How are the coastal currents of Lianyungang measured?

1. Location of Lianyungang

Lianyungang is a seaside city in Jiangsu Province, China. The city's location is right at the juncture of Jiangsu's coast with the Yellow Sea. This is just an added advantage in making this city important, being a port city and a leading transportation hub.

All beautiful natural sceneries surround the city. It has a very long and indented coastline with sandy beaches, rocky coasts, and all forms of coastal wetland. The climate of the area is of a temperate-monsoon type. It has mild winters and warm summers; the rainfall is distributed over the year and allows many forms of vegetation and fauna to grow.

Lianyungang represents a city with great depth of history and culture. It has stood abreast with the ocean, sea trade in contact for so many years. The inhabitants preserve their unique traditions and crafts. It is an urban area whose economy relies heavily on its ports, shipping industry, fishing, and chemical industry.

The Yellow Sea next to the area is vast. Besides, the topography of the seabed around Lianyungang is complicated, full of undersea ridges, troughs, and shoals. The water of the Yellow Sea in such an environment is influenced by the river outflows from the inland and oceanic currents from afar.

2. What about the conditions of the coastal currents near Lianyungang?

Different conditions prevail, and the influencing factors include a monsoon climate. During the summer period, Southeast Monsoon brings warm and wet air flow to drive the surface waters; hence it modifies the general direction and strength of coastal currents. During winter periods, the dominant wind is from the northwest monsoon, which changes the prevailing general pattern of currents.

The relief of the bottom topography is not unimportant. In this regard, underwater ridges and troughs may serve to channel the water flow at various intensities and speeds in different ways. Shallower regions, like shoals, may be taken by slower moving currents, while over deeper regions more intensive and complicated flows can be developed.

Another important factor is tides: The regular ebb and flow of the tides can result in considerable tidal currents in the Yellow Sea. Around estuaries and narrow passages, tidal currents are especially very strong. They play a crucial role in the transportation of sediments, nutrients, and marine organisms, which have direct influences on the marine ecosystem and coastal geology.

Besides, it also can be modified by the interaction with more large-scale ocean currents from the Yellow Sea and the Kuroshio Current. That could introduce water masses with different temperatures and salinities into the region and affect the local current dynamics.

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

The precision in measuring the coastal currents at Lianyungang is very necessary for several purposes: marine safety, port operations, fishery management, and environmental protection. Traditional methods involve buoy and current meter observations, which have been in use for a long time. However, these methods have disadvantages with regard to accuracy and coverage.

In more recent times, the measurement of coastal currents has been done in a more sophisticated and easy way using Acoustic Doppler Current Profilers. These employ the Doppler Principle to measure the velocity of water flow.

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

ADCP current meter emit sound waves into the water. In this case, the moving particles in the water, like suspended sediments and small organisms, reflect these waves back toward their origin. As these particles move, the frequency of the reflected sound waves changes. This frequency shift relates to the velocity of the water current.

The transducer array in the ADCP current profiler sends out and receives sound waves in multiple directions. By the frequency shift of the reflected waves in several directions, the ADCP doppler can calculate the speed and direction of the current at different depths. Full three-dimensional mapping of the current structure is thus enabled.

3.2 What is necessary to have a good quality measurement of the Lianyungang coastal currents?

Among several other reasons, equipment reliability is key to such high - quality measurement of the coastal currents in Lianyungang. The ADCP flow meter should be made from materials that can resist the harsh marine environment.

One very good material for the casing of an ADCP meter is titanium alloy. It is very resistant to corrosion, a significant property in saltwater on the coast. It means it can also withstand the various effects of seawater and marine organisms on its performance and hence is able to last longer. Besides, titanium alloy has a strong yet light structure. Its strength will be able to bear all physical stresses in the marine environment, while its lightweight makes handling and installation easier.

Besides material reliability, other features such as small size, low weight, low power consumption, and low cost are also advantageous. A small and lightweight ADCP profiler is easier to carry around and to launch into the water for measurements of more locations. Low power consumption allows longer operation without frequent battery replacement or a large power supply. Another important consideration is affordability, for large-scale deployment to effectively monitor the coastal area.

3.3 How to Choose the right equipment for current measurement?

Selection of the appropriate equipment to measure the currents along the coast in Lianyungang has to be based on several parameters, one of the main ones being the intended usage of the equipment.

A ship-mounted ADCP is quite useful when measurements are taken from a moving vessel. Here, the instrument can provide real-time data on the current while the vessel cruises along the coast, thus providing a continued monitoring of the current conditions.

If the measurement to be done requires a fixed location at seabed, then bottom-mounted ADCP will be a good choice, which can be installed at the desired point and measure the current continuously with long-term stability for that location.

By contrast, an ADCP mounted on a buoy may be used in open water or wherever a fixed installation is impracticable. It measures current over a greater area and wirelessly transmits the result.

As far as the choice of frequency goes, different frequencies apply to different water depths. For as shallow a depth as 70 meters, the 600 kHz ADCP usually applies. Where the depth of water is between 70 and 110 meters, a 300 kHz ADCP should be considered instead. When the bottom topography is such that the waters are deeper than this, going up to 1000 meters, one should consider using a 75 kHz ADCP.

Brands like Teledyne RDI, Nortek, and Sontek are well-known, international brands; however, when it comes to seeking something in the cost-effective quality category, there is the China Sonar PandaADCP. This is made entirely from titanium alloy, for durability and reliability, excellent price, and performance. You can learn more about it at https://china-sonar.com.

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