How to measure Safaga's coastal currents?

1. Where is Safaga?

Safaga is a port city in Egypt, and it faces the Red Sea. It is enveloped by arid mountains on one side and the glittering waters of the Red Sea on the other. This location makes the place a perfect site for maritime and trade activities.

The Safaga coastline comprises a beautiful combination of sandy beaches combined with rocky shores. In fact, these waters of the Red Sea are known to have very high biodiversity. Indeed, the coral reefs are quite extended here and act as a haven for several forms of marine life. Practically, everything from tiny reef-dwelling fish to the large pelagic fish can be found here. Besides these, the other marine organisms such as sea urchins, starfish, and different mollusks also contribute toward ecological richness.

Safaga is a very important port town in human activities: great shipping, with all kinds of goods, including foodstuffs; tourism plays a vital role, attracting divers and water-sports lovers thanks to its clear waters and lively underwater world. Fishing is another well-known activity whereby local fishermen depend on the richness of the sea for survival.

The adjacent Red Sea waters have a very peculiar circulation pattern. The general circulation features of the area are controlled by the particular linkage of the Red Sea with the Indian Ocean through the Bab - el­Mandeb Strait. The additional impact on water movement is involved by the local topography of the coast, including coastline curvature and underwater relief with reefs and canyons.

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

A number of factors control the coastal currents around Safaga. The general large-scale circulation of the Red Sea is one such factor; the inflow of water from the Indian Ocean into the Bab-el-Mandeb Strait, with thermohaline circulation driven by differences in temperature and salinity, delineates in general the flow pattern affecting coastal currents.

Wind is another factor. The winds that blow across the Red Sea can drive the surface currents. For example, the northerly or southerly winds during specific seasons may push the water along the coast and either strengthen or alter the existing current patterns. Another important determinant is the topography of the seafloor near Safaga's coast. The underwater ridges, canyons, and shoals may be responsible for changing the direction and speed of water while flowing.

Changes in tides, which depend upon the gravitational pull by the moon and the sun, are also significant. In the coastal areas around Safaga, tidal currents have been pretty strong in bays and inlets. These tidal currents are interlinked with other factors in producing a complex and dynamic pattern of water movement.

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

Surface Drifting Buoy Method

The principle behind this is to deploy buoys on the surface of the water and let them drift freely with the currents. With satellite tracking systems or other means of positioning, it is possible to record the path of the buoys over time, obtaining a record not only of the direction but also of the speed of surface currents. However, that again would merely deal with the surface layer and possibly would be incomplete information about currents within a water body at different depths.

Moored Ship Method

In this technique, a ship is moored at a certain position in the coastal area. The instruments aboard the ship are used for measurements of the characteristics of the water flow in the surrounding area. This technique can also be quite accurate for the area over which the ship is placed, but is nevertheless limited. The presence of the ship may alter the local flow, while the spatial coverage is restricted to the area around the anchored ship.

Acoustic Doppler Current Profiler (ADCP) Method

The ADCP method of measurement is far more effective and efficient. It measures the acoustic waves, which give the water's velocity at different depths. ADCP works on the principle of emitting acoustic pulses and analyzing the Doppler-shifted reflected signals to return a current profile from surface to a certain depth in detail. This allows for a more comprehensive understanding of the vertical structure of the coastal currents near Safaga and is less affected by external factors such as the ship's influence.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of the Doppler effect. These instruments send acoustic signals into the water, which are reflected back by the moving particles in the water-sediments, plankton, or small organisms-and the frequency of the reflected signal is changed. The change in frequency is proportional to the velocity of the moving particles.

It has several transducers emitting and receiving acoustic signals in various directions. This way, by means of the Doppler shift in multiple directions, it is able to estimate three-dimensional space water velocity components. These velocity components, when integrated, give the overall flow velocity magnitude and direction at various depths.

5. What's needed for high - quality measurement of Safaga coastal currents?

The equipment for measuring the currents in Safaga should be manufactured using reliable material for high-quality measurement. It needs to be able to bear the harsh marine environment, such as the corrosive effect from seawater and high pressure at great depth. A small size with light mass is preferable. This helps during the deployment of the equipment on either a buoy, a small boat, or even a fixed platform.

The power consumption should be low, especially in case long-term monitoring is required; the equipment should be capable of working on small power sources, like batteries or solar panels. Low cost is another factor. In order to provide large-scale measurements along the coast of Safaga, the equipment should not be too expensive.

In the case of ADCP casing, titanium alloy is a great material. Therefore, it contains high resistance to corrosion, which is very necessary to bear the corrosive seawater. Its strength-to-weight ratio is also very high, ensuring strength with lightweight. The material will be able to survive quite a long time in a high-pressure environment at greater depth, which is going to assure the equipment reliability during deep water measurement.

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

According to the Usage Purpose

• Shipborne ADCP: In case one intends to measure the currents when the ship is in motion, or during a specific voyage along the coast of Safaga, a shipborne ADCP will suit. It is installed on the hull of the ship and, therefore, collects data while the ship is under sail. Bottom-mounted ADCP: If the monitoring is required over long periods at a fixed location in the currents near the seabed, then a bottom-mounted ADCP is the alternative. This can be fixed with its base on the seabed and provides quite accurate information regarding the flow of water at the bottom.
• Buoy-mounted ADCP: When the goal is to measure the currents at different depths in a more flexible manner and over a wider area, a buoy-mounted ADCP is preferable. It can drift to some degree with the currents and collect data while it moves.

According to Different Frequencies

• The 600kHz ADCP can serve best in water of depth up to 70m, giving highly resolved measurements that can be suitable for quite shallow coastal waters off Safaga.
• Bottom-tracking in water with a depth between 70m to 110m would be much better served with a 300kHz ADCP, which allows an adequate compromise between range and accuracy over medium-depth waters.
• For deeper waters, up to 1000m, a 75kHz ADCP is recommended. It can penetrate to greater depths and provide reliable current data in the deeper parts of the Safaga coastal area.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth considering. It is made of all - titanium alloy, which provides excellent durability. It also offers an impressive cost - performance ratio. You can find more information on its website: https://china-sonar.com/.

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