How to measure coastal currents of Alanya?

1. Introduction to Alanya

Alanya is a very captivating city situated on the southern coasts of Turkey and jewel on the Mediterranean Sea. Its geographical position is both strategic and idyllic, rendering it equally a favorite tourist destination and an important port. It lies within a bay, surrounded by the Taurus Mountains to the north, which not only create a breathtaking backdrop but also influence local weather patterns.

Its coastline is sandy, as can be seen at Cleopatra Beach, with steep cliffs elsewhere. Tourists like to come to the beaches for good locations for sunbathing, swimming, and other water sports. Rocky areas house different sea life since so many colorful fish, crustaceans, and mollusks reside in the various nooks and crannies.

Culturally, Alanya has a very rich heritage. It is influenced by the Romans, Byzantines, and Ottomans. Old Alanya Castle, on the hill above the city and sea, is one of the eye-witnesses of its ancient history. Since the local inhabitants traditionally lived along with the sea, its inhabitants are traditionally people of fishing profession, but its city cuisine does not lack all kinds of fresh seafood either. The annual festivals celebrate the marine traditions of this city and bind the locals and tourists together.

The coastal waters of Alanya are part of the greater marine ecosystem. In fact, the topography is really uneven; underwater valleys, underwater ridges, and reefs may be differentiated in this seabed. Those features make marine environments different reflecting a wide range of marine biodiversity.

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

Several elements come into play in determining the coastal currents around Alanya. Wind is a main driver. The Mediterranean Sea has a range of different wind patterns. During some months of the year, the meltemi-like winds, which are prevalent in this region, could push surface waters toward the shore. These onshore winds drive onshore currents that bring warmer waters from the open sea with nutrients. These nutrients stimulate the growth of phytoplankton, which form the base of the marine food chain.

Whereas, where winds blow offshore, the water moves offshore, thus creating an offshore current. The strength of these winds may fluctuate and the direction can change, too, causing fluctuation in the patterns of the coastal currents. Although relatively small compared with some other tidal forces around the world, those of the Mediterranean Sea nonetheless also help to influence the total movements of its water. The ebbs and flows of tides come in interaction with wind-driven currents. For example, at high tide, water might flow either in the opposite direction or speed from low tide, contributing to the current movement of a particular coastal system.

The other important factor is the bathymetry of the region. The topography of the sea bottom off Alanya is very irregular, with underwater valleys, ridges, and reefs. These may accelerate, decelerate, or change the direction of the currents. A narrow underwater channel can constrict the flow of water, increasing the current speed, while a large reef can act as a barrier, deflecting the current. River runoff from the surrounding rivers, though not as substantial as in some other regions, may still contribute freshwater to the coastal zone. This can alter the density of the seawater and thus produce density - driven currents that interact with the existing wind - and tide - driven currents.

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

Surface Drifting Buoy Method

The surface drifting buoy method is a simple way of observing the surface-level coastal currents. Small buoys equipped with GPS tracking devices are released into the water. Carried by the currents, the movement of the buoys is followed over time. By analyzing the buoy's trajectory, scientists can estimate the speed and direction of the surface currents. However, this method has its limitations. This makes them highly prone to the action of surface winds, which often shifts them considerably out of their path of travel. This can result in misleading readings of current velocity and direction. This is only a means to measure currents of the surface water and the movements of the lower -layer currents are not accounted for in this method.

Anchored Ship Method

A ship can be anchored as a fixed platform and current meters may be suspended at different levels. These meters can record the velocity and direction of the currents at each depth, providing a detailed vertical profile of the currents at a specific location. However, it is limited by the area it can cover. The data represents only the area immediately around the ship, and the presence of the ship itself can potentially disrupt the natural flow of the water.

Acoustic Doppler Current Profiler Method

In recent times, the Acoustic Doppler Current Profiler has become a rather coveted technique of measurement for coastal currents around Alanya. ADCPs use sound waves to measure the velocity of water at multiple depths simultaneously and can be deployed from ships, moored to the seabed, or attached to buoys. This flexibility allows for a more complete data collection. Since ADCPs are less affected by surface-level disturbances, such as wind, they provide more accurate measurements of the true current conditions. They can give a three-dimensional view of the current structure in detail, both for horizontal and vertical flow components.

