How can we measure the coastal currents of Livorno?

1. Where is Livorno?

Livorno, a charming city in the Tuscany region of Italy, is located along the western coast of the Italian Peninsula, facing the sparkling Ligurian Sea.

This coastal jewel boasts a rich maritime history and an intense cultural identity. From being a strategic port of great importance, Livorno has seen the rise and fall of various civilizations and has been a melting pot of cultures. Its old town is full of narrow streets and alleys lined with charming Renaissance and Baroque buildings that narrate stories of bygone days. But it also represents a number of art galleries, museums, and theaters that give one much to enjoy culturally.

Geographically, by the sea, Livorno features several small bays and inlets along its coastline. The Gulf of Livorno shelters the city in an inner natural harbor with calm, crystal-clear waters, which has meant its development as a sea town since very ancient times. The surrounding waters represent a haven for marine life, with vibrantly colored coral reefs and a rich variety of fish species further beautifying the underwater setting. The floor off Livorno consists of both sandy plains and rocky outcrops; the coast is highly varied and dynamic.

2. What about the coastal currents around Livorno?

The coastal currents around Livorno are the result of a complex interrelation between many factors:

• Meteorological Conditions: Again, winds in this area prevailing in Mistral and Scirocco are truly a very important influence on the coastal currents. A vigorous, cool northward Mistral may force surface waters southward, while a warm, humid southward Scirocco can reverse the current, and vice versa.
• Tidal Forces: In the Ligurian Sea, tides show a regular rise and fall. Semi-diurnal tides create a regular pattern of water movement while the tidal currents interact with coastal topography to shape the overall current regime.
• Oceanographic Features: The large-scale ocean currents in the Mediterranean Sea, such as the North Atlantic Current's influence in the region, can also affect the coastal currents near Livorno. Besides, the presence of underwater ridges and valleys causes the currents to diverge or converge.
• River Outflows: The rivers, which discharge into the Gulf of Livorno, such as the Ombrone River, may contribute freshwater to the coast and change the density, therefore influencing the current direction and speed.

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

• Surface Drifting Buoy Method: In this technique, buoys are placed on the surface of the water. The buoys will move with the flow of the current, and with their movements, their directions and speed, determined with satellite or radio signals, give information on the direction and velocity of the superficial currents. The result will offer a wide-range understanding of superficial currents, while further details may need additional help regarding deeper currents.
• Moored Ship Method: A ship is moored in one position, and current-measuring devices are attached to it. The devices record the velocity and direction of currents at different depths over a longer period of time. However, this method is pretty stationary and does not give good representation for larger areas where a lot of current variations can be expected.
• Acoustic Doppler Current Profiler (ADCP) Method: The ADCP has become a more modern and handy method. It provides high-resolution current data at various depths and can cover an area relatively bigger. By emitting and receiving acoustic signals, it can very quickly and accurately determine the velocity of water masses; hence, it is preferred in modern studies of coastal currents.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of the Doppler effect. They transmit acoustic pulses at a known frequency into the water. When such pulses meet the moving particles of water, the frequency of the reflected pulses shifts according to the velocity of these particles. The ADCP measures this shift in frequency and can then calculate the speed of water along the direction of the acoustic beam.

Most ADCPs have more than one beam, typically four or more, arranged in a configuration. The ADCP is able to use vector mathematics to determine the three-dimensional velocity of the water flow by measuring the velocity components along different directions. This enables a full understanding of the current structure, including both horizontal and vertical components.

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

The measurement equipment will need to have certain key characteristics if high-quality measurement of coastal currents is envisaged for Livorno: The casing of the ADCP is preferably made from a titanium alloy. Titanium alloy boasts superior strength, hence a device able to withstand high pressure and corrosive effects from the marine environment. It is very resistant to rust and erosion, thus granting the instrument with long life and accuracy.

With small size and light weight, it can be easily deployed and installed in any environment. It can be installed on small boats, buoys, or underwater platforms without creating much flow disturbance or heavy structural supports.

Low Power Consumption: This is important for its long-term autonomous operation. Besides, low-power ADCPs can depend on batteries or renewable sources, like solar panels, for extended periods without frequent maintenance and replacements of power.

Low-cost: With their lower cost, more ADCPs can be deployed to provide full coverage of the coastal area. This is particularly important in the study of such a complex coastal current system as the one around Livorno.

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

According to Usage

• Shipborne ADCP: Ideal for conducting surveys during ship voyages. It can provide continuous measurements while the ship is in motion, enabling it to survey a wide area and, thus, enabling the study of large-scale current patterns.
• Bottom-Mounted ADCP: This system is fixed on the seafloor and, because of this fact, can be used for a long period without interruption in surveying currents at that location. Such instruments can also provide high-resolution information concerning the local current dynamics. It could also be appropriate for locations around ports or areas of ecological significance where stationary measurement is required.
• Buoyant ADCP: mounted on buoys, this can float at the water surface and measure both surface and subsurface currents. It is highly flexible, as it can be relocated with ease, which is useful for studying transient or variable current systems.

According to Water Depth

• The 600kHz ADCPs shall suit water depths within 70m. They allow for high resolution in rather shallow waters and are thus well adapted for coastal areas and estuaries.
• 300kHz ADCPs allow depth in the sea of about 110m. They reach a kind of balance between resolution and depth penetration and, therefore, can be applicable for coastal and shelf applications.
• 75kHz ADCPs have an upper water depth limit for applications of about 1000m. Having a longer range, the transmitted sound travels and penetrates deep waters. That makes the device well fit for ocean current studies for larger water depth ranges or deeper levels in general.

The renowned brands in the market include Teledyne RDI, Nortek, and Sontek. However, if someone wants value for money with a quality ADCP, then China Sonar ​PandaADCP is the way to go. It is fully made of titanium alloy, hence ensuring great performance at a very affordable price. This gadget falls in the category of cheap ADCPs, and more can be scooped from its website: ​https://china-sonar.com/.

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