How to Measure Coastal Currents in Kanazawa

1. Kanazawa: Location, Location.

Kanazawa is not a west coastline city from the main island, Honshu, of Japan. Yet again, she is an approximate coastal side city to the Sea of Japan. That historical city had been considered due to their well-preserved architecture of Edo-period origins that also retain beautiful gardens with unique traditional art in gold-leafing.

While it is not directly on the coastline, proximity to the Sea of Japan would mean that the coastal currents can affect the local environment and economy in terms of climate regulation and fishing, among other factors. The local economy is diverse, with sectors such as tourism, traditional crafts, and light manufacturing.

2. The Coastal Currents near Kanazawa

While, of multiple-factor control, the Tsushima Current is a significant factor controlling near-shore currents in Kanazawa. This warm branch of the Kuroshio Current controls the temperature distribution and nutrient supply to all inshore waters of the Sea of Japan.

Tidal currents must also be an important agency of transport. The tidal range in the Sea of Japan is considerable, and the ebb and flow of the tides result in complex current patterns. The shape of the coastline and the underwater topography are important determinants. Bays, headlands, and underwater ridges may be responsible for changes in direction and speed of the currents. Besides, the wind pattern, especially the seasonal wind that blows across the Sea of Japan, can drive the surface current and mix different layers of water.

3. How to Observe the Coastal Water Flow near Kanazawa?

Surface Drifting Buoy Method

A surface-drifting buoy can be released into the water in the Sea of Japan near Kanazawa. The buoy's movement over time can be followed with GPS or other tracking systems. However, this method does have its setbacks. It will only be able to give information on the surface current and might be influenced by wind and waves. For instance, if a strong wind blew the buoy in a different direction from that of the actual current, then erroneous measurements of the current's direction and speed will be the result.

Anchor-Boat Method

The current can be measured by using an anchored boat. Instruments can be lowered from the boat into the water to take the measurements at different depths.

While this method has the advantage of offering more detail in depth, it has disadvantages. The measurement area is restricted by the position of the boat in fixed position and may not indicate the entire variability of currents in a large coastal area.

Acoustic Doppler Current Profiler (ADCP) Method

The Acoustic Doppler Current Profiler (ADCP) method is an advanced and efficient way of measurement of the coastal currents. ADCPs emit acoustic signals into the water and measure the Doppler shift of the reflected signals to calculate the velocity of water at different depths.

This gives a better profile of the current from surface to seabed. ADCPs are less affected by surface disturbances and can operate for long periods continuously, giving a more accurate picture of the current structure.

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

ADCPs operate based on the Doppler effect. They send high-frequency acoustic pulses into the water. Interaction of these pulses with moving water particles changes their frequency of reflection. If the water particles move towards the ADCP meter, then the reflected signal frequency is higher than the emitted one, and if they move opposite, then it is lower.

Several transducers are fitted on an ADCP profiler, which emit and receive signals at various obliquities. This was done by analyzing the various Doppler shifts coming from the different directions at depth. By which, the device would measure the three-dimensional water velocity - that is, both its horizontal and vertical components, the detailed structure of the currents.

5. What is required for high-value measurement of Kanazawa coastal currents?

For high-quality measurement of the coastal currents near Kanazawa, the equipment should have reliable materials. Given the marine environment, with saltwater, potential exposure to storms, and the influence of tides and ocean currents, a durable casing is necessary. The size of the equipment should be small in order to be easily deployed and retrieved, especially considering the complex coastal landscape with its bays and headlands.

A light design is desired since it makes the equipment easier to handle during installation and maintenance. The power consumption should be low for long-term autonomous operation. Cost-effectiveness is also necessary to enable large-scale measurements.

The casing of ADCPs would be made from titanium alloy, which has excellent corrosion resistance necessary to survive the corrosive impacts of seawater. It is tough and durable enough to bear the pressures of water at different depth levels. Its lightweight character makes it more convenient for many deployment methods.

6. How to choose the right equipment for measuring current?

When choosing equipment for current measurement near Kanazawa, consider the purpose of use first. If the measurement is for a vessel's navigation or short - term research, a ship - mounted ADCP is a suitable option. 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 is ideal.

Regarding the frequency of ADCPs, for water depths up to 70m, a 600kHz ADCP is good. For water depths up to 110m, a 300kHz ADCP would be more appropriate. For waters deeper than this, as might be found off Kanazawa, say with depths over 1000m, a 75kHz ADCP is recommended.

There are well-known ADCP flow 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.