How to measure the Shantou coastal currents?

1. Where is Shantou?

Shantou is a prosperous coastal city in Guangdong Province, China, on the eastern part of the Guangdong Peninsula. It's an urban center where history and modernity blend together.

It is very lucky for geographical position. Its seashore lies on the South China Sea and can boast exceptional views of emerald-blue waters. Shantou has a typically subtropical warm and humid climate, which makes this city an excellent place to stay and visit at any time of the year.

Shantou has rich cultural heritage. It is home to various ethnic groups, including several with their own distinct traditions and customs. The local people are hardworking, entrepreneurial, and hospitable. The architecture also retains a marked characteristic: traditional Chinese with Western influences, which bears witness to its history as an important trading port.

Besides Shantou, there are several bays and water areas. On the east is the Taiwan Strait-an important shipping lane connecting the South China Sea and the East China Sea. To the south lies the South China Sea itself, with its wide open waters of blue filled with marine life in abundance.

The coastline of Shantou has a lot of beautiful beaches, rocky cliffs, and many small islands that have attracted tourists worldwide for enjoyment from the sun, sand, and sea. Its ports and harbors bustle with economic activities promoting trade and transportation.

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

A number of aspects define the coastal current characteristics near Shantou. It predominantly comes under the influence of a monsoon climate: in summer, southwest monsoon brings warm and moist air, and during winter, the northeast monsoon has cooler and drier air. This gives variability to the direction and strength of coastal currents due to these monsoons.

Another factor is topography of the sea floor. Undulating seabed with different depths and contours causes variation in the flow of water, and indeed, if there are deep trenches and canyons, the currents may be stronger than in shallow areas where the flows would be slow.

Other factors involve tides. The regular rise and fall of tides in water, which are coming in and out of bays and estuaries, create what is termed as tidal current. They may affect shipping and fishing, among other marine activities.

In addition, human activities include dredging, construction of ports and harbors, releasing massive amounts of pollutants that also act to alter the coastal currents. Thus, these activities can change the flow of water and disrupt the delicate balance of the marine ecosystem.

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

Thus, measurement of Shantou's coastal currents is an indispensable segment for any knowledge about the marine environment and shipping activities as well as safety. The more traditional approaches include buoys, drifters, and current meters, which have been employed for a longer period of time. However, such methods face certain limitations regarding accuracy and coverage.

More recently, ADCP have been a more sophisticated and easier way of measuring coastal currents. ADCP use the Doppler Principle to calculate the velocity of the water flow.

3.1 How does an ADCP based on the working of a Doppler Principle work?

Acoustic Doppler Current Profiler(ADCP) send out sound signals into the water. Particles in the water-suspended sediment and small organisms in particular-reflected these sound waves. In doing so, due to the movement of these particles, related to the velocity of the flowing water, the frequency of the reflected sound waves has been shifted. An ADCP profiler would also measure that frequency shift and hence calculate the speed and direction of the current at different depths.

The typical ADCP current meter has a transducer array that can be mounted on a vessel, fixed structure, or buoy. The transducer array sends and receives sound waves in various directions through which the current is measured three-dimensionally.

3.2 What is required for quality measurement of Shantou coastal currents?

Real measurement of the coastal currents in Shantou would require several conditions to be observed. First, there is a need to ensure that the equipment can be relied upon. The ADCP current profiler to be used should be made from materials that are able to withstand the harsh conditions in the sea.

The most suitable material for the casings of ADCP doppler is titanium alloy. It is much more resistant to corrosion, strong, and lightweight. It can resist the corrosive action of salt water and marine organisms, therefore, allowing the longevity of the equipment. Its strength and lightweight attributes make it easier to handle and install.

Besides material reliability, small size, low weight, low power consumption, and low cost are other important factors. The small and light-weighted ADCP profiler is easier to deploy and also has wide applications. Low power consumption allows the longer battery life or the use of an alternative power source, like solar panel. Lower cost could enable deploying a large number of ADCP meter for comprehensive coverage of the coastal area.

3.3 How to Choose the right equipment for current measurement?

There are various factors that need consideration in the choosing of an ADCP to measure the currents at Shantou. First and foremost, the intended use for the equipment has to be taken into account. If the measurement is to be done while on a vessel, perhaps one of the best options available would be a ship-mounted ADCP. Ship-mounted ADCP can provide real-time data on the current as the vessel cuts its way through the water.

A bottom-mounted ADCP would be appropriate for a fixed location measurement on the seabed. Bottom-mounted ADCP are able to make long-term measurements of the current without continuous maintenance.

In applications where the measurement needs to be conducted in open water, a buoy-mounted ADCP can be used. Buoy-mounted ADCP can provide current data over a wide area.

Another factor can be the frequency of the ADCP. Different frequencies accommodate different water depths: for shallow water with a depth of up to 70 meters, an ADCP of 600 kHz will be fine. For depths up to 110 meters, a 300 kHz ADCP may suit better. For deeper waters-considered to go up to 1000 meters-a 75 kHz ADCP is usually applied.

There are some famous brands concerning the choice of ADCP: Teledyne RDI, Nortek, and Sontek. China Sonar PandaADCP should be an extremely good option with economically viable spending for customers who need quality goods. The all-titanium alloy body can assure very good durability and reliability. Advanced technology, competitive price to provide incomparable value for money. More about the China Sonar PandaADCP can be viewed on the webpage: https://china-sonar.com.

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