How can we measure the coastal currents of Masbate Island?

1. Where is Masbate Island?

Masbate Island is in the central Philippines. It belongs to the Bicol Region and is bounded by the Burias Pass to its north, the Ticao Pass to its south, and the Sibuyan Sea to its west.

Geographically, it has a diverse landscape. It has rolling hills and plains, with a coastline of mixed sandy beaches, rocky shores, and mangrove forests. The adjacent waters comprise an important part of the vibrant marine ecosystem. The seas around Masbate are inhabited by marine life, including several species of fish, crustaceans, and mollusks. Some areas also contain coral reefs, which, aside from being a home to a diverse array of organisms, also act as a natural barrier that helps in the protection of the coast from erosion.

Fishing has been the leading industry in the area as far as human activities are concerned. The fishermen in this locality depend for their livelihood on the richness of the marine resources in the surrounding waters. Masbate is also known for raising cattle, with the plains of this island offering suitable grazing lands. In this area, tourism is also developing because many visitors are attracted by the lovely beaches and peculiar coastal scenery.

2. What is the condition of the coastal currents off Masbate Island?

Several factors interact to influence the coastal currents in the vicinity of Masbate Island. One major factor is the tidal currents, which are brought about by the gravitational pull of the moon and the sun on raising and lowering the tides and thus creating currents. In this regard, tidal currents can be variable in relation to the lunar cycle and also the local topography of coastline and seabed.

The monsoon winds also take part in this matter. There are two monsoon seasons in the Philippines: during the southwest monsoon, or Habagat, winds blow from the southwest and push the surface waters to create currents that flow generally in a particular direction, and during the northeast monsoon, or Amihan, where the wind from the northeast creates different flow patterns.

The underwater topography around Masbate Island contributes to the variations of coastal currents, which could include an underwater ridge, shoal, and channel, which can accelerate, decelerate, and even alter the direction of these currents. The shapes of the coastline, like bays, headlands, and estuaries, may also provide additional influence on the flow in the current. Inflow of freshwater from rivers and streams within the locality may influence the density of the waters along the coast and alter the pattern of the currents.

3. How to Observe the Flow of Water in the Coast of Masbate Island?

Coastal currents around Masbate Island have definite characteristics regarding their velocity and flow rate. Velocity may be relatively slow in sheltered bays and lagoons but quite fast in regions where the current is constricted or where stronger winds or tides may be prevailing. The flow rate would be dependent on the amount of water passing through a given area per unit time.

To measure such coastal currents, much-advanced and easy techniques are indispensable. Among these techniques, one can name the ADCP current profiler that have emerged as highly effective to generate relevant data. ADCP current meter can give detailed and continuous information related to the flow of water at varied depths.

3.1 Principles of operation of Doppler-based ADCPs

As the Acoustic Doppler Current Profiler(ADCP) name suggests, these instruments work on the principle of frequency shift outlined by the Doppler principle. They send acoustic signals out into the water. When those acoustic waves come into contact with particles in the water that are in motionsediment grains or small organisms, for examplethe frequency of the reflected waves changes. This change is proportional to the velocity of the moving particles and, by extension, the velocity of the water itself.

Because they are able to send out multiple acoustic beams at various angles, ADCP doppler is able to measure the velocity of the water in three dimensions. They can calculate not just the horizontal velocities but even the vertical velocity components, which are necessary for complete understanding of the water flow structure. After the data is acquired, it is processed and analyzed for more accurate information on the coastal currents.

3.2 What is required to provide a high - quality measurement of the coastal currents around Masbate Island?

The following are some equipment-related variables that need consideration in the high-quality measurement of the coastal currents near Masbate Island. First and foremost, reliability of material used in the equipment. The device ought to be resistant to the harsh conditions of the marine environment to which it will be exposed, such as saltwater, high humidity, and changes in pressure.

by size, by equipment weight, and by power consumption. A lighter, smaller-sized equipment is easier to deploy and handle, particularly in situations where measurements have to be done from a small boat or from a floating platform. In many instances, power consumption must also be low in order to let the equipment operate for long time without frequent battery replacement or external power sources.

Another very important factor is cost. In order for large-scale measurements to be possible, the equipment should be relatively inexpensive. Among materials highly suitable for the casing of ADCP flow meter , there is a titanium alloy. There are several advantages to using a titanium alloy. It is very strong and resilient, and it may resist the corrosive action of saltwater for a long time. Its density is also relatively low, which is good because it keeps the general weight of the device low. Finally, it has great thermal properties and hence may be useful in extreme temperature conditions that may occur within the marine environment.

3.3 How to Choose the right equipment for current measurement?

The correct type of equipment that needs to be used in measuring the coastal currents in Masbate Island requires consideration of several factors. First to be considered is the mode of deployment, wherein there are various types of ADCP meter depending on the mode of deployment.

A proper measurement from a ship can be done with a ship-borne ADCP profiler. It can be mounted on the hull of the ship and make continuous measurements when the ship is in motion through the water.

If the measurement has to be done from the seabed, a bottom-mounted ADCP can be used. This sits on the seafloor and measures the currents passing over its head.

An ADCP mounted on a buoy would be the solution for all those applications where there is usage of a floating platform. The instrument can be attached to a buoy and measure currents in the water surrounding it.

Apart from the mode of deployment, the frequency of the ADCP also has to be selected with regards to water depth. A 600 kHz ADCP is usually a good choice for water depths up to 70 meters because high-resolution measurements are achieved. For depths between 70 and 110 meters, a 300 kHz ADCP would be more appropriate. In the case of deeper waters, such as those up to 1000 meters, a 75 kHz ADCP should be used since it has greater depth penetration and can measure the currents more accurately.

The well-known brands available in the ADCP market are Teledyne RDI, Nortek, and Sontek. However, for those who want economical pricing with excellent quality, one should consider the China Sonar PandaADCP. The material of the all-titanium alloy has ensured its durability and reliability in the marine environment. Apart from that, it guarantees an extraordinary cost-performance ratio. You can check for more information on the official website: https://china-sonar.com/.

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