How can we measure the coastal currents of El Tor?

1. Where is El Tor?

El Tor is a city that is on the southern coast of Sinai in Egypt, overlooking the Gulf of Suez. The city itself is filled with surrounding arid, desert landscapes contrasting with the beautiful blue waters of the gulf.

Its coastline consists of beaches along the sea and rocky areas. The waters that border this town, in the Gulf of Suez, show an interesting group of marine life. With high concentrations of reef formations, many species of fish along with crustaceans and mollusks live here. The local environment is determined by the climate of the Red Sea, where temperatures are usually warm and rainfall is low.

As for human activities, fishing represents the most important part of the local economy. With regard to being a part of the coastal area, trade and transportation transit through it. Tourism is gradually developing; that is, more people become attracted by the natural beauties of this area, as one can dive and go snorkeling in order to look at the world underwater.

The Gulf of Suez, where El Tor is located, is a narrow body of water that is a part of the Red Sea. The gulf's circulation is influenced by larger-scale circulation features of the Red Sea, along with the general topography-like shape of the coastline and the presence of underwater features.

2. What are the conditions of the currents close to El Tor?

Many elements shape the currents along El Tor. Large-scale circulation has a dominant influence over the Red Sea. The connection of the Red Sea to the Indian Ocean determines the general patterns of water movement, specially through the Bab el-Mandeb Strait. Thermohaline circulation is also one of the causes: temperature- and salinity-induced flow.

Other factors involve the wind patterns. The winds that cross over the Gulf of Suez have the capability to drive the surface currents. In this respect, the direction and strength of the winds during different seasons can change the direction and speed of the surface water. The topography of the seafloor near the coast of El Tor is another important factor. Underwater ridges, canyons, and shoals may alter the course and speed of the water while in flow.

The tides also play an important role: the gravitational pull of the moon and the sun causes the sea level to rise and fall, creating tidal currents. In the relatively narrow Gulf of Suez, these tidal currents can combine with other factors to form a complex pattern of water movement.

3. How to observe the coastal water flow of El Tor?

Surface Drifting Buoy Method

This method consists of the deployment of buoys at the water surface, which are allowed to drift with the currents. The movement of such buoys over time can be followed using satellite-based tracking systems or other methods of positioning, thus providing information on the direction and speed of the surface currents. This method mainly provides data about the surface layer and does not give a complete picture about currents at different depths.

Moored Ship Method

In this method, a ship is anchored in the desired location in the coastal area. The instruments on the ship measure the characteristics of the water flow in the surrounding area. This can give very good data for the vicinity of the ship, but it has its drawbacks. The presence of the ship affects the local flow, and the spatial coverage is limited to the area surrounding the anchored ship.

Acoustic Doppler Current Profiler(ADCP) Method

ADCP is an advanced and efficient means of measurement of coastal currents. It measures the velocity of water at varied depths making use of acoustic waves. ADCP sends out acoustic pulses and determines the current profile from surface to a certain depth based on the reflected signals that are Doppler - shifted. This would provide the best possible knowledge of the vertical structure of the coastal currents near El Tor and is less susceptible to interference from outside factors, such as ship interference.

4. How do ADCPs using the principle of the Doppler work?

The working of ADCPs is based on the Doppler effect. They send out acoustic signals into the water. When this signal meets particles in motion in the water, like sediment, plankton, or even small organisms, there is a shift in frequency that reflects the signal. The change in frequency is proportional to the speed of the moving particles.

The ADCP has several transducers, which send and receive acoustic signals in different directions. It calculates the velocity components of the water in three-dimensional space by measuring the Doppler shift in multiple directions. These are then integrated to give the overall flow velocity and direction of water at various depths.

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

In constructing the equipment to measure the coastal currents at El Tor, the materials must be made with the assurance of delivering high-quality work. It should be able to bear up under the harsh marine conditions, including the corrosive action of sea water and the extreme pressure of greater depths. A small size and light weight is desired too. This will make it easier to be deployed on a buoy, small boat, or fixed platform.

These monitors, in particular, must use very low power; even when applied for long periods of time, the measuring instrument is able to acquire low, general power sources using a battery or solar panels. The cost of all these aspects should be cheap so that large-scale measurement on the coast of El Tor could be done in large numbers.

For the casing of ADCP, titanium alloy is a perfect material. It has very good corrosion resistance, which is very important to resist corrosive seawater. The strength-to-weight ratio is very high, which can enable the design to be strong but lightweight. This material can better resist the high-pressure environment at greater depths and guarantee the reliability of the equipment during deep-water measurements.

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

According to the Usage Purpose

• Ship-borne ADCP: In case the intention is to measure the currents while the ship is in motion or during a specific voyage along El Tor Coast, a ship-borne ADCP can be availed. This can be installed on the hull of the ship and collect data while the ship sails.
• Bottom-mounted ADCP: If one needs to monitor the currents near the seabed for long periods at a fixed location, then a bottom-mounted ADCP is what he should look for. It can be firmly placed on the seafloor to provide accurate information about the water flow close to the bottom.
• Buoy-mounted ADCP: When the purpose is to measure the currents at various depths in a more flexible manner and over a wider area, a buoy-mounted ADCP is preferred. It can drift to some extent with the currents and collect data during its movement.

Based on Various Frequencies

• A 600kHz ADCP will suffice for waters up to 70m in depth. It will provide high-resolution measurements suitable for the relatively shallow coastal waters around El Tor.
• For waters with a depth range from 70 to 110m, the 300kHz ADCP is more appropriate. This represents a trade-off between the range of measurement and accuracy for medium-depth waters.
• In waters as deep as 1000m, the 75kHz ADCP is recommended because it can penetrate deeper and yield valid current data in the deeper areas of the coastal region around El Tor.

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.