How Can We Measure the Coastal Currents of Pagadian?

1. Where is Pagadian?

Pagadian is an enchanting city in the Philippines, which is on the southwestern coast of Mindanao. The place is well blended with natural splendor and the richness of human culture.

Geographically, Pagadian lies between the blue waters of the Celebes Sea and the green expanses of Mindanao. The city is surrounded by rolling hills and mountains, which add to its scenic beauty. Pagadian Bay, lying contiguous to it, is a major body of water serving as a very important avenue in the local ecosystem and economy.

Pagadian Bay boasts clear waters teeming with marine life. To the fishermen, it is a haven because they are able to depend on the rich resources it gives them. Its coastline consists of sandy beaches and rocky shores, each with its different appeal.

Pagadian, as far as the human element goes, is a very busy urban center. Warmth in people here is as supreme as their community bonding. Starting from fresh produce to handicrafts, people are found selling everything in the vibrant markets. Cultural festivals related to heritage are pretty common and come with music, dance, and colorful parades.

2. What is the condition of the coastal currents off Pagadian?

These coastal currents near Pagadian are influenced by many factors, with tides being one of the major determinants. The tide causes a very visible deviation in the direction of flow and speed. At high tide, the waters rush to the shore, carrying nutrition with them that will influence the distribution of marine organisms. During low tide, the waters recede, showing parts of the seabed and changing the flow pattern.

Besides this also are the powerful effects of the monsoon winds. The Philippines clearly depict the shift in the different monsoon seasons, and the winds of the seasons can easily push and divert the course of the coastal currents. For example, the southwest monsoon may push them one way, whereas the northeast monsoon can cause a reversal or modification of the normal current flow.

Another very important factor is the topography of the seabed off Pagadian. The shape and slope of the ocean bottom can accelerate, decelerate, or even change the direction of the currents. If the depth suddenly changes or if there are underwater ridges, complex patterns of currents can occur. The inflow of freshwater from nearby rivers and streams may disrupt the normal saline balance of the waters along its coasts and affect the behavior of the currents.

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

To accurately estimate the coastal currents of Pagadian, there is a need to measure their velocity and flow rate. In measuring them, there have been some drawbacks with the traditional methods. However, Acoustic Doppler Current Profiler(ADCP) is more modern and at the same time easier to measure.

3.1 How do ADCPs using the Doppler principle work?

On the principle of the Doppler principle, ADCP current meter function. They send acoustic signals into the water column. The signals reflect off the particles suspended in the water, like sediment and plankton. These particles are moving with the current of the water, so when the signal bounces back, there is a change in frequency from the one emitted. This change in frequency-the Doppler shift-is directly related to the velocity of the particles and therefore to that of the water current.

An ADCP current profiler works on the basis of sending out several beams of acoustic signals at different angles from one another and is able to measure the three-dimensional velocity of a current in water. In this way, it offers the full picture of exactly how the currents are flowing not only horizontally but also vertically within the column of water. Once the data are acquired, it can then be processed to solve for the flow rate of the coastal currents, which is fundamental for a wide range of purposes like marine navigation, environmental studies, and coastal engineering.

3.2 What's needed for high-quality measurement of Pagadian coastal currents?

A number of equipment requirements are needed for high-quality measurement of coastal currents around Pagadian. First, the material reliability of the ADCP itself must be resilient to the harsh marine environment, from exposure to saltwater to high pressures at great depth, or even impacts from floating debris.

Other important variables are its size and weight, along with the ADCP flow meter power consumption. Smaller sizes and lighter weights mean that deployment and handling will be easier; in particular, if the instrument needs to be installed on different platforms such as boats or buoys. Low power consumption is needed for long-term measurements in order to keep the device working without needing to change batteries very frequently, with the added positive effect of not needing a large power source.

Another important factor is cost: the ADCP meter has to be reasonably priced so that it can be used everywhere and measurements can be done on a large scale. Of the many materials that fit most of these requirements, one is titanium alloy. Titanium alloy resists corrosion very well; hence, it would work well in the marine environment because saltwater would degrade other metals rather fast. It is also strong and durable with all sorts of pressures and stresses that come along with an underwater operation. Its relatively low density compared with some other metals means it can help keep the overall weight of the ADCP profiler low, which can be an advantage in terms of ease of deployment.

3.3 Selection of appropriate equipment for current measurement?

Different aspects are considered in choosing the appropriate equipment to measure the coastal currents of Pagadian. Firstly, the mode of deployment is dependent on the application. Some common modes of ADCPs include:

Shipborne ADCP: An ADCP fixed on a ship. It could be used in cases when a ship can move around the coastline, carrying out a survey at different sites. Shipborne ADCPs are very useful for the purpose of getting an overview of the currents along coasts over a larger area. Bottom-mounted ADCP, also sometimes referred to as sit-on-bottom ADCP: This is laid on the seabed. It would provide continuous measurement of currents passing over it. Bottom-mounted ADCPs are ideal for monitoring specific locations where a more detailed and long-term understanding of the currents is needed, like near a particular coastal structure or in an area of interest for marine ecological studies.

Buoy-mounted ADCP: ADCPs mounted on a buoy have the capacity to float freely in the water and conduct measurements of the currents surrounding it. Buoy-mounted ADCPs offer some advantages over access by ship, where such access is difficult or continuous monitoring is needed at a fixed position in the water, such as in open waters near Pagadian.

Except for the mode of deployment, one should choose an ADCP concerning frequency. The frequencies are suitable for different water depths. For instance,

A 600 kHz ADCP is suitable for shallow waters with no depths exceeding 70 meters. This frequency provides good resolution for shallower waters, allowing more detailed measurements of the currents within this depth range. A 300 kHz ADCP will have a suitable water depth of up to 110 meters. This represents a good balance between resolution and penetration depth, which probably makes it the favorite for many applications when coastal currents are to be measured within this depth range. A 75 kHz ADCP is designed for water depths up to 1000 meters. This lower frequency can penetrate deeper into the water column, hence enabling measurements in much deeper waters that could be relevant for understanding the overall structure of the coastal currents around Pagadian, extending to greater depth.

There are a few popular brands of ADCPs available on the market, including Teledyne RDI, Nortek, and Sontek. However, for those who wish to have an economic option with good quality, it would be the China Sonar PandaADCP. All-titanium alloy material will ensure that it is durable and resistant in the marine environment and give an incredible cost-to-performance ratio. Check on their website for more details of this product at https://china-sonar.com/.

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