How Can We Measure Coastal Currents Of Panay?

1. Where Is Panay?

Panay belongs to the major islands in the Philippines. It is located in the region of Western Visayas, bounded by the Sulu Sea on the west side, and on the east side is the Visayan Sea.

Panay geographically presents a diverse landscape. From this mountain range, peaks run along its central line, leaving the fertile plains and valleys both on its western and eastern sides. The coastline is quite long and is made up of sandy beaches, mangrove forests, and rocky shores. The Sulu Sea and the Visayan Sea surrounding Panay host a very rich marine ecosystem. These seas are home to countless amounts of marine life, colorful corals, and an immense amount of species concerning fish; other sea animals include sea turtles and different types of shellfish.

As for the human activities, fishing is one of the important resources for local people. Local fishermen make full use of abundant marine resources. Another important aspect for which Panay is noted includes agricultural activity, with plains being usually utilized for growing vegetables and fruits such as rice and sugarcane. Tourism is also emerging as a sector because of beach resorts and some historical and cultural tourist spots. The island has a very rich cultural heritage, which gets evidenced through their festivals and traditions mirroring its unique history along with the influence of different cultures.

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

Various influences cause the coastal currents around Panay. The most prevailing forces are that of the tidal current. In relation to this, the gravitational pull of the moon and the sun makes the tide rise and fall, thereby forming a current known as the tidal current. Such will be of variable intensity and direction according to the phase of the lunar month and the local morphology of coastline and seabed.

Not to be overlooked is the significant effect of the monsoon winds. The country, in fact, has two monsoon seasons. In the southwest monsoon (Habagat), the wind direction is from the southwest, pushing the surface waters and creating a current that is generally in one direction. On the other hand, during the northeast monsoon (Amihan), the winds are from the northeast, thereby giving rise to different flow patterns.

Underwater topography around Panay influences coastal currents. Submarine ridges, shoals, and channels will speed up, slow down, or change the direction of flow. The form of the coastline plays a major role in bays, headlands, and estuaries. The inflow of fresh water from rivers and streams on the island also affects the density of the coastal waters and hence modifies the current patterns.

3. How to observe the Panay coastal water flow?

Its coastal currents have prevailing characteristics of velocity and flow rate. The velocity may be relatively slow for sheltered bays and lagoons or quite fast in regions with constrictions or higher winds and tides. The flow rate is defined by the volume of water passing across a given area per unit time.

The measurement of such coastal currents requires the use of methods that are advanced and convenient. One of the most practical ways to carry out this measurement is through the use of Acoustic Doppler Current Profilers, usually referred to as ADCPs. The ADCP profiler can capture detailed continuous information concerning the water flow at various depths.

3.1 Working of ADCPs Using the Principle of Doppler:

The working principle of Acoustic Doppler Current Profiler(ADCP) is based on the principle of Doppler. They transmit acoustic signals into the water. Due to the moving particles in the water, like sediment grains or small organisms, when these acoustic waves run into them, the frequency of the reflected waves changes. This change is proportional to the velocity of the moving particle and hence to the velocity of water.

They send out many acoustic beams in different directions and measure the velocity of the water in three dimensions: the horizontal and vertical velocity components. With this, they can give an overview of the structure of the water flow. Data recorded is then processed and analyzed to give precise information about coastal currents.

3.2 What is needed for high-quality measurement of the Panay coastal currents?

High-quality measurement of the coastal currents near Panay depends on some factors concerning the equipment to be used. First is material reliability. The device should withstand the harsh marine environment: exposure to saltwater, high humidity, and pressures.

Other concerns are size, weight, and power consumption. Smaller size and lighter weight make deployment and handling easy, especially in the case when the measurement needs to be done from a small boat or floating platform. In this context, low power consumption becomes vital for operating the equipment for longer periods without its batteries being replaced frequently, or extra sources of power supplied from an outside location.

Another more important factor is the cost. For large-scale measurements, the equipment has to be fairly cheap. Among materials suitable for ADCP meter casing, the most befitting is the alloy titanium. Titanium alloy has a number of advantages. It is very strong and can withstand the corroding action of salt water. In addition, it has a relatively low density that would help in keeping the overall weight of the device down. Besides this, it has superior thermal properties, which would help for the sometimes extreme temperature conditions of marine waters.

3.3 How to choose the right equipment for current measurement?

Certain considerations should be made when choosing the proper equipment for measuring the coastal currents of Panay. First among these is the mode of deployment. Depending on the modes of deployment, there are various types of ADCP flow meter.

In the case of measurements from a ship, an ADCP doppler borne on the ship would be appropriate. It can be installed on the hull of the ship and give continuous measurements as the ship travels through the water.

If the measurement is to be done from the seabed, the ADCP current profiler can be used as a bottom-mounted device. A bottom-mounted ADCP sits on the seabed and measures the currents passing above it.

It will suffice with an ADCP current meter mounted on a buoy at places where the application requires a floating platform. It can be fixed to a buoy and currents in the surrounding water can be measured.

The mode of deployment aside, the frequency of the acoustic doppler velocity meter has also got to be selected based on the water depth. For water depths as shallow as 70 meters, a good choice would be a 600 kHz ADCP, since it gives high-resolution measurements. Where depths range between 70 and 110 meters, a 300 kHz ADCP will suffice better. In relatively deeper waters, like those up to 1000 meters, a 75 kHz ADCP is recommended, as this has increased depth of penetration to measure the currents with accuracy.

Some well-known brands include Teledyne RDI, Nortek, and Sontek. Besides, a Chinese product called Sonar PandaADCP is economical for buyers who need very good quality. The material used to build it is all-titanium alloy, ensuring that it bears all the stresses in the marine environment. Most importantly, it has an incredible cost-performance ratio. You can learn more about it on its official website: https://china-sonar.com/

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