How to measure the coastal currents of Taizhou?

1. Where is Taizhou?

Taizhou, a seaside city, lies in eastern Zhejiang Province, China, with a long beautiful coastline along the East China Sea. The position of the city is crucial from a geographical point of view, considering it links land and sea.

The Taizhou climate is a subtropical monsoon climate. In summer, it is warm and humid, while in winter, it is relatively mild. Abundant rainfall and sunshine throughout the year give way to a lush and varied natural environment. There could be varieties of plants and wildlife in the area, with coastal wetlands presenting an important ecological niche.

Taizhou also possesses a great many cultural and historical heritages. Local people in the city have special customs and traditions passed down generation by generation. Its handicrafts and food are very well-known within the nation. Fishing and maritime industries have a long history here; therefore, they constitute one of the key elements in the local economy.

Regarding this fact, for the East China Sea alone, it refers to waters adjacent to Taizhou. These waters are not only used for fishing purposes but also for shipping and other forms of maritime activities. From a morphological perspective, the sea floor along Taizhou is irregular in nature, containing shelves intermitted by submarine ridges and troughs. Consequently, this variability in morphology further controls the distribution of marine resources and the flow of water.

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

The coastal currents around the area of Taizhou are influenced by many factors. First, there is a monsoon system. During summer, the southeast monsoon brings warm and moist air into the atmosphere that can drive the surface waters and hence influences the direction and strength of the coastal currents. In winter, the prevailing wind is from the northwest monsoon, which again changes the pattern of the currents.

Topography is also one of the very important factors in this regard. Underwater ridges and troughs can further disturb the flow of water so that it may flow in different directions with different speeds. Shallow areas may have slower currents, while those with deeper troughs can have stronger and more complex flows.

The other relevant factor involves tides. Driven by the ebb and flow of the East China Sea, normal tidal motions are widespread and generally lead to heavy tidal currents. Generally speaking, the range of tidally induced current movements is usually larger in areas near estuaries and narrow channels. Tidal currents take priority in sediment transport and nutrient movement; hence, they have a direct impact on marine organisms' growth and distribution, and a indirectly on the stability of the coastal environment.

Besides, the interaction with larger-scale ocean currents from the Taiwan Strait and other adjacent areas can further modify the coastal currents around Taizhou. Water masses with different temperature and salinity values advected by these oceanic currents can also affect the local current dynamics.

3. How to Observe the Coastal Water Flow of Taizhou?

Precise measurement of the coastal currents in Taizhou is an indispensable requirement for a wide range of applications related to marine safety, fishery management, and environmental protection. Traditional coastal water flow observation depends on methods such as buoy and current meters, which have existed for a long period. However, these observation techniques are substantially limited in their effectiveness in terms of accuracy and coverage.

Acoustic Doppler Current Profilers have been a more advanced and convenient means of measurement of coastal currents. These ADCP current meter measure the velocity of the flow of water by utilizing the Doppler principle.

3.1 How do Acoustic Doppler Current Profiler(ADCP) using the Doppler principle work?

These are ADCPs that send sound waves into the water. These sound waves would interact with the moving particles in the water, including the suspended sediments and small organisms. Because of this interaction with the moving particles, the frequency of the reflected sound waves is altered as they move. The change in frequency is dependent upon the velocity of the water current.

An ADCP doppler sends and receives sound signals in multiple directions from its transmitter. After processing the frequency shift of the reflected waves it has sent and received at varying directions, this device calculates the current speed and direction at different depths. Thus, the ADCP can perceive the current structure three-dimensionally.

3.2 What is required for fine measurement of the Taizhou coastal current?

High-quality measurement of the coastal currents in Taizhou will consider a number of factors. The first is the reliability of the equipment. The ADCP flow meter should, to this end, be made of materials that can resist the harsh marine environment.

Titanium alloy can be a great material for ADCP meter casing since it is extremely resistant to corrosion, an important factor in the salt-water environment of the coast. It resists the corrosive activity of seawater and marine organisms, hence guaranteeing long-term performance of equipment. Besides, the titanium alloy is strong yet lightweight. The strength allows it to bear the physical stresses experienced within the marine environment, while the light weight eases handling and installation.

Apart from material reliability, other features like small size, low weight, low power consumption, and low cost are desirable. A small and lightweight ADCP profiler is easier to handle and deploy, extending the possibility of measuring over a greater number of sites. Low power consumption allows the instrument to operate for longer without changing the batteries frequently or having a large power supply. This is cost-effective for large-scale deployment and can monitor a larger coastal area.

3.3 How to choose the right equipment for current measurement?

While the selection of the right equipment for the measurement of the currents in the coast of Taizhou is concerned, a number of factors are to be considered. One of the key factors will be the use the equipment is put to,.

For measuring from a vessel underway, a ship-mounted ADCP is very convenient. With the vessel underway along the coast, it measures real-time current, hence enabling the continuity in monitoring conditions of the current.

It should be noted that if the measurement has to be done at a fixed place on the seabed, then it should be done using the bottom-mounted ADCP. Thus, it can be installed at a fixed point and give long-term stable measurements of the current there.

A buoy-mounted ADCP can be used when operating in open water or where a fixed installation is impracticable. It can measure current in a much larger area and send the data wirelessly.

For the selection of frequency, the different water depth allows different frequencies. For waters up to a depth of 70 meters, a 600 kHz. ADCP will generally be appropriate. For waters between 70 and 110 meters, an ADCP of 300 kHz will be more appropriate. For deeper waters of as much as 1000 meters, frequencies of 75 kHz should be considered.

When it comes to choosing an ADCP brand, well - known international brands such as Teledyne RDI, Nortek, and Sontek are popular options. However, for those seeking a cost - effective yet high - quality alternative, the China Sonar PandaADCP is worth considering. Made entirely of titanium alloy, it combines durability and reliability with an excellent price - performance ratio. You can find more information about it at https://china-sonar.com.

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