How to measure the coastal currents of Konarak?

1. Where is Konarak?

Konarak is a small town in Odisha, India. It is on the eastern coast of the country through the Bay of Bengal. That place is very famous because of the history and architecture related to the place.

It has a reputation in housing the famous Sun Temple of Konarak, which is in the list of UNESCO World Heritage Sites. Thousands of tourists visit it from every part of the globe due to its intricate carvings and its gigantic size. It has its root deep in the traditions and religious belief of Konarak. Local people mainly indulge in agriculture, fishing, and handicraft works associated with tourism in the temple.

Lying next to it, the Bay of Bengal represents a huge body of water, quite significant both in the local ecology and economy. Richly diverse marine life inhabits these coastal waters, like various fish, prawns, crabs, and many species of shellfish. The sea itself controls the weather to some degree since sea breezes and occasionally cyclones are a feature of the weather pattern in the area. The coasts along Konarak are the sandy beaches that are eaten away sometimes by the action of waves and currents.

2. What is the condition of the coastal currents near Konarak?

The currents in the immediate vicinity of Konarak are controlled by many factors. Tidal currents form one significant component. Because of the gravitational pull of the moon and the sun, tides are experienced in the Bay of Bengal, and the accompanying tidal currents may be pretty strong. The coastline shape with its embayment and promontories can also alter the flow of such tidal current movements.

Besides that, the contribution of the monsoon winds is huge. The southwest monsoons from June to September and northeast monsoons from October to December have strong winds capable of driving the surface waters. These could alter the direction and speed of the coastal currents and result in the formation of different patterns. The inflow of freshwater from the nearby rivers, while mixing with seawater, affects the density-driven currents.

The Bay of Bengal coastal water flow may interact with large-scale ocean circulation patterns in this region. Inflow from other regions brings about different water masses and changes in the temperature, salinity, and overall characteristics of the currents.

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

Surface Drift Buoy Method: This is a method where buoys are deployed on the water surface. These buoys are designed to drift with currents. Further, if satellite-based tracking systems or any other system of positioning is used to track the movement of such buoys over time, it would essentially be information pertaining to direction and speed of surface currents. However, with this approach, one largely gets the data for the surface layer. This may not give us comprehensive knowledge of currents at different depths.

Anchor Boat Method: In this, a boat is anchored in the waters off the coast. From it, instruments record the water flow at various depths. It is a labor- and time-consuming method but does have the potential of collecting data on flow that may be rather more detailed than around the location of the anchored boat. Besides, this is only applicable over a limited area.

ADCP Technique: Being more advanced and much faster than the previous technique, it measures coastal currents with efficiency. It works on a principle that uses sound waves in order to measure water's velocity at multiple depths all at once. This would develop an appropriate depth profile from surface to a certain depth in the current by emitting a series of pulses in the water and analyzing the Doppler - shifted reflections from particles in the water. This will be a better and complete representation of the currents along the coast than the other two discussed methods.

4. How do ADCPs applying the Doppler principle work?

The ADCPs use the Doppler effect to operate. They send pulses of sound into the water. These sound waves, if they interfere with particles in the water-sediment particles, plankton, or other small organisms-the frequency of the reflected sound waves changes through the Doppler effect. When the particles are moving towards the ADCP profiler, the reflected waves have a higher frequency than the emitted waves; when they are moving away, the frequency is lower.

The instrument calculates the velocity at different directions by measuring the frequency shifts of reflected sound waves at different angles and depths. An ADCP current meter uses multiple transducers that send and receive these sound signals, thus enabling detailed profiling of the water velocity throughout the water column from the surface to a certain depth according to the instrument's capability.

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

The equipment to be used for high-quality measurement of the coastal currents near Konarak should be made of reliable materials. Since the marine environment is very harsh, with saltwater corrosion, temperature fluctuations, and even physical impacts from floating debris, the equipment needs to be robust.

The size of the equipment should be small, which would make the processes of deployment and installation more feasible. A small size is practical for handling and installation whether deployed from boats, buoys, or at the seabed; it also makes transportation and maintenance easier.

The weight of the equipment should be light, especially for floating or moored devices. A light weight is important for proper buoyancy and stability. The power consumption must also be low to enable continuous operation over long periods without frequent battery replacements or a large power supply.

Another important consideration is cost-effectiveness. The equipment should be affordable to take large-scale measurements along the coast. A casing made of titanium alloy would be an excellent option for ADCPs. Titanium alloy provides very good resistance to corrosion, which is a key requirement in the salty marine environment. It is strong and relatively lightweight, meeting the requirements for high-quality current-measurement equipment.

6. How to Choose appropriate equipment for current measurement?

The equipment for the measurement of current at Konarak shall be selected by first considering the purpose of use.

Ship-borne ADCP: It is ideal for measurement from a moving vessel. The ship while cruising along the coast can continuously record the coastal currents thus recording a series of data over a relatively wide area as covered by the ship route.

Bottom-mounted ADCP: For all fixed-point measurements from the seabed, in particular suitable. This yields a very stable and long record of the water flow close to the bottom, something that is in particular requested with respect to the understanding of the interaction between the bottom topography and the coastal currents.

Buoy-mounted ADCP: Used when the purpose is to measure currents in a given area over a longer period while floating on the water surface. It can be deployed in areas of interest and provide continuous data without requiring the vessel to be present all the time.

In terms of frequency, a 600kHz ADCP will suffice for water depths within 70m. For those as deep as 110m, it is better to use a 300kHz ADCP. A 75kHz ADCP can reach as deep as 1000m of water.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar ​PandaADCP, is also worth mentioning. It has a casing made entirely of titanium alloy and offers an excellent cost-performance ratio. You can find more information about it at ​https://china-sonar.com/.

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