How to measure the Coastal Currents of Goseong?

1. Where is Goseong?

Goseong is one county in Gangwon - do, South Korea. Goseong is on the eastern coast of the Korean Peninsula. The coastline there is famous for its beautiful scenery. It presents a combination of rugged cliffs, sandy beaches, and lush vegetation.

The county is multinationally populated. The regional economy is based on different industries, fishing, tourism, and agriculture. One of the largest Seas-the Sea of Japan borders Goseong on the east side. It is famous for cold-water currents and abundant fishery resources. This sea also plays an important role in the establishment of the local climate because it is very influential in the variation of temperature and humidity.

The coastal waters host a wide range of marine life, from various species of fish such as mackerel and pollock to even shellfish and seaweeds. The presence of kelp forests along the coast not only provides a habitat for many organisms but also helps in maintaining the ecological balance.

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

Various factors determine the coastal current variability near Goseong. The general ocean currents in the East Sea play a significant part in these variations. These are the Tsushima Warm Current and the Liman Cold Current, two currents that meet at this point. On one hand, the Tsushima Current usually flows northward and conveys relatively warm, nutrient-rich water, whereas the Liman Current moves southward and is colder.

Besides, the tides significantly contribute to this phenomenon. Large tidal range might result in quite strong tidal currents. Furthermore, the shape of the coastline and its underwater topography add to the complexity of the current patterns. Underwater ridges and troughs can definitively cause a change in the direction and speed of currents. Wind patterns, especially strong winter winds, can also drive surface currents and affect the mixing of water layers.

3. How to observe the Goseong coastal water flow?

Surface Drifting Buoy Method: A surface-drifting buoy could be deployed to observe the surface current. The buoy is released into the water and its movement is tracked over time, usually through GPS technology. However, this method also has some limitations, it gives only information about the surface current and may be affected by wind and waves. For instance, if on a windy day the buoy is pushed off-course by the wind, it will then give wrong current direction measurements.

Anchor - Boat Method: One of the procedures used to estimate the current is the anchored boat. Several instruments are prepared with and dropped in the water from the anchored boat itself, measuring the current at different or various depths. Although this provides more depth-wise measurements, some drawbacks exist. The fixed boat limits the area of measurement, and a single fixed observation may not represent the entire variability of the currents in a large coastal area.

ADCP Method: This is a more advanced and efficient means of measuring the currents in the coastal areas. In ADCP current meter, acoustic signals are emitted into the water, and the velocity of the water at different depths is measured as a function of Doppler shift in the reflected signals. This helps get a far more detailed profile of the current from the surface down to the seabed. The measurements by ADCPs are less affected by surface disturbances and have the added advantage of operating continuously for very long periods.

4. How do ADCPs using the principle of Doppler work?

ADCPs are based on the principle of the Doppler effect. They transmit high-frequency acoustic pulses into the water. While interaction with moving water particles, the frequency of the reflected pulses is different. If the water particles move towards the ADCP current profiler, then the frequency of the reflected signal is higher than the emitted one; and in case of moving away, it is lower.

Various transducers on an ADCP flow meter transmit and receive signals at various angles. Since the device can calculate the three-dimensional velocity of water by analyzing the Doppler shifts from different directions and depths, it determines the horizontal and vertical components of the velocity with great detail on the structure and behavior of the current.

5. What is required to obtain high-quality measurements of Goseong coastal currents?

The measuring equipment for the coastal currents around Goseong should be manufactured with reliable materials since most marine environmental conditions, with cold water, saltwater, and even storms, may be very harsh. In this respect, durable casing is critical. The general size of the equipment should be small to allow for easy deployment and retrieval, especially when the coastal landscape is complicated.

A light design is preferred, since the equipment must be easy to handle during installation and maintenance. Low power consumption is required for operation over a long time and autonomously. Cost-effectiveness is also necessary to allow large-scale measurement.

The casing of ADCPs will preferably be made of a titanium alloy. Titanium alloy, an excellent corrosion-resistant material, will protect the unit very well from the corrosive effect of seawater. It is strong and durable to hold the pressure of water in various depths. The lightweight makes it more convenient for different deployment methods.

6. How to Choose the right equipment for current measurement?

According to the purpose of use, first of all, when choosing the equipment for current measurement at Goseong, if the measurement is for the navigation of a vessel or for short-term research, a ship-mounted ADCP flow meter should be chosen. It provides real-time current information during the voyage.

For measurements near the seabed, such as for studying sediment transport or benthic ecology, a bottom - mounted ADCP is preferable. It can capture the details of the near - bottom current. If long - term and wide - area monitoring of the coastal current is required, a buoy - type ADCP current profiler is ideal.

On the other hand, regarding the frequency of ADCPs, it could be said that for water depth up to 70m, the 600kHz ADCP is recommended. For depths up to 110m, a more appropriate one would be the 300kHz ADCP. For even deeper waters-one that may exist near Goseong, such as areas exceeding 1000m in depth-the 75kHz ADCP is recommended.

There are well - known ADCP current meter brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth considering. It is made of all - titanium alloy material and offers an excellent cost - performance ratio. You can find more information on their website: https://china-sonar.com/.

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