How to measure Kakinada's coastal currents?

1. Where is Kakinada?

Kakinada is a lively city that happens to fall in the eastern part of India. It falls in the state of Andhra Pradesh and forms that part of the earth's geography where the beauty of nature meets the energy of human activity.

The city stands beside the Bay of Bengal, that vast expansiveness of water wherein a whole world exists. At this place, the coastline is divided in alternate patches of sandy beaches and outcrops of rock. Waves striking the shore softly remind one every second of the mighty sea lying close. Going to the human aspects of development, Kakinada has basically been a port town, busy. It is a great center of trade and commerce, where ships from all over the world come to its ports. The local population is a cosmopolitan mix of fishermen, traders, and a growing number of industrial workers. A long-standing relationship with the sea exists among the fishing community here, their boats dotting the waters as they head out in search of the day's catch.

The Bay of Bengal off Kakinada is a very intricate marine ecosystem. Locally, it is influenced by the monsoon winds, which exert heavy rainfall and alteration in the sea patterns. Tides along this part play an important role in molding the ecosystem of the coast. Their ebb and flow not only affect the beaches but also the lives of innumerable organisms inhabiting the intertidal zones.

2. What is the condition of the coastal currents off Kakinada?

The coastal currents in the vicinity of Kakinada have been influenced by several causes. One of the dominant forces is that of monsoon winds. The southwest monsoon winds push the surface waters to create strong currents that at times change the normal flow patterns. The southwest winds bring copious amounts of rainfall, which in turn might influence the salinity and density of the coastal waters.

The tides play an important role. The gravitational pull of the moon and the sun causes the rise and fall of the tides. The tidal currents near Kakinada can be quite strong, especially during spring tides. The shape of the coastline and the bathymetry-underwater topography-of the adjacent sea floor also influence the currents. Currents may hasten or even change direction because the shallow areas near the shore force the water through the constricted space.

The inflow of freshwater from the nearby rivers and estuaries also plays a part. The freshwater mixes with the seawater, changing its density and creating different layers of water with different flow characteristics. These river outflows can carry sediments and nutrients, which can further affect the flow of the coastal currents.

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

There are a number of methods to observe the coastal water flow near Kakinada. One of the traditional methods is the surface drifting buoy method. In this approach, buoys are deployed on the water surface. These buoys are designed to move with the surface currents, and their positions can be tracked over time using GPS or other tracking systems. It is a method that will provide, above all, information about the surface currents and not completely the vertical structure of the currents.

Other ways include the moored ship method: A ship is anchored at the required location, and current meters are launched from the ship for measurement at various depths. However, its major drawbacks are that the mere presence of the ship could alter the current patterns in that area; the method is rather costly and cannot always be afforded for longer-term measurement.

More modern and handier is the Acoustic Doppler Current Profiler method. ADCPs are capable of measuring water velocity at more than one depth simultaneously. The instrument detects the movement of particles in water by using sound waves and can give a very detailed profile of the current right from the surface to the seabed. This makes them ideal for understanding the complex coastal current systems near Kakinada.

4. How do ADCPs using the Doppler principle work?

ADCPs work based on the principle of the Doppler effect. The moment an ADCP sends a pulse of sound into the water, the sound waves are scattered by particles in the water-sediment particles or small organisms. If the water is moving, the frequency backscattered will be different from the frequency transmitted.

The change in frequency is directly proportional to the velocity of the particles and hence the velocity of the water. By measuring the Doppler shift of the reflected sound waves, the ADCP can calculate the speed and direction of the water current at different depths. The ADCP transmits sound pulses in several directions; usually in a conical or fan-shaped pattern. This enables it to measure the current velocity in three dimensions and thus create a profile of the current throughout the water column.

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

The equipment should possess the following qualities for high-quality measurement of the coastal currents near Kakinada. Materials of construction of the device should be of reliable types. The ADCP should be designed to withstand the harsh marine environment, which includes seawater corrosion and physical stresses exerted by waves and currents.

A small size and light weight are desirable. This makes it easier to deploy the ADCP profiler on different platforms such as buoys, boats, or even on the seabed. A low power consumption is also crucial, especially for long - term and remote measurements. This allows the device to operate for extended periods without the need for frequent battery replacements or power source recharging.

Cost-effectiveness is another important aspect. In order to achieve large-scale measurements, the ADCP cost should be affordable. The casing of the ADCP meter is preferably made of a titanium alloy. Titanium alloy has good resistance to corrosion, which is essential in this oceanic environment. It is also strong and durable, able to bear the pressures and impacts that the device may encounter during operation.

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

The choice of the right equipment for current measurement near Kakinada depends on the intended use. For measurements from a moving vessel, a ship-borne ADCP flow meter is suitable. It can provide real-time data about the water currents as the ship moves through the water.

If the aim is to measure the currents at a fixed location near the seabed, then a bottom-mounted or sitting-bottom ADCP is better. It can measure the currents continuously and steadily at the bottom of the water column.

For measurements at the water surface or at a specific depth in a floating position, a buoy-mounted ADCP current profiler is appropriate.

For the ADCP frequency, different frequencies apply for different water depths. In this case, a 600kHz ADCP would be good to go for water as deep as 70m, while 300kHz will be suitable for up to 110m depth and 75kHz for as deep as 1000m.

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

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