How to Measure the Coastal Currents of Myeik?

1. Where is Myeik?

Myeik is a city in Myanmar and is located in the Tanintharyi Region. This is indeed a coastal jewel, with a peculiar geographical position: the city nestled along the Andaman Sea, a body of water known for its warm waters and rich biodiversity.

Myeik hosts a lively and diverse population. The local people are attached to the sea, and their culture is tinged with the various maritime activities that have been a part of their lives. Architecture in the city represents both the traditional and modern blended style. The coastline around Myeik is made up of long expanses of sandy beaches that are joined together by rocky outcrops and small coves. The Andaman Sea, which lies alongside the Andamans, is home to a rich fauna of marine life, including brightly colored coral reefs and innumerable fish species. It constitutes a considerable source of income from fishing and the cultivation of pearls.

The surrounding waters are dotted with numerous islands that form an archipelago. These islands further beautify the area and play a significant role in the local ecosystem. The mangrove forests along the coast protect shorelines and serve as a nursery for many marine organisms.

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

Various factors account for the conditions of the coastal currents off Myeik. The dominating force comes from the winds of the monsoon. During the southwest monsoon, the strong winds can drive the surface currents through the water, often controlling the direction and speed of the flow. Tidal forces also play an important role. Because of the rise and fall of the tides, the speed and direction of the currents change.

The relief of the bottom and the shape of the shore are of crucial importance. Submarine ridges, channels, and shoals can cause deflection, convergence, or eddying of currents. The differences in water temperature between the open sea and the near-shore contribute to the formation of density currents. The inflow of fresh water from rivers and estuaries in the area can also affect the salinity and density of the coastal waters, hence affecting the current pattern.

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

Surface Drifting Buoy Method: This is a relatively simple approach whereby a buoy is let into the water and its travel through time is traced. The position of the buoy gives information about the direction and speed of the surface current. However, this method does have its drawback. It measures the surface current, and there is interference with wind and waves. For instance, if the wind is strong, then that would make the buoy's movement not representative because it gets pushed off-course.

Anchor - Boat Method: In this method, a boat is anchored at a specific location, and the current meters are deployed from the boat. This allows for measurements at different depths. But this has also its own drawbacks. Since the boat position is fixed, it can sample only a small area and may not give the entire variability of currents in the major coastal region.

ADCP is a more advanced and convenient method for measuring coastal currents. It can measure the water velocity at several depths simultaneously. The device emits acoustic signals and then detects the Doppler shift of the reflected signals to calculate the water velocity. Due to the fact that the operation is not heavily influenced by surface disturbances, the ability to function continuously over an extended time creates a better understanding of the current structure.

4. How do ADCPs using the Doppler principle work?

ADPs work on the principle of the Doppler effect. They transmit acoustic pulses into the water. When these pulses find moving water particles, due to the Doppler effect, the frequency of the reflected pulses changes. If moving water particles are moving towards the ADCP, then the reflected signal frequency is higher than the emitted one; if they are moving away, it would be lower.

The ADCP has several transducers that send and receive signals at different angles. By measuring the Doppler shift from various directions and at different depths, it can work out the velocity of the water in three-dimensional space. It may calculate, for instance, the horizontal and vertical components of the velocity thus giving a detailed profile of the current from the surface to the seabed.

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

The equipment to measure the coastal currents in Myeik should have specific characteristics for high-quality results. First, materials used for that equipment should be reliable enough to maintain strength for a long time in the corrosive marine environment. There should be compact sizing in the device to enable easy deployment and retrieval, especially for such areas with complex coasts like Myeik.

It would be better if the design were lightweight for easier handling during installation and maintenance. Low power consumption is essential to support long-term operation, particularly if the equipment is to be deployed to remote locations. Cost-effectiveness is also important to enable large-scale measurement.

The casing of ADCPs is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance, which is vital for withstanding the corrosive seawater. It is also strong and durable, capable of withstanding the pressure of the water at different depths. Its lightweight nature is an added advantage for ease of use.

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

Equipment selection for measuring current in Myeik will have to consider the following factors. First is the purpose of use. When the measurement is for a vessel's navigation, a ship-mounted ADCP is sufficient. It can provide real-time current information throughout the voyage.

For near-bed measurement, a bottom-mounted ADCP will be a better choice to capture the near-bottom current characteristic. In addition, if a large area is to be continuously monitored for a longer period, the buoy-type ADCP would be appropriate.

Frequency of ADCPs: Different frequencies suit different water depths. The 600kHz ADCP shall be good to go for water depths up to 70m, while the depth up to 110m requires a 300kHz ADCP. For more profound waters, like the ones in some areas around Myeik, it requires over 1000m to go with 75kHz.

There are well - known ADCP brands like Teledyne RDI, Nortek, and Sontek. Additionally, a Chinese brand, China Sonar PandaADCP, is 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.