Application of ADCP to Measurement of Ocean Currents at Mombasa Port

1. Where is Mombasa Port

Mombasa Port is situated on Kenya's eastern coast along the Indian Ocean. It is the largest and busiest port in East Africa.

Port Scale and Throughput

The port has a colossal scale, comprising several berths, which can accommodate several vessels, such as large-scale container ships, bulk carriers, and oil tankers. It handles a reasonable percentage of cargo annually. This port also serves as one of the important entry and exit points for imported and exported goods not only for Kenyans but also for other inland countries in the region, such as Uganda, Rwanda, and South Sudan. It has increased its annual cargo throughput for several years continuously, where major components were the container traffic, general cargo, and bulk commodities like petroleum products, cement, and grains.

Routes and Business

Mombasa Port has grown a vast web of shipping routes connecting it to other major global ports. Shipping services range in its areas: Europe, Asia, and the Americas. The scope of business encompasses a wide range of activities:. This port works as a transshipment hub where the goods are transferred from big vessels to small ones for being dispatched at regional ports. The import-export operation is also another business unit that industries use the port to import raw materials and export their finished products. Other activities of the fishing-related sectors take place within the area of the port where the fishes are also exported to many international destinations.

Port Management and Operations

The port is under the management of the Kenya Ports Authority (KPA). The KPA oversees the smooth running of the port by managing berths, vessel traffic, and cargo handling. Modern terminal facilities with up-to-date cargo handling equipment, including cranes, forklifts, and conveyor belts, exist at the port. Regular maintenance is performed to ensure seamless operation. The port also has a well-trained workforce to handle different aspects of port operations, from cargo handling to administrative tasks.

Port Facilities

Mombasa Port is equipped with a variety of facilities. There are multiple container terminals, each with its own set of cranes capable of handling large-capacity containers. The liquid bulk terminals are designed to handle the storage and transfer of petroleum products safely. Besides that, there are dry bulk terminals that deal with coal and cement commodities. Added to this, the port has facilities for ship repair and maintenance, which include dry docks where ships are repaired and serviced.

Channels and Direct Navigation

The port has a well-maintained navigational channel that allows vessels to enter and exit safely. The depth of the channel is regularly dredged to accommodate larger vessels. There are direct shipping routes to major ports in Asia, such as Dubai, Singapore, and Shanghai. These direct routes enhance the port's competitiveness and efficiency in international trade.

2. Why should we measure the ocean currents in the Mombasa Port?

Ocean current measurement in Mombasa Port is a very important input for the management of port operations. Accurate current data would help in navigation; the currents around the port may influence the speed and direction of vessels. Thus, knowing the current conditions can help ship captains plan their route more effectively to avoid collisions and groundings. This is particularly important during berthing and un - berthing operations, where the movement of the vessel has to be precisely controlled.

Secondly, current measurements are important in cargo handling operations. Strong currents can make it difficult to position cargo-handling equipment accurately. Understanding the current patterns enables port operators to schedule cargo handling activities at optimal times, improving the efficiency of the entire process.

Thirdly, ocean current data is essential in terms of environmental protection. Currents in the port area may determine the dispersing path of pollutants. In this way, the port authorities can better predict the spread of oil spills or other contaminants by monitoring the currents to undertake timely and effective response measures.

Finally, long-term current measurements can provide valuable information for port expansion and infrastructure planning. By analyzing historical current data, planners can determine the best locations for new berths, terminals, or breakwaters.

Acoustic Doppler Current Profiler (ADCP) is the more advanced and convenient method of measuring ocean currents in Mombasa Port compared to the traditional methods. It can provide high-resolution, real-time data, which is essential for the complex operations in the port.

3. How do ADCPs using the Doppler principle work?

ADCP's Measurement Principle

ADCPs operate based on the Doppler principle. An ADCP current meter emits acoustic signals into the water column. When these signals encounter moving particles (such as suspended sediment or plankton) in the water, the frequency of the reflected signals changes. This change in frequency, known as the Doppler shift, is proportional to the velocity of the particles along the acoustic beam.

