How can we measure the coastal currents of Chon Buri?

1. Where is Chon Buri?

Chon Buri is a bustling province in Thailand, which is located on the eastern shores of the Gulf of Thailand. It's a region that combines busy urban life with beautiful coastal scenery.

The province is well-liked for its popular tourist destinations, including that of Pattaya. Pattaya is a world-renowned beach resort city that attracts millions of visitors every year. The area features long sandy beaches, a vibrant nightlife, and an array of water sports activities. Besides tourism, the local economy draws much of its strength from fishing, manufacturing, and trade.

There are both locals from Thailand and expats in Chon Buri. The cultural scene is diversified, marked by a mixture of traditional Thai values and international themes brought about by modernization. The fishing communities in the coastal areas have a long-standing attachment with the sea.

The nearby body of water, the Gulf of Thailand, is shallow and warm. It is a haven for various types of marine life. The waters are a host to many species of fish, shellfish, and coral reefs. The coral reefs are not only a natural beauty but an important part of the marine ecosystem, serving as a home to countless organisms.

2. What is the condition of the coastal currents in Chon Buri?

The coastal currents off Chon Buri are influenced by several factors. Tidal current is one of the most dominant factors. The tides in the Gulf of Thailand are semi-diurnal, resulting from the gravitational pull of the moon and the sun. In this system, there are two high tides and two low tides each day. They are considerably strong tidal currents, particularly near the coast and areas with constricted water, like at the mouths of rivers or inlets. These are of great importance in the transportation of sediments and nutrients that are basically required by the growth and maintenance of the coastal ecosystem.

Monsoon winds also have a major impact. The southwest monsoon, which occurs from May to September, brings strong winds that can drive the surface currents in a particular direction. The northeast monsoon, from November to February, changes the wind direction and thus the direction and speed of the coastal currents. The interaction between the tidal and monsoon - driven currents creates a complex and dynamic flow pattern.

It may be deflected and changed in shape by the local bathymetry, seabed topography, and underwater features such as ridges and channels. In addition, the discharge of rivers into the sea influences current patterns. The fresh water supply from these rivers can cause density differences that may be responsible for the formation of a more complex current system.

3. How to observe the coastal water flow of Chon Buri?

There are so many ways to observe the coastal water flow in Chon Buri.

The Surface Drifting Buoy Method

This is somewhat a straightforward, practical method. Buoys are deployed in the water and fitted with GPS or other types of tracking devices. Since the buoys are transported by the currents, their position and movement over time can be observed to deduce the direction and speed of the surface currents. The buoys should be designed to resist the local marine conditions, which include the effects of waves and the corrosive nature of saltwater.

The Anchored Ship Method: A ship is taken to the desired position and anchor is dropped. Current-measuring instrument deployed from the ship. These can measure the velocity and direction of the flow of water at different depths. However, the shortcomings in this are that the ship may be subjected to waves and wind which could result in incorrect readings. Besides that, it is not very effective in covering a large area.

The Acoustic Doppler Current Profiler (ADCP) Method

This is the advanced and increased efficiency of measuring the flow of water at the coast. The ADCPs can measure the velocity profile that current water has through wide ranges in depth. This instrument sends out sound waves into the water and measures the frequency shift in the returning waves, or Doppler shift. This gives a detailed understanding of the structure of the current from the surface to the bottom.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the basis of the Doppler principle. They send acoustic pulses into the water, which involves sound waves interacting with particles in the water, such as sediment, plankton, and other small particles. When these sound waves are reflected back to the ADCP current meter due to these particles, their frequency changes due to the Doppler effect.

If the particles are moving towards the ADCP current profiler, then the frequency of the reflected wave is higher than the original emitted frequency. If the particles are moving away from the ADCP flow meter, the frequency of the reflected wave is lower. By measuring precisely this frequency shift, the ADCP is able to calculate the velocity of particles. Since these particles are moving with the flow of water, the computed velocity of the particles will relate to the velocity of water current.

While it measures for current velocity in three-dimensional space and different depths, each ADCP meter is capable of emitting sound pulses in multiple directions. For instance, in a vertical profile, they can measure the current velocity at different intervals from the surface to the seabed to give an overall picture of the current structure.

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

The equipment must be made of reliable materials for high-quality measurement of the coastal currents in Chon Buri. A durable casing is quite important because the marine environment is very harsh, with saltwater corrosion and potential physical impacts from waves and debris.

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

Low power consumption is crucial for long - term measurements. Cost - effectiveness is also important to enable large - scale measurements. In the case of ADCPs, the casing is preferably made from titanium alloy. Titanium alloy has excellent corrosion resistance, which is vital in the marine environment of Chon Buri. It is able to bear the corrosive effects of saltwater for a long period. It is also strong and has a high strength-to-weight ratio, providing a durable and lightweight structure that can protect the internal components of the ADCP profiler.

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

In choosing the right equipment in Chon Buri for making the current measurement, the usages are first of all considered.

For Measurements from a Moving Vessel

A ship-borne ADCP meter would be appropriate. It can deliver current data in real time while the ship is underway for an enhanced understanding of the flow of water at any given location.

For Measurements at a Fixed Location near the Seabed

A bottom-mounted ADCP flow meter would be one such choice. It would allow continuous observation of the current from the same point while delivering regular data for consistency over time.

For Measurements that Need to Cover a Wide Area and are not Restricted to a Specific Depth Buoy - type ADCP current profiler is appropriate as it covers a larger area and it is not restricted to a particular depth.

Coming to the frequency choice, < 70m water depth a 600kHz ADCP will be an excellent choice. For depths lying between 70 and 110m, a 300kHz ADCP is most apt. Similarly, very deep waters with depth up to 1000m require 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 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.