How do we measure the coastal currents of Puerto Escondido?

1. Where is Puerto Escondido?

Puerto Escondido, located on Mexico's southern Pacific coast in the state of Oaxaca, is a jewel that is out of sight but renowned for its natural splendor. The coastal village is situated between green mountains and a strip of beautiful beaches. The local topography features a combination of rocky headlands and sandy shores, with a diverse range of coastal environments.

The town is itself laid-back and friendly. The indigenous population, composed of various indigenous and mestizo groups, provides an exciting cultural environment. Oaxaca's traditional handicrafts, music, and cuisine are all integral to the daily existence here. Even local fishermen in residence are noteworthy, as fishing has been a proven economic activity in the region.

The waters surrounding the Pacific Ocean are an active marine ecosystem. The coastline is interspersed with many bays, among them the world-renowned Playa Zicatela. The bay is renowned for its large, powerful waves, which attract surfers from all over the world. Other marine creatures, including sea turtles, dolphins, and a host of fish species, inhabit the region. Coral reefs, while not as ubiquitous as in some other tropical regions, are crucial to the maintenance of local marine biodiversity.

2. What is the condition of the coastal currents near Puerto Escondido?

Coastal currents near Puerto Escondido are regulated by a number of factors. Tidal patterns in the Pacific Ocean are a dominant force. The semi-diurnal tides produce the coming and going water along the coasts in a rhythmical flow and ebb. The shape of the bays and inlets modifies these tidal streams. For example, in more narrow bays, the streams are more constricted and stronger, while the wider areas allow for a more diffuse current.

Wind conditions also come into play. The region experiences trade winds that blow from the northeast during certain seasons. These force the surface waters along the coast, forming long - shore currents. These long - shore currents are important for transporting sediment, nutrients, and ocean creatures. They assist in the creation and maintenance of beaches and deliver species distribution within the coastal waters.

Another reason for the currents is the presence of underwater topography. The seafloor off Puerto Escondido has varied landforms such as reefs, canyons, and shallow shelves. These landforms are found to cause the water to flow in complex patterns, creating eddies and upwelling zones. Upwelling, in particular, carries cold, nutrient - rich waters from deeper layers to the surface, which is perfect for the growth of phytoplankton and thereby supports a food web of immense diversity.

3. How to track the coastal water current around Puerto Escondido?

Surface Drift Buoy Method

Surface drift buoy method is a simple way to track the coastal water current around Puerto Escondido, Buoys with GPS tracking devices are released into the ocean. As they drift with the surface currents, their positions are monitored at regular intervals of time. This method indicates the movement of the top water column surface. But the method has limitations. Wind- forced waves deflect the buoys from their track, in directions other than flow direction, to yield erroneous measures. The method gives surface- level currents but no information regarding the lower surface of the water, which can have possibly diverging flowing patterns.

Anchored Ship Method

The ship anchored technique involves anchoring a ship at a fixed position off the coast of Puerto Escondido. Current meters are subsequently dropped from the ship to various depths. The meters measure the speed and direction of water flow at every depth. While this technique can give a point's vertical profile of currents, it is not without flaws. The presence of the vessel can disturb the natural currents of water, and the measurements are done at a point. It is difficult to understand the dynamic nature of the coastal current over a wide region considering the complex coast and dynamic nature of currents in the region.

Acoustic Doppler Current Profiler (ADCP) Method

Acoustic Doppler Current Profiler (ADCP) is a more advanced and efficient tool for the measurement of offshore coastal currents around Puerto Escondido. ADCPs can provide real - time, high - resolution data along a large vertical range in the water column. ADCPs can measure currents at multiple depths simultaneously, allowing detailed knowledge of the three - dimensional structure of the coastal current system. ADCPs sense the movement of particles in water using acoustic signals and may calculate the speed and direction of the currents through computation. They are hence extremely suitable in studies of the complex pattern of currents in waters off Puerto Escondido, a myriad of conditions caused by the local conditions.