By measuring the Doppler shift of the reflected signals from multiple acoustic beams-usually four or more in a typical ADCP-the ADCP can calculate the three-dimensional velocity of the water flow at different depths. The ADCP divides the water column into several layers or bins and, for each bin, calculates its velocity components.

ADCP in Port Current Measurement: Specific Methods

Ship-borne ADCP

An ADCP current profiler mounted on the hull of a moving vessel. The ship follows a path around the port area, and as it does so, the ADCP measures the currents in the water along that path at many depths. This can be useful in obtaining a broad area snapshot of the current conditions in the port. The ADCP mounted on the ship can survey large areas rather quickly and provides an overview of the variation of the currents over all parts of the port.

Fixed ADCP

A fixed ADCP is deployed at a specific location in the port, such as near a berth or in a channel. It continuously monitors the current conditions at that particular site. Fixed ADCPs are ideal for obtaining long - term, high - frequency data on the local current patterns. They can provide understanding of variations on a day to day and season-to-season scale and a very long period and help for operations at port level and environment surveillance.

4. What are the conditions required to attain good measurements for the Mombasa Port currents?

Dependability in Equipments

The ADCP flow meter equipment should be highly reliable for high-quality measurement of currents in Mombasa Port. With the harsh marine environment-characterized by factors such as saltwater corrosion, strong waves, and temperature changes-the ADCP needs to be made from durable materials.

Size, Weight, and Power Consumption

The ADCP meter should be compact in size and lightweight. A smaller size allows for easier installation, whether on a ship or at a fixed location. A lightweight design also reduces the impact on the stability of the installation platform. Additionally, low power consumption is essential, especially for fixed-deployed ADCPs that may rely on battery power or small - scale power generation systems.

Cost-effectiveness

To enable large-scale measurement in the port area, the ADCP should be cost-effective. High-cost equipment may limit the number of units that can be deployed, reducing the comprehensiveness of the data collection.

Titanium Alloy Casing

The casing of the ADCP is preferably made of titanium alloy. Titanium alloy has several advantages. It is very resistant to corrosion by saltwater and, therefore, suitable for longtime use in Mombasa Port. It is also rather lightweight compared with other materials with good resistance to corrosion, for example, stainless steel. Titanium alloy is also strong enough despite its lightweight and can bear mechanical stresses in a marine environment and ensure the long life of the ADCP.

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

Based on Usage

Ship-borne ADCP

If the goal is to map the current conditions across a large area of the port quickly, a ship - borne ADCP is the preferred choice. It can be easily installed on a survey vessel and provide data while the ship is in motion.

Bottom-mounted (Sitting-bottom) ADCP

For long - term monitoring of current conditions at a specific location, such as near a critical berth or in a narrow channel, a bottom-mounted ADCP is more suitable. It can be deployed on the seabed and continuously collect data over an extended period.

Buoy-mounted ADCP

A buoy-mounted ADCP is useful when the measurement needs to be carried out at a floating location. It can provide data on the surface and near-surface current conditions, which is valuable for understanding the interaction between the atmosphere and the ocean in the port area.

Based on Depth

The choice of ADCP profiler frequency is related to the measurement depth. An ADCP with a frequency of 600kHz is suitable for water depths of less than 70m. This frequency provides high - resolution data in relatively shallow waters, which is often the case in parts of Mombasa Port. For water depths up to 110m, a 300kHz ADCP is more appropriate. It can penetrate deeper into the water column while still maintaining a reasonable level of resolution. For very deep waters, like in some outer - port areas or channels up to 1000m depth, the best choice is a 75kHz ADCP.

There are several well-known ADCP brands in the market, like Teledyne RDI, Nortek, and Sontek. However, for those looking for cost-effective yet high-quality options, the Chinese brand China Sonar PandaADCP is highly recommended. It is made of all-titanium alloy material, ensuring excellent corrosion resistance and durability. With its incredible cost-performance ratio, it offers a great solution for current measurement in Mombasa Port. You can visit their website at (https://china-sonar.com/) for more information.

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