How to Measure the Sittwe Coastal Currents

1. Where is Sittwe?

Sittwe is a city that is found in Myanmar, in a state known as the Rakhine State. It is an important coastal city that sits on the Bay of Bengal. The city is an essential port and an active center of economy in this region.

The landscapes around Sittwe are a combination of coastal plains and waterways. The city is fringed by sandy beaches and mangrove forests. The local people engage in different professions such as fishing, trading, and agriculture. The Bay of Bengal alongside Sittwe is immense and dynamic. It is subject to powerful monsoons and strong tidal currents.

The marine life in the waters is so vast and varied. The waters abound with fish, crustaceans, and other living organisms of different kinds. On the one hand, mangrove forests protect the coastline from erosion; on the other hand, they serve as a breeding ground and shelter for many species of fish and aquatic animals. Its location also made it a strategic point for both waterway trade and transport.

2. What about the coastal currents around Sittwe?

There are a number of factors that come into play when describing the coastal currents around Sittwe. The coastal currents are dominated by the monsoon winds. The most significant conditions arise from the strong winds coming from the southwest monsoon, and these winds drive the surface currents. These sometimes continue for months on end and drive shipping and fishing operations.

Tidal currents are also very significant. The Bay of Bengal has extreme ranges of tides, and the tidal falls and rises have enormous consequences in the nature of current patterns, strong and complex. This inflow of freshwater through rivers and estuaries in this region can alter the salinity and density of the waters along the coast, which in turn affects the flow of currents.

Its shape and bottom topography are very important. The sandbars, shoals, and channels make the currents diverge, converge, or form eddies. The interaction between the coastal currents and the larger oceanic currents in the Bay of Bengal further adds to the complexity of the current situation.

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

Surface Drifting Buoy Method: It can estimate the surface current by using a surface-drifting buoy. A buoy is dropped into the water and its movement over some time is tracked, usually with the help of GPS or other tracking devices. This method, though, has a limited usage. It can give information about the surface current alone and is normally easily affected by wind and waves. For instance, a strong on-shore wind might push the buoy towards the shore and give the impression that the current is flowing from some other direction than it actually is.

Anchor - Boat Method: An anchored boat can be utilized in measuring the current. Instruments are lowered from the boat into the water to measure the current at different depths. While this technique can give more detailed depthwise measurements, it also has its disadvantages, the boat remains in a fixed position and can sample the current in only a relatively small area around the anchor point; it may not capture the full variability of the currents in a large coastal area.

Acoustic Doppler Current Profiler (ADCP) Method: This technique is one step ahead and quite efficient for measuring the currents along the coast. ADCPs send out acoustic signals into the water and, based on the reflected signal's Doppler shift, measure the velocity of the water at different depths. This gives a better profile of the current all the way 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 do ADCPs using the Doppler principle work?

ADCPs operate on the principle of the Doppler effect. They send high-frequency acoustic pulses into the water. In this process, when these pulses encounter moving water particles, the frequency of the pulses that get reflected back changes. If the water particles move towards the ADCP profiler, the reflected signal is of a higher frequency than the one emitted and vice-versa if the particles move away.

The ADCP meter is fitted with multiple transducers that transmit and receive signals at different angles. By analyzing the Doppler shifts from different directions and at different depths, the device is able to calculate the three-dimensional velocity of the water. This means it can compute the horizontal and vertical components of the velocity, hence giving an in-depth understanding of the structure and behavior of the current.

5. What do Sittwe coastal currents require for high-quality measurement?

The equipment to measure the coastal currents in the vicinity of Sittwe needs to have reliable materials. The marine environment is very harsh due to saltwater, much humidity, and exposure to storms most of the time. Thus, it must be casings that are durable. The size of the equipment should be small enough to allow easy deployment and retrieval, particularly in cases when the coasts are in a complicated landscape.

It should have a lightweight design, since it is easy to handle by the equipment during installation and maintenance. It has to ensure low power consumption for long-term autonomous operation. Besides, it should be cost-effective to enable large-scale measurements.

The casing of ADCPs is preferably made from Titanium alloy. The Titanium alloy has excellent corrosion resistance, which is very much essential to withstand the corrosive action of sea water. It should also be robust and lasting to bear the pressure of water at different depth. The light weight makes it easier in a number of deployment methods.

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

The purpose of use should be considered first when choosing the equipment for current measurement. In the case of measurement for navigation of a vessel or short-term research, a ship-mounted ADCP flow meter is suitable. It provides real-time current information during the voyage.

For near-seabed measurements, such as the study of sediment transport or benthic ecology, the bottom-mounted ADCP current profiler is preferred since it has the ability to capture details of the near-bottom current. If long-term and wide-area monitoring of coastal currents is required, a buoy-type ADCP would be ideal.

Frequency of ADCPs: For water depths up to 70m, a 600kHz ADCP is quite adequate. In the case of depths up to 110m, the 300kHz ADCP would be more suitable. For deeper waters that might be found near Sittwe, areas with a depth of more than 1000m, it is recommended to use a 75kHz ADCP.

There are well - known ADCP current meter brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth considering. It is made of all - titanium alloy material and offers an excellent 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.