How to measure the Vizianagaram coastline currents?

1. Where is Vizianagaram?

Vizianagaram is a city in the state of Andhra Pradesh, India. Vizianagaram is located in a state that has been steeped in history and resplendent with cultural traditions. Its backdrop consists of rolling hills and fertile plains. It is that place where ancient architecture co exists with modern infrastructure.

Geographically, Vizianagaram is fairly near the coastline of the Bay of Bengal. The nearby coastal areas are a mix of sandy beaches and estuaries. The estuaries here are formed by the meeting of several small rivers and the sea. These waterways are important not only for local fishing but also as a habitat for a wide variety of flora and fauna. The Vizianagaram coastline is also one of the places preferred by tourists due to the beauty of beaches and the coastal culture to be experienced here. These waters of the Bay of Bengal represent a marine ecosystem, stretching beyond the shoreline into great distances and influenced by oceanic currents and weather patterns across the Indian Ocean.

2. What is the situation of the coastal currents near Vizianagaram?

The coastal currents near Vizianagaram are influenced by many factors. The monsoon winds are one of the most predominant forces. The southwest monsoon brings strong winds that can drive the surface currents and change their direction. The freshwater contribution of rivers that empty into the Bay of Bengal near Vizianagaram contributes to changes in the density and salinity of the coastal waters. These changes in density could, in turn, form layers of water and affect the movement of currents.

Tides are also a major factor. The tidal range in the Bay of Bengal off Vizianagaram can be quite dramatic, with considerable changes in the water level and the flow of the coastal currents. The gravitational pull of the moon and the sun results in a semi-diurnal tidal pattern, with two high tides and two low tides each day. These tidal currents mix the water masses and influence the overall circulation of the coastal waters. Besides, the large-scale ocean-current patterns of the Indian Ocean can have their impact on the coastal currents of this place. This means that the mere presence or movement of the Indian Ocean Gyre can affect the water mass to reach the Vizianagaram coast.

3. How to Observe the Coastal Water Flow of Vizianagaram?

Surface Drift Buoy Method: Some buoys called Surface Drift Buoy were installed on the surface of the water. These buoys are designed to follow the movement of the surface currents. Their positions are tracked over time using satellite-based or other positioning systems. The movements of these buoys would provide information on the direction and speed of the surface currents. However, this satellite method can only provide data from the surface layer and does not allow any complete insight into currents within the entire water column.

Anchor Ship Method: A ship is anchored in the water at the coast of Vizianagaram. Then, with the help of some instruments, the flow of water around the ship is measured at different depths, which permits a more detailed analysis of the vertical profile of the currents. But the drawback with this method is that the ship will be subjected to waves and wind, hence the measurements may include errors.

ADCP Method: More advanced and convenient, it makes use of sound waves in measuring the velocity of water at multiple depths simultaneously. The current speed and direction are provided in detail from the surface to the seabed. Having a high degree of accuracy and the ability for continuous data collection, this is an increasingly popular option for the study of currents along coastlines.

4. How do ADCPs using the Doppler principle work?

ADCPs are based on the Doppler principle. They send acoustic pulses into the water. If these sound waves encounter moving particles in the water-like sediment or small organisms-the frequency of the reflected waves shifts due to the Doppler effect. This frequency shift is measured by the ADCP profiler. It knows the characteristics of the emitted sound waves and, by analyzing the frequency changes in the received signal, can calculate the velocity of the water at different distances from the instrument. Several acoustic beams are usually combined in an ADCP current meter to get an accurate representation of the three-dimensional flow field. This will allow the ADCP to paint a detailed picture of the currents in the coast, which would include the horizontal and vertical movements of the water.

5. What is needed for high-quality measurement of Vizianagaram coastal currents?

The equipment for high-quality measurements of the coastal currents at Vizianagaram must possess certain qualities, first of all. The materials it will be made from should be reliable due to the harsh marine medium: seawater corrosion, high humidity, and exposure to waves and storms - equipment should be resistant to these environmental factors.

The equipment should be small in size and light in weight, which makes deployment easy whether on buoys, ships, or at the seabed. Low power consumption allows for longer-term operation without the need for frequent battery changes or a complex power supply system in remote locations. Cost-effectiveness is another important factor as it enables more extensive deployment for comprehensive monitoring.

The casing of the ADCP current profiler is made from a material preferred to be made of titanium alloy. In most applications, especially in Vizianagaram's neighboring seawater environment, there will be a very remarkable ability for corrosion resistance. It is strong and resilient, able to resist mechanical stresses by waves and water pressure. Besides that, considering the relatively low density than that of some other strong metals, it is suitable for uses related to equipment that should have less weight while keeping their strength as such.

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

The usage scenario has to be considered in choosing the right equipment for the measurement of current near Vizianagaram. If the measurements are to be ship-based, then a ship-borne ADCP would be appropriate. These can be mounted on the hull of the ship and measure the flow of water as the ship cruises along the coast.

Sit-on-bottom ADCPs are ideal for fixed-point measurements at the seabed and can provide long-term data on the currents at a specific location.

Buoy-mounted ADCPs are useful for monitoring surface and subsurface currents while floating in the water.

Frequency-wise, up to a water depth of 70m, the 600kHz ADCP is normally the better choice for shallow waters due to its high-resolution data; up to 110m, it is 300kHz ADCP, and for depths up to 1000m, it would require a 75kHz ADCP for assured measurement all over the water column.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is highly recommended. It is made of all-titanium alloy material, ensuring its durability and reliability in the marine environment. It also offers an excellent cost-performance ratio. You can visit its website: https://china-sonar.com/ for more information.

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