How to Measure the Coastal Currents of Fujairah?

1. Where is Fujairah?

Fujairah is one of the seven emirates that compose the United Arab Emirates and is located on the eastern coast of the Arabian Peninsula, facing the Gulf of Oman, hence its importance as a hub in the sea.

To the west, the emirate is flanked by the Hajar Mountains, forming a dramatic contrast with the coastal areas facing the Gulf of Oman. It has sandy beaches and rocky shores, with a coastline punctuated by natural harbors. This area combines a most inhospitable arid landscape with a rich marine environment. Different species of fish, turtles, and coral are found in the waters of the Gulf of Oman off Fujairah.

A huge shipping and trade facility, the port of Fujairah is one facility that receives a great volume of cargo. Tourism is on the increase in this emirate, with major attractions including the beaches and water-based tourism activities like diving and fishing.

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

In Fujairah coastal waters, the currents are induced by several factors. The main influences include tidal currents. Because of the gravitational pull from the moon and sun, tides in the Gulf of Oman usually result in a periodic rise and fall. The tidal range and the strength of the tidal currents may vary with the lunar cycle and local bathymetry.

The wind-driven currents also play an important role. The prevailing winds in the area can push the surface waters and create surface currents. The direction and strength of these winds may change with the seasons, which has a consequential effect on the circulation patterns along the coast. The monsoon winds are especially influential during certain months of the year.

Underwater topography around Fujairah. These ridges, channels, and shoals underwater also contribute to altering and diverting the flow of water. In topographic areas of relatively shallow water, the rate of currents may be brought down to slow pace whereas in deeper channels, the currents might get increased dramatically, establishing fairly complex and dynamic current regime.

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

The buoys in this method are deployed at the water surface that are allowed to drift with the currents. Generally, these buoys are equipped with GPS or some other tracking devices. By tracing the position of the buoys as a function of time, the direction and velocity of the surface currents can be measured. This method provides essentially the characteristics of the surface layer only, not a detailed understanding of the vertical structure of the currents.

Anchor Ship Method: Under this method, a ship is moored at some particular point near the Fujairah coast. Instruments such as current meters are attached to this ship, which measure the water flow in the areas surrounding it. As effective as this might be in giving quite accurate measurements within a small radius around the ship, it lacks the capability to cover large expanses and depth levels simultaneously.

ADCP is a more effective and efficient method of measurement of coastal currents. It makes use of the Doppler effect by measuring the velocity of water within the water column at different depths. This technique emits acoustic pulses into the water and measures the frequency shift of the reflected signals by moving water particles. This shows a detailed understanding of the current vertical profile from the surface to the seabed.

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

The working of ADCPs is based on the Doppler principle. Transducers fitted on ADCPs emit acoustic pulses into the water. Due to the Doppler effect, when these sound waves are reflected back after striking the moving water particles, the frequency of the reflected waves shifts. The frequency shift is proportional to the velocity of the water particles relative to the ADCP.

Usually, ADCPs have several transducers that are used to measure water velocity in different directions. The ADCP estimates the three-dimensional velocity of the water, that is, east-west, north-south, and vertical directions, by emitting pulses in different directions and analyzing the frequency shifts of the reflected signals. It also measures the time taken by the sound waves to travel from the transducer to the water particles and back. This, together with the frequency shift, is used in an accurate determination of speed and direction of the water flow at different depths.

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

To have quality measurement of coastal currents, particularly for Fujairah, a number of characteristics needs to be instilled into the equipment. The material applied on the equipment should be trusted, with a guarantee for harsh conditions at sea. It should be compact with minimal weight for easy laying and retrieval. The equipment will also need to focus on low power consumption in case operation is to be performed over a long period, sometimes continuously.

The casing of the ADCP shall be of a titanium alloy. In the saline environment of the Gulf of Oman, corrosion resistance is very important, and this property belongs to the titanium alloy. It also has an excellent strength-to-weight ratio so as to provide durability with relatively lighter equipment. It will also be able to stand pressure changes associated with different water depths.

6. Selection of the Right Equipment: How to?

For the selection of the right equipment in current measurement, the following things are to be kept in mind.

There are many kinds of ADCPs for different purposes. A shipborne ADCP is a quite suitable piece of equipment to be installed on a vessel. It is capable of making measurements while the ship is in movement; thereby wide areas of coastal waters could be covered. A bottom-mounted ADCP is fixed on the seabed and provides stable measurements of the currents passing above it. It is ideal for long-term monitoring at a specific location. A buoy-mounted ADCP combines advantages of mobility and ease of deployment, allowing measurements in different areas.

For the ADCP frequency, it will depend on the water depth. In water with a depth up to 70m, one can work with a 600kHz ADCP because of the shallow water that requires high resolution. In such cases where the depth goes up to 110m, an ADCP with 300kHz is better suited. For deeper waters, such as those near 1000m, the frequency recommended is a 75kHz ADCP. This will allow the measurements over a big vertical range with great accuracy.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option with good quality, the China Sonar PandaADCP is worth considering. It is made of all - titanium alloy material and offers an excellent 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 moels.