How do we measure the Coastal Currents of Perak?

1. Where is Perak?

Perak is a state in Malaysia and is located along the west coast of the Malay Peninsula. To the west, it faces the Strait of Malacca-a strategic and busy water passage. The state is well-recognized for its history, tin mining heritage, and different landscapes.

The capital, Ipoh, prides itself on colonial architecture, delectable local food, and a culturally alive atmosphere. The population of Perak consists of Malays, Chinese, and Indians-each with its very own special touch to the state's cultural variety.

The Strait of Malacca to the west is a very important seaway passage that connects the Indian Ocean and the South China Sea. The Perak coastline comprises a few habitat types, including sandy beaches, mangrove forests, and estuaries. Mangroves are among the most important contributors to the ecosystem at the coastline. They protect against erosion naturally, serve as breeding areas for numerous fish, crab, and bird species, and play a crucial role in nutrient cycling. Everything from tiny planktons to large fish species, even to sea turtles, can be found in the waters of the strait.

2. What is the condition of the coastal currents near Perak?

The coastal currents around Perak are formed in a very complicated way and generally have many different controlling factors. Tidal currents are one of the major contributing factors. The gravitational attraction of the moon and the sun on the water bodies in the Strait of Malacca provides semi-diurnal tides-that is, two high tides and two low tides in a day. The tidal-generated currents can be very strong, especially at the narrow parts of the strait and near the coast.

Monsoon winds, too, play an important role. The southwest monsoon between May and September brings in strong winds that can drive the surface currents in a particular direction. During the northeast monsoon from November to March, the wind direction changes and so does the direction and speed of the coastal currents. This interaction between the monsoon - driven and tidal currents results in a complex flow regime.

This flow of coastal currents can also be deflected and modified by the local bathymetry, such as seamounts, ridges, and channels. The river and estuarine discharges into the strait will also influence the currents. Density differences caused by freshwater input from those sources may give rise to a complex current pattern.

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

Various methods are involved in viewing the coastal water flow of Perak. The surface drifting buoy method, relatively simple and practical in nature, would involve releasing buoys into the water. These buoys are fitted with GPS or other tracking devices. As the buoys get carried away by the currents, the movement over time in the said buoys in relation to the shore will help identify the direction and speed of the surface currents.

In the anchored ship technique, a ship is anchored at a position, and current-measuring instruments are used to measure the flow of water at various depths. However, it suffers from some drawbacks, such as the influence of waves and winds on the ship, which might result in incorrect measures. It is also pretty inefficient for covering a large area.

Therefore, the ADCP method is very sophisticated and effective for measuring the flow of water at the coastal area. ADCPs basically work on measuring the speed profile of currents of water over a large depth range. They do that by sending out ultrasound waves through water and analyzing the Doppler shift from the reflected waves. This allows a remarkably thorough view of the current structure all the way from the surface down to the seabed.

4. How do ADCPs applying the Doppler principle work?

Acoustic Doppler Current Profiler (ADCP) work on the basis of the Doppler principle. They send out acoustic pulses-just sound waves-into the water. These sound waves scatter off particles in the water, such as sediment and plankton or just smaller particles in general. As the wave bounces off these particles and is reflected back to the ADCP, the frequency of the reflected waves has altered because of the Doppler effect.

If the particles are moving toward the ADCP profiler, then the frequency of the reflected wave is higher than the original frequency emitted. On the other hand, when the particles are moving away from the ADCP meter, then the frequency of the reflected wave is lower. The ADCP flow meter is able to measure this frequency shift precisely and hence can find the velocity of the particles. The particles in effect move by the action of water current, and thus the velocity of these particles as calculated reflects the velocity of water current.

They can emit sound pulses in several directions, thereby enabling them to measure the velocity of the current in three-dimensional space and at different depths. For example, they can take a vertical profile and measure current velocities at depth intervals from the surface down to the seabed for a full representation of the current structure.

5. What is needed in measuring Perak coastal currents to acquire high-quality data?

For high-quality measurement of the coastal currents in Perak, the equipment should be manufactured with reliable materials. Considering how harsh the marine environment is due to saltwater corrosion and possibly physical impacts from waves and debris, the casing must be highly durable.

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 desirable to facilitate handling and installation.

Low power consumption is important for long - term measurements. Besides, cost-effectiveness allows one to perform measurements on a large scale. The casing in this case is preferably of titanium alloy for an ADCP. Titanium alloy resists corrosion excellently, which is an important fact in the marine environment of Perak. It can resist the corrosive effects which emanate from saltwater over a long period. It is strong, with a high strength-to-weight ratio, hence promising a durable yet lightweight structure which can protect the internal components of the ADCP current profiler.

6. Selection of right equipment for current measurement?

On this issue, during the selection of the right equipment in current measurement at Perak, usage is the first consideration. Ship-borne ADCP can be used for measurements from a moving vessel. Real - time current data is provided while the ship is in motion.

Bottom-mounted ADCP is good for measurements at fixed locations near the seabed; the current at a given point can be continuously monitored. When the measurements must cover over a considerable area, without restrictions to a specific depth, a buoy-type ADCP is appropriate.

Frequency Choice: In terms of the choice of frequency, a 600kHz ADCP may be useful for water depths up to 70m; a 300kHz ADCP may be appropriate for water depths of between 70m and 110m. In very deep waters of up to 1000m, a 75kHz ADCP is suitable.

There are well - known ADCP 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.