4. How do ADCPs using the Doppler principle work?

The operation of ADCPs is based on the Doppler effect. The ADCP current meter sends out high-frequency sound waves into the water, which collide with the small particles in the water such as plankton, sediment, or tiny bubbles. These particles scatter the sound waves back towards the ADCP. The frequency of the scattered sound waves received by the ADCP is different from the frequency of the emitted waves. This frequency shift, which is known as the Doppler shift, is proportional to the velocity of the particles and hence the water relative to the ADCP.

Most ADCPs are multibeam transducers. By measuring the Doppler shift in each beam, the ADCP current profiler can calculate the components of water velocity in different directions. These are combined through vector addition to produce the three-dimensional velocity of the water. This would enable a detailed understanding of how the water is moving in all directions, which is crucial for the purpose of mapping coastal currents accurately.

5. What is needed to have quality measurement of the Alanya coastal currents?

Equipment Material Reliability

In Alanya's coastal waters, for high-quality measurements, the material of the casing of the ADCP is very important. It can be made from titanium alloy. The resistance of the titanium alloy to corrosion is outstanding, which is very vital because the equipment will always be exposed to the corrosive seawater. It can also resist long-time exposure to such a salty environment with no significant degradation to ensure longevity and reliability for the ADCP. In addition, the high strength-to-weight ratio signifies that the ADCP profiler will keep its structural integrity even in strong currents or rough seas.

Size, Weight, and Power Consumption

The ADCP flow meter shall be designed small in size and light in weight. Compact design-the instrument can be easily deployed in many various settings: on a small research vessel or buoy, for example. This small size minimizes the interaction with the flow field which is going to be measured. Another very important factor is its low power consumption that may enable it to work longer without replacing batteries or any other source of power coming from outside. This is considered crucial, particularly for long-term deployments in the coastal areas of Alanya.

Cost-effectiveness

To provide large-scale and comprehensive monitoring of Alanya's coastal currents, the ADCP meter should be cost-effective. This way, more research institutions, environmental monitoring groups, and local initiatives will have the ability to purchase equipment. Huge-scale data collection would therefore be possible, which is of paramount importance in view of a better understanding of the complex dynamics of coastal currents.

6. How to Select the Right Equipment for Current Measurement?

Depending on the Purpose of Use

• Shipborne ADCP: This type is mounted on a moving ship and is ideal for conducting large-scale surveys of coastal currents. For example, during the movement of the ship down the coast, the shipboard ADCP would measure the current continuously to achieve a broad view of the larger-scale current patterns over a very large area, which is advantageous in preliminary studies or studies wherein changes in large geographical areas should be observed.
• Bottom-Mounted ADCP: These are placed on the seabed; bottom-mounted ADCPs are used for long-term, fixed-point monitoring. They can provide continuous data on the currents at a specific depth and location. This is valuable to understand the local hydrodynamics, such as how the currents behave in a particular bay or near a specific underwater feature.
• Buoyant ADCP: Buoyant ADCPs are attached to a floating buoy and can move about with the surface currents. They are well-suited for monitoring the surface and near-surface current patterns. They also enable the study of water mass movements over time, which is another important factor in observing transports of nutrients, pollutants, or marine organisms.

Based on Water Depth

• For water depths within 70m, a 600kHz ADCP is quite adequate. With a higher frequency, the sound waves can go to greater detail for shallower waters. This provides high-resolution data on the structure of the current, thereby allowing the detection of small-scale changes in the currents.
• For water depth of about 110m, the 300kHz ADCP will be adequate. This provides a middle of the range resolution and measurement and has deeper penetrations in the water column relative to the ADCP 600kHz but yet will not offer much accuracy to mid-depths waters along coastal areas.
• In deeper waters of up to 1000m, a 75kHz ADCP would be recommended. In such water, the low frequency of the sound waves is able to travel deeper but usually with a coarser resolution than higher-frequency ADCPs. Hence, this model will be good enough to measure currents in deeper areas of the Mediterranean Sea off Alanya.

A few well-recognized ADCP brands in the market are Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective yet high-quality option, the China Sonar PandaADCP is a great choice. Made of all-titanium alloy, it offers excellent durability and performance at an affordable price. It is an economic-class ADCP that provides great value for money. You can find more information about it on their official website: (https://china-sonar.com/).

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