How can we measure coastal currents in the case of Elche?

1. Where is Elche

Elche is a city located in the province of Alicante and part of the Valencian Community of Spain. It lies inland, not far from the Mediterranean Sea, boasts a varied landscape of coastal beauty, and is full of inland heritage. The city boasts palm groves that are a UNESCO World Heritage Site, adding this particular touch to the scenery of the area.

The littoral around Elche presents sandy beaches and a seabed with quite a gentle slope. In the Mediterranean waters, there is a variety of marine life, including different species of fish, mollusks, and seaweeds. The climate is typically Mediterranean, with warm, dry summers and mild winters. This climatic feature influences not only the local flora, but it is also connected to temperature and salinity features of coastal waters, having a great influence on the currents of the coasts.

As for the human impact, the most influential industries are those connected with fishing and tourism. The closeness of the city to the sea attracts lots of beachgoers and people who like sports connected with water.

2. What is the situation of the coastal currents in the region of Elche?

The coastal currents of Elche depend on many factors. The general characteristics of the circulation of the Mediterranean Sea play a major role. There is a well-known anti-clockwise circulation in the Western Mediterranean, which affects the movement of water in the area. The tides also have their share, though the tidal range is rather insignificant in the Mediterranean. It might cause some tidal currents with the effects of back -and- forward motion of the water, although weaker compared to areas with large tidal ranges.

The local winds are not to be excluded either. The general circulation of prevailing winds, that is, the easterly and the westerly winds, will drive the surface currents. Besides this, more intense changes in the surface current happen because of a summer month's sea breeze. Changes in the directions of currents result from underwater topography, or bottom ridges and valleys. In any case, contributions coming from local rivers and rivulets change coastal waters' salinity and densities, thus affect current patterns at least to some critical degree.

3. Como medir caudal costa Elche?

Surface Drift Buoy Method: Surface drift buoys are deployed on the water surface. These buoys are designed to move with the surface currents. Their positions can be tracked using GPS or other satellite-based tracking systems. From the movement of these buoys over time, the direction and speed of the surface currents can be determined. This is the traditional method that, however, can give information only about the surface layer and cannot fully represent currents in different layers.

Anchored Ship Method: It is a technique in which current can be measured from an anchored ship. Instruments necessary for the measurements of water flow around it are installed on the ship. It allows further accuracy in a certain point; however, its usage is confined within the vicinity around the anchored ship, and sometimes the ship obstructs the very flow of the water it measures.

With its high power and efficiency, Acoustic Doppler Current Profiler(ADCP) is more advanced in measuring coastal currents. It can measure simultaneous water velocity at more depths by broadcasting sound waves. The ADCP will emit an acoustic pulse and analyze the Doppler-shifted reflections to get a detailed profile of the current right from the surface down to a certain depth. This allows a deeper understanding of the coastal currents in the vicinity of Elche compared to the other approaches.

4. How do ADCPs using the Doppler principle work?

The ADCP depends on the Doppler effect. It sends acoustic pulses into the water. When these sonic waves reach any other moving water particles, due to the Doppler effect, the waves' frequency changes relatively in accordance with the flow velocity. The relative frequency shift is proportional to the velocity of the water particle.

Each ADCP has several transducers, which allows the interrogations to be received and sent over different directions. The frequency shifts in different directions allow the ADCP to compute the velocity components of the water in horizontal and vertical directions. Since the acoustic pulses are sent at regular periods and at different depths, a profile can be constructed from the current velocities throughout the column of water. This provides information on flow patterns, including the direction and speed, as well as any vertical shears that might exist in the currents.

5. What is required to achieve high - quality measurement of Elche coastal currents?

The measuring instruments used in the measurement of coastal currents near Elche should be made from materials that are reliable. Since seawater is corrosive and the general marine environment can sometimes be harsh, resistance to saltwater corrosion, changes in pressure, and eventual impacts add to the important attributes of materials. A small size and lightweight will go a long way in ensuring ease of deployment either on a ship, a buoy, or at the seabed. Low power consumption is necessary for operation over long periods without frequent changes in batteries or disruption of power sources. Cost-effectiveness is also a factor to be considered in order to enable large-scale measurements.

In the casings of ADCPs, titanium alloy is a very good material. The corrosion resistance of the titanium alloy is excellent, something very important to resist the corrosive seawater near Elche. Besides, it has a high strength-to-weight ratio, meaning it can provide the necessary strength to protect the internal components while keeping the overall weight of the device relatively low, thus facilitating easy handling and installation.

6. Selection of Appropriate Equipment for Current Measurement?

Based on Deployment Method

Ship-borne ADCP: This would be proper if one wants to measure the currents either while the ship is in motion at any coast or stays at any place. One will have all the flexibility regarding coverage of area and can provide continuous data when the ship changes the position.

Bottom-mounted ADCP: Most suitable for fixed-point measurements on the seabed. It is a means to collect long-term data of current conditions at a given site accurately and could form the basis of the local current patterns.

Buoy-mounted ADCP: Attached to a buoy floating on the water surface, it can measure currents in the upper layers and transmit data wirelessly. It is convenient for remote monitoring that can cover a large area depending on the buoy movement.

Based on the Frequency

Different frequencies suit different water depths. For example, a 600 kHz ADCP is ideal in water depths up to a maximum of 70 meters. Similarly, a 300 kHz ADCP will cater for up to 110 meters of depth, while a 75 kHz ADCP can cater for much deeper waters up to a depth of 1000 meters. This will ultimately allow you to choose the most ideal ADCP depending on the actual conditions of the water depth in the Elche coastal area.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also a great option. It is made of all - titanium alloy material, ensuring durability and offering an excellent cost - performance ratio. You can visit their website at https://china-sonar.com/ for more information.

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