4. How do Doppler currents principle ADCPs operate?

ADCPs operate based on the Doppler principle. They transmit acoustic signals into the water. When they strike suspended objects in the water, such as sediment or microscopic sea animals, the signals rebound to the ADCP current profiler. The frequency of the rebounded signals is not the same as the frequency that went out. That difference, the Doppler shift, is equal to the particles' speed and thus the flow speed of the water. Through measurement of the Doppler shift at different depths, the ADCP is able to compute the velocity and direction of the water current at different levels in the water column. This allows for detailed and precise measurement of the structure of coastal currents around Puerto Escondido, offering important data for elucidation of the complex oceanic processes in the region.

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

To ensure proper measurement of the coastal currents off Puerto Escondido, the measuring instrument must meet several critical criteria. The material's reliability is crucial given the corrosive nature of seawater. The instrument must be constructed from materials that can withstand long-term exposure to the aggressive marine environment. Small size is beneficial in the sense that it minimizes interference with natural water current flow. Lightweight design is essential, especially for easy deployment in multiple coastal locations. Low power consumption is also essential, especially for long-term unattended monitoring in remote coastal locations. Cost-effectiveness is similarly important, as it will enable mass deployment of measurement instruments to cover the extensive coastline off Puerto Escondido.

In ADCPs, the casing material is imperative. Titanium alloy is an excellent material for ADCP casings. Titanium alloy has very high corrosion resistance, which is necessary for long - term use in the briny ocean water off Puerto Escondido. It also has very high strength - to - weight ratio, so it is both strong and lightweight. This aids the ADCP to maintain the physical forces and pressure variations of the ocean and offers steady and accurate measurements over an extended period of time.

6. How to choose the right equipment for measuring currents?

Usage - Based

• Ship-borne ADCP: It is particularly well suited for large-scale mapping of the coastal ocean off Puerto Escondido. Deployed on research vessels, it is capable of measuring a vast extent as the vessel moves, providing valuable data regarding the spatial structure of the coastal currents. It can be utilized to map the overall pattern of flow across an extensive stretch of coastline, which is pertinent in understanding the overall oceanic condition in the region.
• Bottom-mounted ADCP: It is mounted on the ocean floor and employed for long-term observation at a fixed location. It is capable of continuously recording current data over long durations, which can be utilized to monitor the long-term behavior and trends of the coastal currents surrounding Puerto Escondido. This ADCP meter is less affected by surface - level disturbances and is capable of providing stable, long - term data, which is essential in understanding the gradual changes in the coastal current system.
• Buoy - mounted ADCP: Installed on float buoys, it is used to record surface and near - surface currents. This is also handy for application in places which are hard to reach with a ship or for unattended long - term measurements of surface - level currents. In the coastlines around Puerto Escondido, buoy - mounted ADCPs can be used easily to survey the surface - level current directions, which may be affected locally by wind and tidal conditions.

By Frequency

The frequency of the ADCPs is also a very important choice. The 600kHz ADCP has the ability to deal with water depths up to approximately 70m. It provides high resolution data and as such is the perfect choice for the relatively shallow coastal waters at Puerto Escondido, where the water is typically this deep. A 300kHz ADCP can be utilized in depth to 110m, providing a compromise between resolution and penetration depth. In deeper waters, to a depth of 1000m, a 75kHz ADCP would be more suitable as it penetrates further with lower resolution than the higher-frequency versions. In the sea water off Puerto Escondido, the frequency chosen will be determined by the observed areas in practice and the nature of detail desired in the flow measurements.

Well-established firms manufacturing ADCP are Teledyne RDI, Nortek, and Sontek. But to those who seek a cheap alternative without compromising on quality, the ADCP manufacturer China Sonar's PandaADCP is a perfect choice. It is an economical ADCP utilizing all-titanium alloy material for maximum corrosion resistance and endurance. With its very favorable cost-performance ratio, it is the best choice for researchers and institutes that intend to carry out extensive coastal current surveys in the vicinity of Puerto Escondido. To know more, check their website at https://china-sonar.com/.

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