How to Measure the Coastal Currents of Qinhuangdao?

1. Where is Qinhuangdao?

Qinhuangdao is a coastal city in Hebei Province, China. It nestles on the northeastern coast of the Bohai Sea. The beaches are lovely with good weather conditions and historical value. This town serves both as an essential port and as a tourist destination.

The climate is a warm-temperate monsoon climate with mild winter and warm summer. As influenced by sea breeze, which has moderating influences on the local temperature, Qinhuangdao enjoys comfortable climates. Qinhuangdao has a moderate rainfall and hosts varieties of vegetation, ranging from coastal forests to gardens.

Qinhuangdao has a long sea history. Due to this fact, its local harbors have been used for a long time as the entrance points to the two countries for trade and transportation purposes. The architecture and the culture of the city also reflected its maritime legacy, with ancient forts and seaside resorts.

The adjacent Bohai Sea constitutes an integral part of Qinhuangdao's identity. The bottom topography of the waters around Qinhuangdao is complex in nature; it is characterized by shallow water near the coast and deeper water further out. The tides, winds, and currents over the Bohai Sea are the significant forces that affect its waters.

2. What is the situation of coastal currents around Qinhuangdao?

A number of factors influence the coastal currents around Qinhuangdao. First, there is the main factor-the monsoon climate. The southeast monsoon during summer is strong and can push the surface waters, which again modifies the direction and strength of the coastal currents. The winds push the water to form a pattern which in turn could affect shipping, fishing, and other marine activities. In winter, because of the northwest monsoon, the current directions and speeds are different.

Sea bottom topography is one such contributor to making the difference. Submarine ridges, troughs, and shoals are various features which may result in different current behaviors. Shallow areas may have currents that move slower, while deeper regions with complex seabed structures can have stronger and more variable flows. The water can slow down near the shoals due to the shallower depth, and in the troughs, it can be more intensive and with a more complex pattern of circulation.

Another important factor is tides. The Bohai Sea has regular tides, with their ebb and flow capable of giving rise to considerable tidal currents. In most instances, these tidal currents are most pronounced around estuaries and narrow channels. They are responsible for the essential task of sediment, nutrient, and even marine organism transport. These tidal currents, in turn, influence coastal erosion and sediment deposition and are thus responsible for the shape of the coastline and the distribution of marine life.

Besides, there is also a slight modification of this current through interaction with larger-scale ocean currents from the Bohai Sea and other adjacent areas. Some of these oceanic currents are capable of introducing waters of different characteristics such as temperature and salinity into this area, which would then modify current dynamics along the coast. Intrusion of warmer or colder water masses can alter the temperature of the coastal waters; this often impinges on the local marine ecosystem and weather conditions.

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

Accurate measurement of coastal currents in Qinhuangdao becomes very important for many purposes related to marine safety, fishery management, coastal protection, etc. Traditional methods for observing the flow of coastal water included buoys and current meters, which had applications centuries ago. However, these traditional observation methods could only cover small areas or along coastlines and lacked high precision.

It has evolved that ADCP profiler is a more sophisticated and easy way of measuring coastal currents. The principle behind the measurement of the velocity of water flow in ADCP meter is that of the Doppler principle.

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

ADCP flow meter emit sound waves into the water. These sound waves interact with and meet the moving particles of the water-suspended sediments and other small organisms, for example. Due to the movement of these particles, the frequency of the reflected sound waves will change. This frequency shift is proportional to the velocity of a current.

The sending and receiving directions of the sound wave are different for the transducer array. Through an analysis of the frequency shift of the reflected wave, ADCP doppler could calculate the speed and direction of the current in various directions at different depths. That allows a three-dimensional understanding of the current structure.

3.2 What's needed for high-quality measurement of Qinhuangdao coastal currents?

A number of factors are necessary for excellent measurement of the coastal currents in Qinhuangdao. First, there is a need to guarantee the reliability of the equipment. The ADCP current meter should be fabricated from materials that can resist the harsh marine environment.

One of the best materials for making the casing of ADCP current profiler is a titanium alloy; it is very resistant to corrosion. This is an important factor in saltwater conditions like those on the coast. It resists corrosion by seawater and attack from marine organisms, helping the equipment to perform for many years. Titanium alloy has extraordinary strength while the material remains light. Its strength makes it survive the physical strains in the marine environment, and its light weight also makes it easy to handle and install.

Besides reliability, other features like small size, low weight, low power consumption, and low cost are also quite advantageous. A compact and lightweight ADCP is easier to carry and deploy, and this enables measurements in more locations. Low power consumption allows for longer operation without the frequent need to replace batteries or use large power supplies. The cost-effectiveness is important for large-scale deployment so that the monitoring of the coastal area can be more extensive.

3.3 How to Choose the right equipment for current measurement?

A few of the key factors that are very crucial for choosing the proper equipment in measuring the coastal currents in Qinhuangdao need to be considered. In choosing the right equipment, the intended use plays a key role.

The measurements from a moving vessel can be done with an appropriate ship-mounted ADCP. Then, it may deliver real-time current data as it moves across the coastline, thus enabling constant monitoring of the conditions.

If the measurement needs to be done from a fixed location on the seabed, then it should be done using a bottom-mounted ADCP. It can thus be installed at that location and provide long-term stable current measurements at that location.

In places where applications in open water or the installation of a fixed device is not possible, the buoy-mounted ADCP can be utilized. It measures current over a greater area and wirelessly transmits the data.

In general, the choice of frequency corresponds to different water depths: for water depths up to 70 meters, a generally suitable ADCP is that operating at 600 kHz; for shallower water within the range of 70-110 meters, a 300 kHz ADCP will be more appropriate, while in deeper waters reaching up to 1000 meters, a 75 kHz ADCP 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 ChinaSonar 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 moels.