ADCP's Application to Ocean Current Measurement in Colombo Port

1. Where is Colombo port?

It is located in Colombo, the capital city of Sri Lanka, and is considered one of the most important ports in South Asia and holds a considerable place in the global maritime transport network.

Colombo Port is a large-scale port with extensive lengths of quay and a considerable number of berths. It handles a vast volume of cargo annually, which includes containers, bulk cargo, and different types of general cargo. Over the years, its throughput has increased gradually to handle the ever-growing trade exchange between Asia and Europe, among other parts of the world.

It acts as a hub for various shipping lines across different parts of the world. Several shipping lines connect it with main European, Asian, and Middle Eastern ports on regular routes, while its businesses have covered almost everything, starting from handling the major exports of Sri Lanka like tea, spices, textiles, etc., to importing different types of manufactured goods, machinery, and raw materials.

The port management is handled by professional teams, and the operational systems ensure the facility is running smoothly for cargo handling and vessel berthing along with other port-related services. Stringent safety and security to protect the port's operations and the ships calling at it are present.

The modern container terminals are equipped with advanced handling equipment: quay cranes, gantry cranes, and automated stacking systems. Besides that, there is space for storing different types of cargo in appropriate conditions, as well as the necessary warehouse spaces. The port is also equipped with fueling stations, repair yards, and other supportive facilities for ships.

The port has well-maintained channels with appropriate depths to allow large vessels to enter and leave safely. It promotes direct shipping connections with more than a lot of ports around the world, reducing transit times and enhancing trade efficiency.

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

Accurate measurement of ocean currents in Colombo port is of great significance for its port operation and management. It allows for the optimization of vessel navigation. With current patterns and velocities, the port authorities are in a position to advise the ships on how to enter or leave the port with more precision. This would also contribute to vessels' fuel economy and the shortening of their voyages by taking advantage of current conditions by changing speed and/or course in real time for greater efficiency at sea.

Knowledge of ocean currents is crucial for the safety of port operations. Strong or unpredictable currents may lead to hazardous situations for ships during berthing and unberthing processes. With proper current data, appropriate safety measures can be taken to avoid accidents such as collisions with quay walls or other vessels.

Moreover, it helps in planning and maintenance of port facilities. Ocean currents can affect sedimentation patterns around the port area; thus, monitoring of the same will help port managers to plan dredging activities accordingly to avoid interference with the integrity of port infrastructure.

During the last few years, ADCP flow meter has represented a more modern and handier method of measurement of ocean currents compared to the more traditional ways. It can give real-time and quite accurate data over a wide range of depths that really allows port operators to make timely and informed decisions.

3. How do ADCPs using the principle of the Doppler work?

The ADCPs work on the principle of the Doppler effect. They send acoustic signals into the water column. Where these acoustic waves run into moving particles in the water, like suspended sediment or small organisms, because of the Doppler effect, the frequency of the reflected waves is changed. Through analysis of the difference between the emitted and received frequencies, the velocity of the moving particles and thus the velocity of the ocean current can be calculated.

Shipborne ADCP

These are usually applied in Colombo port. A ship with an ADCP current profiler on board cruises on predefined tracks in the area of interest at the port. While the ship is in motion, the ADCP current meter continuously sends acoustic signals to the water beneath and to the sides, while it measures current velocities along the track of the ship at various depths. Data acquired onboard can be processed or transmitted back to shore for further analysis.

Fixed ADCP

Fixed ADCPs are installed on specific sites in the port, such as on the seabed or fixed structures like piers. In turn, the ADCPs will be continuously monitoring the ocean currents in a fixed position. The long-term and stable data of the current condition in that particular area of the port will be repeatedly monitored. The information is worth acquiring to get the regular patterns and variations of currents over time.

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

For high-quality measurement of the currents in Colombo port, several factors concerning the equipment are very important. First, it is on the reliability of the materials the equipment are made from. For instance, the casing of an ADCP profiler is best made from a titanium alloy. The usage of a titanium alloy has several outstanding advantages: it has a high resistance to corrosion, especially in sea water faced by the equipment at all times. Due to the marine environment having such harsh chemical and physical conditions, it should allow the ADCP meter to withstand them for very long periods for its durability and stability.

The size of the equipment should be small and the weight light. This will make installation easier whether on ships or at fixed locations in the port. A lighter and smaller ADCP reduces the impact it will have on the vessels or structures it is attached to.

Besides, low power consumption is needed. In a port environment where continuous operation is often required, low power consumption means the equipment can operate for a long period without needing frequent battery replacements or excessive energy supply. In addition, it should be low cost to enable large-scale measurement. With a reasonable cost, more ADCPs can be deployed in different areas of the port to obtain a comprehensive understanding of the ocean current situation.

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

Selection of proper equipment for the measurement of current in Colombo port is determined by the type of usage.

By Installation Type

• Shipborne ADCP: Can be installed where the measurement is to be taken on the move with the ship's movement and for particular survey areas in the port area. This has a considerable area it can cover, with the movement of the ship.
• Bottom-mounted ADCP: This is applicable to the fixed-point long-time monitoring at some key positions in the port, such as near the entrance channels or around important berths, and can provide continuous data stably about the local current condition. 
• Buoy-mounted ADCP: It is applicable to the areas where floating monitoring is proper-for example, open water within the port, to get an idea about the surface and upper layer current pattern.

The basic models differ by frequency; in return, there are several suitable frequency options with regard to various water depth options. A good example of frequency involves the fact that a 600 kHz ADCP is intended to represent an effective choice in which water depth applies not more than 70 meters ; likewise, 300 kHz could perform in the wide range up to 110 meters, satisfying areas in most port channels. While the 75 kHz ADCP is for much deeper waters-up to 1000 meters-useful for those places where deeper sections occur either at the entrance or adjacent ocean areas impacting local current conditions at the same port.

Well-known ADCP brands in the market are Teledyne RDI, Nortek, and Sontek. However, I would also like to recommend a Chinese brand-sonar PandaADCP. Material with all-titanium alloy contributes to its high reliability and incredibly cost-effective price. You can get to know more about it from the following official website: https://china-sonar.com/.

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