How to Measure the Coastal Currents of Balasore

1. Location and Overview of Balasore

Balasore is a coastal town in the state of Odisha, India. It's located along the Bay of Bengal and is known for its beaches and historical significance.

The local economy is supported by fishing, agriculture, and some small - scale industries. The Bay of Bengal near Balasore is rich in marine resources such as fish, prawns, and other shellfish. Fishing is a major activity for the local population.

2. The Situation of Coastal Currents near Balasore

Tidal Currents

The tides of the Bay of Bengal significantly affect the coastal currents of Balasore. The tides in this region are semi-diurnal, with two high tides and two low tides each day. The tidal range may lead to the development of strong and variable tidal currents. Such currents can change direction and speed according to the phase of tide and the local topography.

Monsoon Influence

The monsoon winds, on the other hand, also play an important role. During the southwest monsoon, from June to September, strong winds blow from the southwest towards the coast. These winds can drive surface currents and bring about considerable changes in direction and speed of the coastal currents. Northeast monsoon, from November to February, winds also blow from the northeast direction.

Underwater Topography

The coastal currents around Balasore are influenced by the underwater topography. The existence of sandbars, shoals, and channels will result in the variation of the path and speed of the current. For instance, a sandbar may decelerate the current and bifurcate it, while a channel may accelerate the current by channelizing it.

3. Methods to Observe the Coastal Water Flow near Balasore

Surface Drifting Buoy Method

Principle: A buoy drifting on the surface is launched in water to measure the current at the surface. Its path is followed over a time using GPS or other tracking systems.

Advantages: It is relatively simple and inexpensive means to initially understand the surface current patterns. The data obtained may be used to obtain information about the direction and speed of the surface current during different times of the day and in various weather conditions.

Limitations: This method only provides information about the surface current. Wind and waves can have a significant impact on the buoy's movement, leading to inaccurate measurements of the current's direction and speed. For example, during a storm or strong winds, the buoy may not accurately represent the actual current.

Anchor-Boat Method

Principle: An anchored boat is used for the measurement of the current. Instruments are lowered from the boat into the water to measure the current at different depths.

Advantages: It allows more detailed depth - wise measurements of the current. By using instruments such as current meters, a better understanding of the vertical structure of the current can be obtained.

Limitations: The area of measurement is restricted by the fixed position of the boat. It may not be able to capture the full variability of the currents in a large coastal area. Also, the boat may be subjected to waves and tides, which may introduce errors in the measurement.

Acoustic Doppler Current Profiler (ADCP) Method

Principle: ADCPs emit acoustic signals into the water and measure the Doppler shift of the reflected signals to calculate the velocity of water at different depths.

Advantages: This provides a more comprehensive profile of the current from the surface to the seabed. ADCPs are less affected by surface disturbances and can operate continuously for long periods, giving a more accurate picture of the current structure.

4. How ADCPs using the principle of Doppler work

ADCPs work on the principle of the Doppler effect. They transmit high-frequency acoustic pulses into the water. When these pulses interact with moving water particles, the frequency of the reflected pulses changes. If the water particles are moving towards the ADCP current profiler, the frequency of the reflected signal is higher than the emitted signal, and if they are moving away, it is lower.

It includes an array of multiple ADCP transducers that work by the sending and reception of signals with displacements based on specific angles. Making calculations by changing the Doppler from all various directions, different depths provide the determination of three-dimensional velocity the water flows, the horizontal component, the vertical components of the said velocity which determines the characteristics of current, as well as its structures and behaviors in detail.

5. High-Quality Measurement of Coastal Currents near Balasore: Requirement

Materials

The equipment should be made of reliable materials for high-quality measurement of the coastal currents near Balasore. A durable casing will be required because of the marine environment, with saltwater, potential exposure to storms, especially during the monsoon season, and the influence of tides and ocean currents. The size of the equipment should be small for easy deployment and retrieval, considering the rough sea conditions at times and the presence of beaches and other coastal structures.

Design Considerations

A light weight design is preferred as it makes the equipment more manageable during installation and maintenance. Low power consumption is required for long - term and autonomous operation. Cost - effectiveness is also important to enable large - scale measurements, considering the local economic and resource constraints.

Casing Material for ADCPs

The casing of ADCPs is preferably made of materials with excellent corrosion resistance, such as titanium alloy or high-grade stainless steel. These can withstand the corrosive effects of seawater. They are also strong and durable to hold up against the pressure of the water at different depths. Their lightweight nature-especially titanium alloy-makes them more convenient for various deployment methods.

6. How to Choose the Right Equipment for Current Measurement near Balasore

Purpose-Based Selection

When choosing equipment for current measurement near Balasore, consider the purpose of use first. In cases where the measurement is for vessel navigation or short-term research on surface conditions, such as those used by local fishing boats, a ship-mounted ADCP meter or a simple surface-drifting buoy system may be adequate. While the ship-mounted ADCP will be able to provide current information in real time during the voyage, the buoy can provide some general idea about the surface current.

Seabed-related measurements would be better served by a bottom-mounted ADCP flow meter for studies in the near-bottom region for sediment transport, which is of importance here given the sandy beaches and potential coastal erosion, or benthic ecology. The bottom-mounted ADCP can resolve the structure of the near-bottom current that is responsible for the transport of sediment and its effects on the seabed and the beach.

For any long-term and wide-area monitoring of the coastal current, it is ideal to use a buoy-type ADCP current meter, for which continuous data may be obtained over an extended period for relatively large areas. This would help to decipher the overall patterns and their changes in the coastal currents.

Frequency Consideration for ADCPs

Considering the ADCPs frequency, for water depths up to 70m, which would be adequate for most of the coastal area around Balasore, a 600kHz ADCP is an excellent option. For deeper waters that may occur in some areas offshore or in channels, a 300kHz or even lower ADCP, depending on the depth, would be suitable. The choice of frequency also depends on the specific requirements of the measurement, such as the level of detail needed for the current profile and the trade -off between accuracy and range.

There are well-known brands of ADCPs such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost-effective option with good quality, the China Sonar PandaADCP is highly recommended. It is made of all-titanium alloy material and offers an incredible price-performance ratio. You can find out more about it on its website: https://china-sonar.com/.

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