ADCP Application for Measuring Ocean Current in Port Nolloth

1. Where is Port Nolloth?

Port Nolloth is located along the west coast of South Africa. It is a port of important magnitude that has become very instrumental in local and regional maritime activities.

Port Scale and Throughput

The port is of medium scale. It can handle several vessels ranging from fishing vessels, small to medium-sized general cargo vessels, and small coastal vessels. In addition, regarding throughput, it mainly concerns with fishery-related commodities: it deals with the catch mainly by local fishing fleets or fishing fleets calling at each facility. It also conducts general cargo, such as machinery of mines and ores found in mine areas nearby the terminals. Essentially, this port sits on a strategic location that offers a very excellent position for the cargo transport between coastal and hinterland regions.

routes And Cargo

Port Nolloth connects to other routes in its neighborhood along the sea route through the South African coastal line and has trade business with other African countries amongst others. The main port business is fishing as the established fishing community depends on the port facilities for the docking and offloading of catch. Mining companies export minerals from the port apart from the importation of machinery needed in the processes. Besides, there is a little coastal trade that occurs for things like building material and consumables.   Port Management and Operation

A combination of local authorities and private entities manages the port. It is mainly managed to ensure the safety and efficiency of shipping operations. Facilities are maintained to be able to address the various needs of different vessels. There are berths with appropriate mooring and loading/unloading equipment. Navigation aids are in place to guide ships safely in and out of the port.

Port Facilities and Waterway

Facilities include a quay with berths for vessels of various sizes, storage areas for fish alongside other cargo, and maintenance of the waterway leading to it to a suitable depth for the local vessels. It provides a reasonably sheltered environment, but the impact of ocean currents on navigation and operations remains a consideration.

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

Navigation Safety

The measurement of the ocean currents at Port Nolloth is vital from the point of view of navigation safety. With fishing boats, cargo ships, and many other vessels, it is important to know the current conditions accurately. Currents can take a ship off course and affect the speed. For example, a good lateral current at the entrance can shift a fishing boat off its course, where it can easily collide with other boats or port structures. Precise measurement of currents allows ship captains to make informed decisions while approaching and leaving the port for safe passage.

Optimization of Port Operations

Knowing how currents function can be helpful to bring up port operations. Fishermen in fishing vessels will thus, be able to effectively and systematically schedule their trips. Since these also act as carriers of nutrients, hence fish, knowing currents enables them to locate highly productive fish catch areas. In the handling of cargo, for instance, this flow can affect operations when loading or unloading from vessels. Favorable current conditions will, thus, aid in the vessels approaching to dock, thereby saving precious operation time.

Ecosystem and Environmental Management

Currents have much to do with the distribution of nutrients and transportation of marine organisms in the catchment area of the facility. In fact, a measurement of ocean currents offers the ability to understand the local ecosystem. This can further be utilized in the management of the environmental protection of the facility by foreseeing the dispersion of any pollutants or how currents might affect the spawning and nursery areas of fish.

It is more sophisticated and handy in measuring currents compared to the traditional techniques. It enables real-time and accurate data gathering, which is very key in the proper functioning and management of Port Nolloth.

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

ADCPs rely on the principle of Doppler for operation. The ADCPs transmit acoustic signals into the water. Acoustic waves transmitted by it interact with moving particles in the water, which include suspended sediments, plankton, or even small organisms. If such particles are in motion, then the reflected acoustic waves will experience a shift in frequency due to the Doppler effect.

This frequency shift is measured by the Acoustic Doppler Current Profiler(ADCP), which calculates from it the velocity of the moving particles. Since this movement of the particles somehow has something to do with the ocean current, then the ADCP would now have an estimate of the speed and direction of the ocean current.

Ship - borne ADCP in Port Nolloth

An ADCP is mounted on a ship-borne device when used in the port area. The ship moves across the waters of the port area with the ADCP sending acoustic signals at close intervals downwards and sideways. It continuously picks up the data of the ocean currents at different depths and positions as the ship is on the move. This provides the basis for comprehensive coverage of the current situation over wide areas in the port.

Fixed ADCP in position Port Nolloth

It is usually fixed at a certain location in the port, such as on a pier or submerged structure. The fixed ADCP monitors the ocean currents that pass by its position. A fixed ADCP gives long-term, stable current data at a particular area of the port, good for analyzing the regular patterns and changes of the currents within that particular location.

4. What is needed to have a quality measurement of Port Nolloth currents?

Material Reliability 

Equipment must be highly material reliable for high-quality current measurement in Port Nolloth. The environment of the port is so hostile that the equipment suffers from saltwater exposure, which is corrosive, and possible mechanical impacts. Hence, equipment should be fabricated from durable materials that would be able to put up with such conditions and provide long-term, accurate measurement processes.

Small in Size, Light in Weight, Low Power Consumption 

Preferably of smaller size, lower weight, and lower power consumption. An ADCP of small size can easily be installed in various places at the port, both onboard ships and on fixed constructions. A light-weight device allows for easier transportation and facilitates the installation process, reduces labour, and costs accordingly. Low power consumption allows it to keep working for an extremely long time without changing the batteries frequently or consuming high energy, which is an important issue for the long-term uninterruptible measurement of the current.

Cost-effectiveness Cost-effectiveness is also an important factor. To enable large-scale measurement of the ocean currents in the port, the equipment should have a reasonable cost. The ADCP casing should be made of titanium alloy. The use of a titanium alloy has several advantages: It has very high strength which is able to resist pressure and other mechanical forces underwater that this equipment is likely to face in a port environment. Besides, it has excellent corrosion resistance that guarantees seawater corrosion will not have a great impact for quite a long time. In addition, being lighter in weight compared with any other material, the equipment can be installed within a more feasible port range.

5. Choice of Proper Equipment Based on Current Measurement Needed

Based on Function Use In Port Nolloth, current measurement shall be done with appropriate equipment depending on the particular purpose of use. The intention may be to do mobile measurements while the ship is navigating in the port, for which the ship-borne ADCP will be applied. In this case, the areas of the port will be covered when the ship has moved around, giving a complete overview of the current situation.

For long-term fixed-point monitoring of a given area in the port, a sit-on-bottom ADCP will be more appropriate. It rests at a certain position and continuously monitors current conditions, which is useful in drawing valuable data from the analysis of local current patterns.

If the need is to monitor a wider area on the water surface with some mobility, then the buoy-mounted ADCP may be considered.

Based on Water Depth Besides, the frequency of the ADCP also should be chosen according to the water depth. In general, for water up to 70m in depth, a 600kHz ADCP normally will provide current profiles in shallower waters quite accurately, while the 300kHz ADCP is best suited for about 110m and the 75kHz for much deeper waters of up to 1000m for reliable current measurement results.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese ADCP brand - China Sonar PandaADCP is also worth mentioning. It is made of all - titanium alloy material, combining excellent durability and corrosion resistance with an incredible cost - performance ratio. You can find more information about it on its website: (https://china-sonar.com).

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