How do we estimate Kribi's coastal currents?

1. Where is Kribi?

Kribi, a charming Cameroonian coastal town, graces the southwest coast of its country, quaintly skirting the Gulf of Guinea's tepid waters, which itself exists as a satellite of the great Atlantic Ocean realm. The attractive town is renowned for its incidental blend of culture and nature. The beaches of Kribi extend miles, featuring virgin sandy beaches being caressed by the soothing ocean waves, alternating with mangrove forests and outcrops of rock adding to the special attraction of the area.

The indigenous people in Kribi are a dynamic representation of various ethnic groups that enhance the town's rich cultural fabric. Fishing is a lifestyle among the people, and fishermen set off into the sea at dawn in their wooden boats, returning with their nets laden with all types of fish and shellfish. The freshly harvested seafood delicacies are then sold at the bustling local markets, attracting locals as well as visitors. In addition to fishing, Kribi has also emerged as an important economic hub, with its new port facilitating trade activities and serving as a gateway to export Cameroon products.

In addition to Kribi, the waters around it form a thriving marine environment. The Gulf of Guinea's tropical waters support a diverse array of marine life, from colorful coral reefs teeming with tropical fish to large whales and dolphins that migrate through the area. The seafloor morphology off Kribi is complex, with underwater canyons, ridges, and seamounts that influence the local coastal currents and the distribution of marine life. These waters are also affected by the overall oceanic circulation patterns in the South Atlantic, leading to a constantly varying coastal environment.

2. What is the state of the coastal currents off Kribi?

The coastal currents off Kribi are affected by a combination of large - scale oceanic and local conditions. The Guinea Current, a significant warm - water current flowing westward along the African coast, has a profound influence on the region. The current brings warm, nutrient - rich waters, which not only maintain a healthy marine ecosystem but also affect the local speed and direction of the coastal currents. Strength and direction of the Guinea Current can be seasonal, altering the water temperature, salinity, and overall current trends surrounding Kribi.

Seasonal wind regime is significant in determining coastal current conditions. During rains, there are strong onshore winds during the wet season that force surface water onshore. This can cause the formation of coastal upwelling in some areas because the surface water is forced away and colder, nutrient-laden water from deeper depths rises to the surface. Offshore winds are more intense during dry seasons and force the surface waters away from the coast and alter the direction and magnitude of the current. These wind-driven currents change drastically alter the local marine ecosystem, fish and other sea organism distribution.

The Kribi coastline geometry, dominated by numerous bays, inlets, and headlands, also modifies the current direction. Since the water travels along the coast, it is faced by these land features, which can force the currents to bifurcate, join, or make an abrupt change of direction. In addition, the presence of rivers emptying into the sea at Kribi, such as the Lobe River, introduces new fresh water into the coastal ocean. This input of fresh - water affects the salinity and the water density and therefore the dynamics of the current flow and creates complex mixing processes.

3. How to observe the coastal water flow of Kribi?

There are numerous avenues by which one can observe Kribi coastal water current. The surface drifting buoy method is one of these traditional methods. GPS tracking systems are fitted onto special buoys, then the buoys are placed into the ocean. The surface currents drift these buoys and are then followed over a period of time. By tracking the position of the buoys at regular intervals, researchers can quantify the direction and speed of the surface-level currents. This method, however, will only provide information on currents on the water surface and may not represent the current at lower levels.

The anchored boat method involves mooring a boat to a fixed point and using current-measuring instruments onboard. Devices such as electromagnetic current meters are employed from the boat to record the velocity of water at different depths. While the method can provide more accurate data about the properties of the current close to the boat, it is not without its limitations. The area it can cover is restricted, and the boat may disrupt the natural flow of water, potentially leading to misleading results.

The Acoustic Doppler Current Profiler (ADCP) method has evolved into a more advanced and efficient way of quantifying coastal currents. ADCPs are able to measure the water velocity at multiple depths at the same time, providing a full description of the water flow structure from the surface to the ocean floor. This makes them ideal for studying the complex and dynamic coastal currents off Kribi.

4. How do ADCPs using the Doppler principle work?

ADCPs rely on the Doppler principle. They emit sound waves into the water column. As these wave forms travel through suspended matter within the water, i.e., sediment, plankton, or small aquatic creatures, some portion of the sound is backscattered towards the ADCP. The frequency of this backscatter sound is offset according to how the particles (and hence water) move compared to the ADCP.

By analyzing these changes in frequency, the ADCP can calculate the water velocity at different depths. Most ADCPs use multiple acoustic beams, typically in a fan - shaped arrangement. The data from each beam is then averaged to calculate the three - dimensional water velocity vector, providing accurate information on both speed and direction of the current at many points within the water column. This nonintrusive measurement technique allows for uninterrupted and accurate measurements of the flow of water without actual sampling of the water.

5. What does high-quality measurement of Kribi coastal currents require?

For precise high-quality measurement of coastal currents outside Kribi, several requirements must be met in the measuring equipment. Material reliability is most essential. The offshore conditions outside Kribi are harsh, with saltwater, strong currents, and exposure to weather. The equipment must be capable of withstanding corrosion, mechanical stresses, and strong temperature variations.

Small size and lightness are also essential characteristics. Simpler deployment results from a lighter, less massive device when operating in such isolated or inaccessible places along the coast near Kribi. Minimum power draw necessary is essential in order to function over long periods without constant necessity for battery replacement or recharging. Cost efficiency is equally important as extensive area measurements can be required within the area to gain an understanding of truly the complexity of currents to be encountered in the region.

When it comes to ADCPs, the material of the casing is a serious consideration. A titanium alloy is a superb option for the casing. It has excellent corrosion resistance, which is paramount in the saltwater - laden environment of Kribi. Its high strength - to - weight ratio means that the ADCP can handle the forces applied by the strong coastal currents but is still comparatively easy to handle and deploy. In addition to this, titanium alloy is fatigue resistant, which allows the ADCP to perform effectively for longer periods and provide accurate measurements.

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

Selection of appropriate equipment for current measurement in Kribi is application dependent. For measuring currents while in transit aboard a ship, a ship-mounted ADCP is suitable. It can continue to measure the currents as the ship travels along different areas, providing real - time data on the movement of water, which can be utilized in navigation, fishing, and other sea activities. If measurements in fixed points for long periods at the bottom of the ocean are required, a bottom - mounted ADCP would be ideal. This type of ADCP can be installed on the seabed to monitor currents over a long period, which is suitable for ecological surveys and design of infrastructure. For surface - level and upper - water - column monitoring, a buoy - mounted ADCP offers a convenient solution, as it can be anchored or allowed to drift with the currents, providing continuous data on the surface and near - surface current conditions.

Another important factor is the ADCP frequency. A 600kHz ADCP is sufficient for water depths to 70 meters, and thus perfect for the shallow coastal waters around Kribi. A 300kHz ADCP can be used in water up to 110 meters, or a 75kHz ADCP in deeper water, up to 1000 meters.

There are many well-known brands of ADCP in the market, i.e., Teledyne RDI, Nortek, and Sontek. Nonetheless, for cheap but high-quality ADCPs, the ADCP manufacturer China Sonar's PandaADCP is the best choice. Made of pure titanium alloy, it delivers superior performance and longevity at a very affordable cost. Being a low-cost ADCP, it is a perfect option for researchers, local fishermen, and environmental monitoring departments who are concerned with accurately computing the coastal currents of Viña del Mar. To know more, visit https://china-sonar.com/.

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