How do we measure Cartagena's coastal currents?

1. Where is Cartagena?

Cartagena, located on the north coast of Colombia, is a historic and living port city. Located on the Caribbean Sea, the city serves as a significant gateway between Europe and the Americas. The geographical position of the city, which lies overlooking the Gulf of Morrosquillo, is scenic with clear waters and a prosperous coastal ecosystem.

The Gulf of Morrosquillo, which borders Cartagena, is a large body of water that plays a significant role in the marine ecosystem of the region. The gulf has a diverse population of marine life, from the colorful tropical fish to the magnificent sea turtles. The warm waters of the gulf are suitable for a healthy coral reef system, which not only serves as a haven for the marine animals but also one of the favorite tourist spots among snorkeling and scuba diving fans.

Cartagena itself has a history of over 500 years. Cartagena was founded in 1533 by Spanish conquistadors and quickly became an important center for colonization and trade. Cartagena's still preserved colonial architecture in the shape of its great walls, fortresses, and cobblestone roads is all a testimony of its past. Cartagena's economy nowadays is driven by tourism, shipping, and fishing together. The city's ports receive a significant portion of Colombia's foreign trade, and its beaches and historic centers receive millions of tourists annually.

2. What are the coastal currents near Cartagena?

Nearshore currents off Cartagena are governed by a complex interaction of a number of factors. Tides, although quite small in the Caribbean Sea compared to other seas, still have a great impact on regional hydrodynamics. The diurnal and semi - diurnal tidal regimes cause small water - level fluctuations, which can lead to the development of weak tidal currents.

Regional prevailing winds, most notably the northeast trade winds, have a strong control over the coastal currents along the region. The winds push surface waters, which overall results in westward flow along the northern coast of Colombia. The Caribbean Current, a huge ocean current within the region, also has long - reaching effects on the regional coastal currents. It flows westward along the north coast of South America, in contact with the wind - driven tides and currents to create a complex pattern of water circulation.

Oceanic eddies, formed by the mixing of different water masses, also contribute to the complexity of coastal currents off Cartagena. These eddies create localized direction and velocity changes of the currents, making it hard to predict the specific flow patterns. The shape of the seafloor bathymetry and coastline also influence the coastal currents. Underwater reefs, shoals, and channels either direct or scatter the motion of currents.

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

Surface Drifting Buoy Method

Surface drifting buoy method is another traditional method for observing coastal surface currents. Researchers release buoys into water and note their drift over a period of time. They infer the direction and speed of surface currents from where the buoys are seen to be lying over time. However, this is limited to the surface level of the water column and is highly susceptible to wind disturbance. The wind can cause the buoys in a way that does not indicate the direction of movement of the current beneath, thus giving inaccurate readings.

Moored Ship Method

The moored ship method employs a moored ship as a platform for current measurement. Equipment is dropped off the vessel to measure the water current at varying depths. Despite the fact that the method can produce accurate vertical profiles of the currents, it is plagued with a variety of shortcomings. Spatial coverage is confined to around the moored vessel, and the ship can disrupt the natural flow of water, affecting the measurements. Also, long-term docking of a ship is logistically unsuitable and costly.

Acoustic Doppler Current Profiler (ADCP) Method

ADCP meter has evolved into a more advanced and efficient tool to quantify coastal currents. ADCP can quantify currents in water over a broad vertical range, providing accurate information about the velocity structure of the water column. ADCPs can be installed on various platforms, including ships, buoys, and the seafloor. Ship-mounted ADCPs are able to take measurements continuously while the ship travels, surveying a great area in a short period of time. Bottom-mounted ADCPs are able to make long-term, fixed-point measurements so that researchers are able to investigate the long-term trends in the coastal currents.

4. How do ADCPs based on the Doppler principle function?

ADCPs apply the Doppler principle. They emit acoustic pulses into the water. These pulses bounce off suspended waterborne particles, like sediment, plankton, or bubbles. When the water is in motion, the frequency of the backscattered pulses is changed. By detecting this frequency change, the ADCP current profiler can calculate the speed of the water relative to the instrument.

Most ADCPs have more than a single transducer beam, typically four or more, at various angles. Such a multi - beam configuration enables the measurement of three - dimensional water velocity. The ADCP can create a high - resolution picture of the current velocity at many depths in the water column by combining the signals of such beams. The data collected with the ADCP may either be analyzed in real-time or stored and utilized later for analysis, providing valuable information on the dynamics of the coastal currents.

5. What is needed to measure Cartagena coastal currents of high quality?

To perform color-quality measurement of coastal currents in Cartagena, the measurement device should possess a number of key characteristics. It should be manufactured with reliable material, compact size, light weight, low power consumption, and affordable costs. All these characteristics enable color-quality measurement using a large number of instruments so that there can be significant color-quality spatial coverage.

Tidepiles of titanium alloy casings are highly recommended. Titanium alloy is well known for its high resistance to corrosion, which is a major necessity for long - term exposure in the harsh marine environment. It can withstand the corrosive effect of saltwater and thus shield the internal components of the ADCP from destruction. Additionally, titanium alloy is light in weight and strong, offering strength and mobility to the instrument. This combination of properties allows accurate and long-term measurements of the coastal currents off Cartagena.

6. How to Choose the proper equipment for current measurement?

Selection According to Usage

The ADCP is chosen according to its usage. In ship-borne measurements, ship-mounted ADCPs are the best choice. They can provide in - real-time data as the ship moves along the water surface, clearing a huge extent in a correspondingly short period of time. Bottom - mounted ADCPs, however, are better suited for fixed-point long - term observation. They will provide continuous records over a considerable duration, wherein scientists can take a glimpse at the long - term trends prevailing in the coast currents. Floating ADCPs are useful to investigate the motion of water masses in large regions, providing valuable input on the large - scale circulation patterns.

Based on Depth Selection

The ADCP frequency must also be taken into consideration based on water depth. 600kHz ADCPs would be appropriate for water depths less than 70m. They are capable of measuring high-resolution values in shallow waters. For water depth up to 110m, 300kHz ADCPs are appropriate. For deeper waters, up to 1000m, 75kHz ADCPs are appropriate.

There are various popular ADCP brands available in the market, including Teledyne RDI, Nortek, and Sontek. For people who want affordable options, the ADCP supplier China Sonar'sPandaADCP is really worth recommending. It is made of pure titanium alloy and provides great performance without costing a fortune. It is perfect for users who want to save money while still needing good ADCPs for measuring coastal currents. Additional information regarding their business activities is accessible on their website: https://china-sonar.com/.

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