How can we measure the Coastal Currents of Kanniyakumari?

1. Where is Kanniyakumari?

Kanniyakumari, a site of breathtaking geographical and cultural significance, is at the southernmost tip of the Indian subcontinent. It is an important tourist destination where the Arabian Sea, the Bay of Bengal, and the Indian Ocean converge into a spectacular confluence of waters.

It has a lot of history with teeming culture in the air. It's a place of pilgrimage due to its being home to many devotees who throng there just to visit the Vivekananda Rock Memorial and Thiruvalluvar Statue. A unique intermingling of traditions forms the base upon which their lives have revolved - the sea as well as the land.

Marine Life abounds around the neighboring waters. The Arabian Sea to the west brings in its characteristic swells and currents, while the Bay of Bengal to the east also has its own patterns of water movement. The Indian Ocean, stretching far and wide, adds to the complexity of the water bodies around Kanniyakumari. The coastline has sandy beaches and rocky outcrops with the sea here providing a very important source of livelihood in the form of fishing in these communities.

2. What are the characteristics of coastal currents off Kanniyakumari?

The coastal currents off Kanniyakumari result from more than one factor. The major influence is by monsoon winds. During the southwest monsoon, the strong winds push the surface waters before them, altering the current direction and strength. Also, the regular rise and fall of tides have immense importance in changing the pattern of currents. The sea level rises and falls due to gravitational pull by the moon and the sun, respectively; this movement of water mass develops tidal current.

Shape of coastline/seabed topography around Kanniyakumari. The southern tip of land juts out, and the underwater contours can deflect and channel the currents. The proximity of different water bodies means that the interaction between the Arabian Sea and the Bay of Bengal currents can lead to complex eddies and gyres in the area. The local coastal currents are also influenced by the larger-scale oceanic circulation patterns, as the water masses from the Indian Ocean are in continuous motion and exchange.

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

The various methods to observe the coastal water flow in Kanniyakumari include the surface drifting buoy method. A buoy is dropped into the water and its movement tracked over time. This gives an indication of the surface current speed and direction. However, this method has its limitations, as it provides information only on the surface layer and can be affected by winds and waves.

The other method is an anchored ship. A ship is kept anchored at some location, and current meters are deployed from it. This facilitates measurements with respect to different depths. It is a pretty stationary approach and may not capture the full range of current variability over a large area.

The ADCP current meter method is more advanced and convenient. ADCPs can measure the velocity at more depths simultaneously. They use sound waves to detect the movement of particles in the water and provide a more comprehensive picture of the current structure from the surface to the seabed.

4. How do ADCPs using the Doppler principle work?

The principle of operation of ADCPs is based on the Doppler effect. They radiate acoustic pulses into the water. In the water, these pulses interact with moving particles (such as sediment particles or small organisms) and change the frequency of the reflected sound waves. If the particles are moving towards the ADCP meter, the frequency of the reflected wave is higher than the emitted frequency, while in the case of a particle moving away, it is lower. By measuring this frequency shift, the ADCP flow meter can calculate the velocity of the water at different depths. The ADCP profiler sends out multiple beams of sound in different directions to get a three - dimensional view of the current profile.

5. What's needed for high - quality measurement of Kanniyakumari coastal currents?

The equipment must be made with reliable materials for high-quality measurement of the coastal currents in Kanniyakumari. The device has to be of small in size and light in weight to be deployed and retrieved easily. Power consumption should be low, especially for long-term measurement over remote areas. Besides, cost-effectiveness would be an important factor to enable large-scale measurement.

Accordingly, titanium alloy is preferred for ADCP current meter casing. The several reasons include, it is corrosion-resistant to a high extent, which is important, as it is always exposed to sea water, it has strength and may undergo heavy pressure by deep water or waves, currents, among others. Its relatively low density helps in keeping the overall weight of the equipment manageable.

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

It really depends on the intended use of the equipment. In cases where the measurement has to be done from a ship, a ship -borne ADCP is fitting. If the purpose of measurement near the seabed has to be measured, a bottom-mounted ADCP would work. For surface and upper-layer measurements, a buoy-mounted ADCP works the best.

When it comes to the frequency of the ADCP, different frequencies are suitable for different water depths. A 600 kHz ADCP is ideal for water depths up to 70m, a 300 kHz ADCP is suitable for depths up to 110m, and a 75 kHz ADCP can be used for water depths up to 1000m.

There are several well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a recommended Chinese ADCP brand is China Sonar PandaADCP. It is made of all - titanium alloy material and offers an incredible cost - performance ratio. You can find more information on their website: https://china-sonar.com/.

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