How can we measure the coastal currents of Pattaya?

1. Where is Pattaya?

Pattaya is a city located in the Chon Buri province of Thailand, on the eastern coast of the Gulf of Thailand. It is one of the most well - known tourist destinations in Southeast Asia.

It is famous for beaches, stretching along the whole coastline of the city. Among the most popular are Pattaya Beach and Jomtien Beach, boasting tender sand and transparent blue-green water. In the vicinity, there is a recreational center, restaurants, bars, nightclubs, and centers of water sports are represented in great numbers. The vivid nightlife and a great variety of tourist attractions bring visitors to Pattaya from all over the world.

Tourism plays a very significant role in the local economy, but fishing also has its place. The population of this city consists of a mixture of Thai locals and a high number of expatriates and migrant workers. The cultural landscape is traditional with Thai values intertwined with modern, international influences courtesy of the influx of tourists.

The Gulf of Thailand, which lies adjacent, is a more or less shallow body of water teeming with life, one will find a great variety of fish, shellfish, and coral reefs in their midst. The sea constitutes an important constituent of the local ecosystem and a natural playground for water-based sports, diving, snorkeling, and jet-skiing.

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

The coastal currents near Pattaya result from a combination of the contributing factors. Tidal currents are the dominant forces. The tides in the Gulf of Thailand are semi - diurnal due to the moon and sun gravitational pull, meaning there are two high tides and two low tides every day. Tidal currents are very strong, particularly near the coast and in places where the water is constrained, like near river mouths or around piers. These are very important in sediment and nutrient transport, which are vital for coral reefs and the general health of the marine ecosystem.

Monsoonal winds also have a profound effect. The southwest monsoon, from May to September, provides strong winds that can drive the surface currents in one direction. The northeast monsoon, from November to February, completely reverses the wind direction and therefore the direction and speed of the coastal currents. Interaction between tidal and monsoon-driven currents generates a complicated and dynamic pattern of flow.

The local bathymetry, including the shape of the seabed and the presence of underwater features such as ridges and channels, can redirect and modify the flow of the coastal currents. The discharge of local rivers and streams into the sea can also affect the current patterns. The freshwater input from these sources can create density differences that lead to the formation of complex current systems.

3. How to Observe Coastal Water Flow of Pattaya?

There are a few methods to observe the coastal water flow in Pattaya.

The Surface Drifting Buoy Method

This is quite simple and practical. Buoys are put in the water, so they will carry GPS or any kind of tracking devices. Since buoys move with the currents, it is possible to follow their position in space and time and get a real idea about the direction and speed of the surface currents. The buoys would have to be designed to take local marine conditions, like the wave climate and the corroding capacity of saltwater, into consideration.

The Anchored Ship Method A ship is anchored at a particular place, and current-measuring instruments are suspended from the ship. The instruments can record the speed as well as direction of the movement of water in the flow at various depths. This approach, however has considerable drawbacks. The ship itself may be influenced by the waves and wind, and thereby yield incorrect measures of the currents. The efficiency regarding large area coverage is also not satisfactory.

The Acoustic Doppler Current Profiler (ADCP) Method This is a more advanced and efficient method of measurement of the flow of water along coasts. The acoustic Doppler current profiler can give the velocity profile of water currents over quite a big depth range. It basically works by transmitting sound waves into the water and analyzing the frequency shift in the reflected sound waves due to Doppler shift. This yields a pretty good understanding of the structure of the current from surface to seabed.

4. How do ADCPs using the Doppler principle work?

The basic operation of ADCPs is based on the principle of the Doppler effect: ADCPs emit acoustic pulses, or sound waves, into the water. Particles in the water-sediment, plankton, and other small particles-serve as reflectors for these sound waves. If those sound waves bounce off the moving particles and are reflected back to the ADCP current meter, their frequency changes due to the Doppler effect.

The reflected wave frequency is higher than the original emitted frequency if the particles are moving towards the ADCP current profiler. On the other hand, if they are moving away from the ADCP, the reflected wave frequency will be lower. The ADCP can calculate the velocity of the particles by precisely measuring this frequency shift. Because the particles are in motion due to the water current, the velocity of the particles calculated will measure the water current velocity.

They can radiate sound pulses in many different directions. They can measure three - dimensional current velocities at different depths. For instance, on a vertical profile, they can measure the current velocity at some intervals from the surface down to the seabed, giving a detailed view of the current structure.

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

The equipment should be made of reliable materials that can provide high-quality measurement of the currents in Pattaya. Considering the harsh marine environment with saltwater corrosion and probable physical impacts due to waves and debris, the casing should be durable.

The size of the equipment should be small enough to be easily deployed, especially in areas with limited access, like in small boats or in shallow coastal waters. The design should also be lightweight for more convenient handling and installation.

Long-term measurements require low power consumption. Cost-effectiveness is another critical parameter that permits large-scale measurements. For this matter, the casing is preferably made from titanium alloy for ADCPs. Titanium alloy will provide very excellent corrosion resistance, which is so cardinal in the marine environment of Pattaya. It can sustain the corrosive salinity in water for a long period. Besides, it is strong enough and has a high strength-to-weight ratio to give a lightweight yet durable structure that would protect the internal components of the ADCP flow meter.

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

The usage is the first consideration when choosing the right equipment in measuring the current in Pattaya.

For Measurements from a Moving Vessel

A ship - borne ADCP meter is suitable. It can provide real - time current data while the ship is in motion, allowing for a better understanding of the water flow in different locations.

For Measurements at a Fixed Location near the Seabed A bottom-mounted ADCP flow meter would be an excellent choice. It can monitor the current at a single point continuously for consistent data in the time series.

For Measurements that Need to Cover a Wide Area and Are Not Restricted to a Specific Depth

A buoy-type ADCP current profiler is suitable. It can cover a more significant area and is not restricted by any depth constraint.

For water depths from 70m or less, an ADCP of 600kHz is a reasonable choice. For further depth ranges between 70m up to 110m, it is better to opt for the 300kHz ADCP. For a very deepwater of up to 1000m, a 75kHz model ADCP would be preferable.

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 a great cost - performance ratio. You can find more information about it on the website: https://china-sonar.com/.

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