How can we measure the coastal currents of Duqm?

1. Where is Duqm?

Duqm is a hidden treasure of the coastline, set in an area of strategic significance with breathtaking landscapes. It stands out as one part of the world that melds together sandy deserts and open waters. The city rests along the Arabian Sea, which boasts an enviable maritime history filled with all kinds of different species.

The surroundings of Duqm combine the sandy deserts, stretching further inland, thereby creating a striking contrast to the blue waters of the sea. This jarring combination lends a special character to Duqm. The seas contain a lot of fishing activities for the local fishermen who have long depended on the beneficence of the sea. The gulf near Duqm presents a haven for different species of fish and other marine organisms, making it a vibrant ecosystem.

Duqm is a budding hub as far as human presence is concerned. It is fast developing as far as infrastructure is concerned, with ports and industrial zones coming up in the last couple of years. The local culture is influenced by the sea through a history of seafaring and trade. Life here is different, with traditional fishing villages abiding amidst modern industrial developments. The coastal areas dotted with small settlements where the residents live in a tight-knit community and with a close love for the sea.

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

Various factors influence the coastal currents at Duqm. A big influence on the tides in this area includes tidal forces. Tides around this area are created by gravitational attraction from the moon and the sun. It is these regular forces which have caused the water to cycle between the tides' fall and rise, therefore contributing to the development of the coastal currents. The ranges in tides can sometimes very powerfully affect the strength and the direction of such currents.

And not the least are the winds. The monsoon winds that blast across the Arabian Sea can have an invigorating effect on surface currents. During the full swing of the monsoon season, strong winds could advance water bodies in a particular direction to create powerful and persistent currents. Besides, the general local wind patterns throughout the year could also change to result in different conditions of currents.

More important, bathymetry of the seabed. Generally speaking, asperity of any sea bottom can deflect and channel the water flow. In this case, the submarine ridge or trough will make current speed or change its direction since it has to flow around those features.

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

Surface Drifting Buoy Method

It is a technique where buoy deployments are made at the water's surface. These buoys are allowed to freely drift with the currents of the surface. Through tracking these floating buoys, over a given period, normally with tracking systems or positioning technology normally based on satellites, it is possible to acquire details about the direction and speed of the surface currents. However, this provides only a partial perspective of the overall water flow, since the methodology is primarily focused on the surface layer.

Anchor Mooring Ship Method

Here, a ship is anchored at a specific location in the coastal waters. Instruments are then deployed from the ship to measure the water flow at different depths. This enables a more detailed understanding of the current at a particular point in the water column. But it is a relatively static method and may not capture the full complexity of the coastal current patterns that can vary over a wide area.

Acoustic Doppler Current Profiler (ADCP) Method

It is a far advanced and highly efficient way of measurement of coastal currents. It makes velocity measurements of water at several water depths simultaneously. A number of sound waves emit their reflection, which includes a Doppler shift to analyze the speed and direction of water movements. This gives a detailed profile of the current through the water column and, since the ADCP may be mounted on one of a number of different platforms including boats or buoys, it is movable to allow broad area coverage.

4. How do the ADCPs employing the principle of the Doppler effect work?

The basic principle behind ADCPs is the Doppler effect. These devices emit an acoustic signal into the water. This signal has a changed frequency by the Doppler effect as a result of interactions with the moving particles of water. This change in frequency is measured and then converted to velocity relative to the instrument by the ADCP.

Given that ADCPs have the potential to transmit signals at varied angles and frequencies, the latter devices are able to measure the velocity components in various directions, including horizontal and vertical, and even at depth. This gives them the capability to build up a rather detailed profile of the water flow from the surface to a certain depth. The data obtained may give a clear picture of the coastal current structure and dynamics.

5. What is required for high-quality measurement of the Duqm coastal currents?

To conduct high-quality measurements of the coastal currents around Duqm, specific features of equipment are necessary. First and foremost, the materials used in this equipment must be reliable. Considering such factors as saltwater corrosion, high humidity, and wave impacts that exist in a marine environment, the equipment should be resistant to them.

The equipment should also be small, lightweight, and light on power consumption. It is easier to install or move a small and light device to any location, whether on a boat or on a buoy. Small consumption means longer operation without frequent battery replacements or heavy power supplies.

Cost-effectiveness is also another important factor. For large-scale measurements, which are necessary to understand the complex current patterns in the coast, the equipment should be affordable to allow several units to be deployed.

In the case of an ADCP, a good choice would be a casing made from a titanium alloy. The corrosion resistance of this alloy is excellent-something important in a saltwater environment. It also has a high strength-to-weight ratio, affording great protection for the internal components while maintaining low overall weight.

6. How to Choose the right equipment for current measurement?

Based on Usage Purpose 

• Ship - borne ADCP: Best used for when one wants to make measurements of the currents as the ship is underway. The instrument can keep on measuring continuously when the ship cruises down the coast, offering the broad overview of current variation on a route.
• Bottom - mounted ADCP: Suitable for fixed-point monitoring at a specific location on the seabed, it will give highly detailed, long-term data about the current conditions directly above its position and thus is very helpful in understanding local flow patterns.
• Buoy-mounted ADCP: In situations when the goal is to cover a wide surface area of the water and extended periods without necessarily being tied up with the ship or bound by the bottom fixation, then one must avail of the services offered by the buoy-mounted ADCP.

According to the Water Depth

• In water as deep as 70m, a 600kHz ADCP is appropriate. It can provide very accurate measurements with good resolution in shallower coastal waters.
• A 300kHz ADCP will be appropriate for water depths up to 110m, which allows for deeper penetration through the water column and will still be able to acquire reliable velocity data.
• For deeper waters, to about 1000m, a 75kHz ADCP is optimum to measure the currents effectively from those greater depths.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, there is also a Chinese ADCP brand, China Sonar PandaADCP, that is 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.