How do we measure coastal currents of Hurghada?

1. Where is Hurghada?

Hurghada is a busy coastal city that fronts the Red Sea in Egypt. It is one of the favorite tourist spots because of its beaches and crystal-clear waters, home to a wide range of marine life.

The coastline is just this long stretch of beaches with the azure waters of the Red Sea acting as a perfect backdrop. The waters around it contain an incredible amount of coral reefs. They are part of the local ecology and represent a very intricate web, acting as a habitat for an immense number of fish species, from colorful tropical fish to larger ones. Sea turtles and dolphins can also be spotted quite frequently.

Tourism is the mainstay of the local economy in terms of human activities. The city offers a wide range of water-based activities such as diving, snorkeling, and windsurfing. There are resorts and hotels lining the coast, catering to visitors from all over the world. Fishing also plays a role in the local economy, with the bountiful resources of the Red Sea providing a livelihood for many local fishermen.

The Red Sea, in which Hurghada is situated, is a semi-enclosed sea and has its own specific circulation patterns. The local topography of the general shape of the coastline and of underwater features such as reefs and shoals may influence the water movements in the area.

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

The coastal currents near Hurghada are influenced by more factors. First of all, it plays a fundamental role in the large-scale circulation of the Red Sea. The connection between the Red Sea with the Indian Ocean via the Bab el-Mandeb Strait and the inflow through this strait may influence the overall water movement patterns of the Red Sea and, by implication, the coastal currents near Hurghada. The thermohaline circulation, which is driven by the difference in temperature and salinity, affects the pattern of current.

The main factors contributing are the wind patterns. The winds blowing across the Red Sea can drive the surface currents. For example, during summer months, northerly winds can push the surface water in one direction, either enhancing or disrupting the natural flow of coastal currents. The other key factor is the topography of the seafloor along the coast of Hurghada. The underwater features that exist, like coral reefs, canyons, and shoals, can result in the water changing its course and speed as it flows.

The tides are another important factor. By the gravitational pull of both the moon and the sun, the sea level rises and falls and generates tidal currents. In the narrow, structure-complex coastal area off Hurghada, such tidal currents can interfere with other factors in a way that creates a complicated dynamic pattern of water movement.

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

Surface Drifting Buoy Method

It basically consists of the use of buoys deployed on the water surface and left to drift with the currents. Using satellite-based tracking systems or any other positioning methods, which monitor the buoy movement over time, one is able to obtain information on the direction and speed of the surface currents. This method will provide information mostly about the surface layer and not completely about currents at various depths.

Moored Ship Method

With this approach, a ship is anchored in a specific place in the coastal area, with instruments on the ship that measure the characteristics of the water flow in the surroundings. The immediate area surrounding the ship might get very good data; this is a fairly limiting approach since the presence of the ship would interfere with the local flow and spatial coverage was restricted to an area around an anchored ship.

Acoustic Doppler Current Profiler Method

Acoustic Doppler Current Profiler(ADCP) is more advanced and efficient in measuring coastal currents. It makes use of acoustic waves to measure the velocity of water at different depths. In this way, ADCP gives a detailed profile of the current right from the surface to the required depth by emitting pulses of acoustic signal and analyzing the Doppler-shifted reflected signals. This allows for a far better understanding of the vertical structure of the coastal currents near Hurghada and is less exposed to external influences, such as by the ship itself.

4. How do ADCPs using the Doppler principle work?

ADCPs are based on the principle of the Doppler effect. They transmit acoustic signals into the water. As these signals encounter moving particles in the water-like sediment, plankton, or small organisms-the frequency of the reflected signals changes. The change in frequency is proportional to the velocity of the moving particles.

The ADCP has several transducers, which transmit and receive acoustic signals in different directions. The ADCP receives the Doppler shift in various directions and thus can calculate the three-dimensional velocity components of the water. These velocity components are then integrated to determine the overall water flow velocity and direction at different depths.

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

Reliability in the construction materials of the equipment to be used will ensure the high-quality measurement of the currents in Hurghada's coastal waters. It must be resistant to the marine environment: the corrosive action of seawater and, above all, high pressure in the case of greater depths. Small size and low weight are preferable in this regard for easy deployment on either a buoy or a small boat, fixed platforms, among others.

Low power consumption, especially in the case of long-term monitoring, is needed. Equipment should work on small-power sources like batteries or solar panels. Cost-effectiveness is another important point. For performing large-scale measurements along the coast of Hurghada, equipment that can afford such a task is needed.

Titanium alloy is an excellent material when it comes to the casing of ADCP. Since seawater is corrosive, high corrosion resistance is the foremost requirement for the ADCP casing. The high strength-to-weight ratio allows making a strong yet light structure. In this way, it can withstand the high pressure at greater depths and can make the equipment reliable during deep-water measurement.

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

According to the Usage Purpose

• Shipborne ADCP: In case the intention is to measure currents while the ship is in motion or on a voyage along the Hurghada coast, then the shipborne ADCP will be suitable. It can be installed on the hull of the ship and collect data while it sails.
• Bottom-mounted ADCP: An ADCP mounted on the bottom is called for when long-term, fixed-location monitoring of currents near the seabed is required. It could be firmly placed on the seafloor to provide accurate information about the water flow close to the bottom.
• Buoy-mounted ADCP: When the requirement is to measure currents at various depths in a more flexible manner and over a wider area, a buoy-mounted ADCP should be used. It can drift to some extent with the currents and collect data during its movement.

Based on Operating Frequency

• The 600kHz ADCP is sufficient for a depth of 70 m, as it provides measurements in high resolution and at the same time is suited for less deep coastal water near Hurghada.
• For waters approximately between 70m to 110m depth, 300kHz would suit better as that would allow not only more measurements but with sufficient accuracy.
• For waters as deep as 1000m, a 75kHz ADCP would be appropriate; it will penetrate much deeper and yield more reliable current data in deeper areas of the Hurghada 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.