How can we measure the coastal currents of Mindoro?

1. Where is Mindoro?

Mindoro is the seventh - largest island in the Philippines. It is located in the South China Sea and is separated from Luzon by the Verde Island Passage.

Geographically, Mindoro is a variously rugged island, with interior mountain ranges like the Mindoro Cordillera, while the peripheral areas are covered by coastal plains. It has an irregular coastline with sandy beaches and rocky shores surrounding the island, including coves and bays. Adjacent waters form part of a rich marine ecosystem, with coral reefs and seagrass beds supporting a wide variety of marine life. Colorful fish, turtles, and even dugongs abound in these waters.

The biggest human activity is fishing, relying on the rich marine resources in the surrounding seas. The tourism industry in the area is a growing one as the beaches and other natural attractions on the island draw visitors. The interior houses indigenous communities with their diverse cultures and traditions.

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

Many variables are shown to influence the coastal currents near Mindoro. One of the major influences on tidal currents is because of the gravitational pull by the moon and sun on tides. This creates ebbs and flows within the tidal currents. Because of the lunar cycle, the tidal currents can vary in strength and direction with the specific local topography along the coast as well as at the bottom of the sea.

Of no less significance are the monsoon winds. In the Philippines, there are two seasons: the southwest and the northeast monsoon periods. In the southwest or Habagat monsoon, winds generally blow from the southwest and push the surface waters, creating currents that flow in a general direction. On the contrary, during the northeast or Amihan monsoon, wind from the northeast creates different flow patterns.

Currents are further influenced by the topography of the seabed off the Mindoro coast. Submarine ridges, canyons, and shoals make the currents speed up, slow down, or shift directions. The irregular shape of the coastline-that is, its bays, headlands, and islands-further disrupts the flow in a way that causes it to split or swirl.

Freshwater inflow from rivers and streams into Mindoro can also affect the density of the coastal waters and, in turn, influence the current patterns. Warmer water near the surface may be inclined to rise and be replaced by cooler water from deeper layers, thus creating a vertical circulation which may influence the overall flow of the coastal currents.

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

The different coastal currents of Mindoro have distinctive features on velocity and flow rate. Its velocity could be from relatively slow in any sheltered bay and lagoons to quite fast where its constricted regions and/or under stronger winds or tides. The flow rate is set by the volume of water that passes through a given area per unit time.

The methods applied in the measurement of such coastal currents need to be very advanced and convenient for accurate measurement. One of the methods which have proved to be very effective includes the use of Acoustic Doppler Current Profilers. It can give flow details of water at depth continuously with great detail.

3.1 How does an ADCP work employing a Doppler principle?

The Acoustic Doppler Current Profiler(ADCP) work based on the Doppler principle. They emit acoustic signals into the water. If these acoustic waves encounter moving particles in the water, such as sediment grains or small organisms, the frequency of the reflected waves changes. This change in frequency is proportional to the velocity of the moving particles and therefore, by extension, to the velocity of the water itself.

Thus, ADCP current meter is able to measure the three-dimensional velocity of the water by transmitting several acoustic beams with different angles. Their ability includes the determination not only of the horizontal components of the velocity but also of vertical components for a full representation of the structure of the current flow. The data is further processed and analyzed to give accurate information about the coastal currents.

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

For high - quality measurements of the coastal currents near Mindoro, there are several factors concerning the equipment that should be taken into consideration. First of all, material reliability of the equipment is important. The device should be able to resist hard conditions of the marine environment: saltwater, high humidity, and different pressures.

Of equal importance are the size, weight, and power consumption of the equipment. Smaller size and lighter weight make deployment and handling easier, especially in situations where the measurement has to be made from a small boat or floating platform. Low power consumption means that equipment will be able to operate for a considerable amount of time with no need to frequently replace batteries or input an external power source.

Another important aspect is cost. In order to make large-scale measurements possible, the equipment should not be too expensive. About the casing of ADCP current profiler, it is highly suitable to use titanium alloy. There are several advantages offered by titanium alloy. It is super strong and durable material; it can stand the dissolving effect of saltwater. It also has relatively low density, which would help in keeping the overall weight of the device down. Besides, it has superior thermal properties that could be useful sometimes in extreme temperature conditions of the marine environment.

3.3 How to Choose the right equipment for current measurement?

In choosing appropriate equipment to measure Mindoro's coastal currents, a number of factors have to be considered. First is the mode of deployment. There are several types of ADCP doppler depending on the mode of deployment.

The latter applies to measurements from a ship, for which it is suitable to use a ship-borne ADCP flow meter. The ADCP may be installed on the hull of the ship and continuously take measurements as the ship moves through the water.

If the measurement is to be done from the seabed, then a bottom-mounted ADCP can be used. This kind of ADCP meter is placed at the seabed and measures the currents passing above it.

An ADCP mounted on a buoy should be used for all applications where a floating platform is used. It is also capable of attachment to a buoy whereby it measures the currents in the surrounding water.

Apart from mode of deployment, the frequency of the ADCP has to be chosen depending on the water depth. Depths up to 70 meters often find a very good choice in the 600 kHz ADCP, which gives measurements at high resolution. A 300 kHz ADCP is quite appropriate for channels that run from 70 to 110 meters in depth. A 75 kHz. ADCP will work best for deeper waters, say up to 1000 meters, because it goes deeper into the water, measuring currents accurately.

Some of the big names in the ADCP profiler market include Teledyne RDI, Nortek, and Sontek, among others. However, to have a cost-effective option with great quality, one may want to try the China Sonar ​PandaADCP. It is made from all-titanium alloy material to ensure it will live long and be reliable in the marine environment. Besides, the performance-to-cost ratio is incredible. You can have more information concerning it on its official website: ​https://china-sonar.com/.

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