1. Where is Qatar?
Qatar is a peninsular country extending into the Persian Gulf in the Middle East. To the south, it borders Saudi Arabia while sharing a maritime border with other Gulf countries in all other directions.
The Qatar landscape is dominated by arid desert plains meeting the shores of the Persian Gulf. Its shoreline contains a number of sandy beaches, salt flats, and some mangrove areas important to the coastal ecosystem. This city is the capital city, Doha, is a modern metropolis filled with iconic skyscrapers and a lively cultural atmosphere.
The waters of the Persian Gulf surrounding Qatar are mostly warm and shallow in many areas. These waters are host to a variety of fish, crustaceans, and different mollusk species. The gulf is also a major shipping lane, with tankers and cargo vessels plying across it day in and day out, since Qatar is a significant player in the global trade of liquefied natural gas.
2. What is the situation of the coastal currents near Qatar?
Various factors shape the coastal currents near Qatar. Tidal currents are one of the prominent influences. In the Persian Gulf, tides caused by the gravitational pull of the moon and the sun are quite regular, with a rise and fall of sea level following each other. The tidal range varies, and the tidal currents may have a great impact on the coastal areas, especially in bays and inlets.
The wind-driven currents also play a vital role in the oceanography of this region. Prevailing winds, such as the Shamal winds which blow from the northwest, have the capacity to push on the surface waters and hence create surface currents. In addition, such winds do have seasonal variations in strength and direction, which alter the coastal circulation patterns.
The submarine topography around Qatar is another important consideration. The features of submarine ridges, channels, and shoals may cause a partial deflection of water flow. Shallow bottoms could reduce the speed in some places while at the same time deeper channels can increase the speed showing a complex dynamic current regime.
3. How to observe the coastal water flow of Qatar?
Surface Drift Buoy Method: This method involves setting buoys on the water surface, which are allowed to drift with the currents. These buoys are usually equipped with GPS or other tracking devices. By monitoring the movement of the buoys over time, the direction and speed of the surface currents can be ascertained. However, this method mainly provides information about the surface layer and may not give a detailed understanding of the vertical structure of the currents.
Anchor Ship Method: In this technique, the ship is anchored at a place, near the coast of Qatar. This ship would carry the instruments of measurement required to be installed on it to measure the flow of water around it. Though very good in certain aspects regarding accurate measurement of water, the method also has drawbacks when it has to take care of an extensive area with varying depth.
This more modern, efficient way to measure coastal currents is called ADCP, or Acoustic Doppler Current Profilers. Similar to the light and sound phenomena one observes in day-to-day activities, the movement of the water in question induces a frequency shift related to the Doppler Effect on the reflected signals and their round-trip speed, with the moving particle speeds giving out the velocity signals from a column of water at variable depths. A given measurement therefore provides a vertically detailed picture of the vertical current profile between surface and seabed.
4. How do ADCPs using the principle of Doppler work?
Working on the principle of Doppler, ADCPs have transducers that emit acoustic pulses into the water. Because of the Doppler effect, the frequency of the reflected waves changes when the sound waves encounter moving particles of water. The change in frequency is proportional to the velocity of the water particles relative to the ADCP meter.
Usually, ADCPs have multiple transducers to measure the water velocity in different directions. By emitting pulses in different directions and analyzing the frequency shifts of the reflected signals, the ADCP current meter can calculate the three-dimensional velocity of the water-that is, east-west, north-south, and vertical directions. This process also calculates the time taken by the sound waves to reach the water particles from the transducer and back for these particles to return to the emitting position. These two pieces of information, along with the frequency shift, enable the precise measurement of speed and direction at various levels of water flow.
5. What is needed for high-quality measurement of Qatar coastal currents?
The equipment for high-quality measurements of coastal currents off Qatar has to be characterized by a number of features. The material of the equipment has to be robust and resistant to the aggressive marine environment. The device has to be compact, with low weight, to enable easy deployment and handling. It also needs to have low power consumption in order for it to operate continuously, especially in long-term monitoring.
The casing of the ADCP current profiler is made of titanium alloy. The material provides excellent corrosion-resistant properties, important in the saline environment of the Persian Gulf. It has a high strength-to-weight ratio, meaning that it will provide durability yet keep the equipment relatively light. This material is able to bear pressure changes associated with different water depths.
6. How to Select the right equipment for current measurement?
While selecting equipment for the measurement of current in Qatar, the following aspects are to be kept in mind.
The usage purpose will help in selecting the type of ADCPs. For example, a ship-borne ADCP is meant for installation on a vessel and can carry out the measurement of currents while the ship is in motion. This will help in covering a major area of the coastal waters. A bottom-mounted ADCP, while fixed on the seabed, provides very stable measurements of the currents passing over it. It is ideal for long-term monitoring at a specific location. A buoy-mounted ADCP combines the advantages of mobility and ease of deployment, allowing for measurements in different areas.
The frequency of ADCP flow meter will be dependent on the water depth. For the water depths up to 70m, a 600kHz ADCP is quite appropriate because it gives highly resolved data in shallow waters. In the case of depths up to 110m, a 300kHz ADCP will be more appropriate. For deeper waters, such as those near 1000m, a 75kHz ADCP is recommended for accurate measurement over a large vertical range.
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.
Brand | model |
---|---|
Teledyne RDI | Ocean Surveyor ADCP , Pinnacle ADCP , Sentinel V ADCP , Workhorse II Monitor ADCP, Workhorse II Sentinel ADCP, Workhorse II Mariner ADCP, Workhorse Long Ranger ADCP, RiverPro , RiverRay , StreamPro , ChannelMaster etc. |
NORTEK | Eco, Signature VM Ocean, Signature ADCP, AWAC ADCP, Aquadopp Profiler etc. |
SonTek | SonTek-RS5, SonTek-M9, SonTek-SL, SonTek-IQ, etc. |
China Sonar | PandaADCP-DR-600K, PandaADCP-SC-300K, PandaADCP-DR-75K-PHASED, PandaADCP-DR-300K, PandaADCP-SC-600K etc. |
How to measure coastal currents of Qatar?