excellent solution for ocean current measurement in Maputo Port. Check out their website at (https://china-sonar.com/) for more.

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