How to measure the coastal currents of Dumaguete?

1. Where is Dumaguete?

Dumaguete is a city in the Philippines. It is situated on the island of Negros Oriental, facing the Bohol Sea.

Geographically, it lies along a magnificent shoreline. The city had acquired its reputation for having a quite long shoreline, boasting fine sandy beaches and clear blue waters. The nearby Bohol Sea forms part of a marine biologically diverse area. Within the area are coral reefs serving as a habitat to a variety of marine organisms comprising ornamental fish, sea turtles, and many invertebrates. Along the shores are some rocky outcrops showing gentle slopes up to the sea.

Dumaguete is popular for tourist travel. There are beaches, diving, snorkeling, and further water-based activities that people enjoy. Fishermen fish off the coasts of Dumaguete. The local industry thrives from the rich marine resources. Other important aspects of the city include higher education through universities and a strong cultural base pertaining to history. Moreover,

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

Several influences act upon the coastal currents near Dumaguete. At the center of all other influences is the tidal current force. The tides rise and fall according to the gravitational pull of the moon and the sun, resulting in tidal currents. Their strength and direction can vary with the lunar cycle and with local topography of coastline and seabed.

The monsoon winds, on the other hand, play an important role. There are two seasons of monsoon over the Philippines. In the southwest monsoon (Habagat), the wind blows from the southwest with a tendency to push the surface waters, thereby developing currents that generally flow in a common direction. In contrast, during the northeast monsoon, the winds from the northeast result in different flow patterns.

Topography around Dumaguete influences the current along its coasts. Such underwater ridges, shoals, and channels can accelerate, decelerate, or even deflect currents. The shape of the coastline with bays and headlands influences the flow of the currents, too. Inflow of fresh water from local rivers may affect the density of coastal waters and influence current patterns.

3. How to observe the Dumaguete's Coastal water flow?

Characteristics of coastal currents at Dumaguete show variation in velocity and flow rate. Velocity can vary from a relatively slow pace in the sheltered bays and lagoons to a remarkably fast rate of speed through areas where constricting topography funnels the flow or where stronger winds or tides impinge. The flow rate refers to the volume of water that is transported through a given area per unit time.

For the correct measurement of these coastal currents, advanced and easy methods are essential. One of the effective methods used for this very purpose is the employment of Acoustic Doppler Current Profiler(ADCP) is effective in offering variable-depth continuous water flow information with high resolution.

3.1 How do Doppler principle ADCPs work?

The ADCP current meter operate based on the principle of the Doppler effect. They send acoustic signals into the water. When these acoustic waves encounter moving particles in the water, like 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, in turn, to the velocity of the water itself.

Because ADCP current profiler send out several acoustic beams, falling at different angles, they are able to take three-dimensional velocity measurements of the water. To say it in other words, they can determine the horizontal velocity and even the vertical components of the current velocity, which would give a comprehensive understanding of the structure of the flow of water. Data downloaded are processed and analyzed afterwards to deliver results representing accurate information about currents along the coasts.

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

Many are the factors to be considered for high-quality measurement of the coastal currents around Dumaguete when it comes to equipment. First, material reliability of the equipment outlives the harsh marine environment because of saltwater, high humidity, and varying pressures.

Notably, the size and weight of the equipment are critical, besides the power consumption. Smaller in size and lighter in weight, it is easier to deploy and handle, especially in those situations where the measurement has to be done using a small boat or floating platform. Low power consumption to ensure that the equipment can operate for a longer period without needing to replace the batteries frequently or find sources of external power.

Cost is another important factor. For enabling large -scale measurements, the equipment must be reasonably affordable. One of the most appropriate materials for ADCP flow meter casing is titanium alloy. It has a number of advantages. Firstly, it is very strong and resilient and can resist the degrading action of seawater. It also has a relatively low density, which helps in keeping the overall weight of the device down. Additionally, it has great thermal properties that perhaps may assist during the time of working in a marine environment that may be very extreme in temperature.

3.3 How to Choose the Appropriate Equipment for Current Measurement?

The selection of appropriate equipment to measure the currents in the coast of Dumaguete should consider several aspects, such as the mode of deployment. There is an existence of different types of ADCP meter serving their purpose in terms of the way they are deployed.

An ADCP borne by a ship is quite suitable for such measurements, as it can be mounted on the hull of the ship and give continuous measurement while the ship moves along in the water.

If the measurement is to be done from the seabed, a bottom-mounted ADCP can be put to use. Such an ADCP profiler is placed on the seabed and measures the currents passing above it.

Where an application utilizes a floating platform, an ADCP mounted on a buoy is the way to go. It can be attached to a buoy and measure currents in the surrounding water.

Besides the mode of deployment, the frequency of the ADCP also needs to be selected based on the depth of the water. At water depths as many as 70 meters, a 600 kHz ADCP can normally be decent due to its high-resolution measurement. For waters running deeper than that, specifically between 70 and 110 meters, an ADCP of 300 kHz is more appropriate. An ADCP of 75 kHz for much deeper waters, say up to 1000 meters, is recommended; it can delve further into the water to measure the currents accurately.

Among the prominent brands, one could name Teledyne RDI, Nortek, and Sontek. However, there is a cost-effective excellent quality ADCP for those in need; one could refer to the China Sonar PandaADCP. Material: All-titanium alloy in manufacture ensures strength and reliability within the marine environment to achieve an incredible cost-performance ratio. You can learn more at their website: https://china-sonar.com/.

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