How can we measure the coastal currents of Punta Cana?

1. Where is Punta Cana?

Punta Cana is situated on the easternmost coast of the Dominican Republic, a country that shares the island of Hispaniola with Haiti. It is a tropical haven, famous for its serene beaches and crystal-clear waters. The Caribbean Sea borders it on all sides, which not only makes for a beautiful backdrop but also influences the local environment in various ways.

The culture that exists in the region is alive and grew from the indigenous Taíno, African colonizers, and European colonizers. The locals are amiable and kind, and their history is lived out in music such as merengue and bachata, and vibrant festivals. Economically, tourism sustains Punta Cana. The area is home to many high-end resorts that receive millions of tourists annually who flock to the area to enjoy the stunning beaches, water activities, and lively nightlife.

The sea waters off Punta Cana harbor a variety of marine ecosystems. Coral reefs are plentiful and support a large variety of fish and other sea creatures. The coast has long sandy beaches with the occasional rocky outcrop. These physical characteristics, along with the Caribbean Sea, make the hydrographic conditions around the coastline very distinctive, which has a profound effect on the coastal currents.

2. What is the situation of the coastal currents near Punta Cana?

The nearshore currents along Punta Cana are influenced by several factors. The tidal forces also play their role, which the Caribbean Sea has semi-diurnal tides. The semi-diurnal tides cause inflow and outflow of water into the coast, affecting both the surface flow and subsurface flow of water. The intensity and direction of the tidal current may vary as a result of local topography, such as the geometry of bays and the narrowness of channels.

Wind regimes are another chief determinant. Steadily blowing trade winds, coming from the northeast, push surface waters. The winds are able to drive water onshore, forming onshore currents, or alongshore, forming long-shore currents. From June to November, when hurricane season is in progress, strong storms can have a profound effect on the current regime. Hurricanes can generate large - scale water movements, including storm surges that can temporarily alter the normal coastal current regime.

The topography of the coastline, above as well as beneath the water level, also controls the currents. The curvature and inlets that characterize the Caribbean coastline determine where the water must go. Natural barriers below water, the coral reefs, cause wave energy dissipation and changed speed and directions of the current. Interaction with the major current of the region, the Caribbean Current, along with local coast features, only adds to this complexity near Punta Cana.

3. How to monitor the coastal water flow of Punta Cana?

Surface Drift Buoy Method

Surface drift buoys are an easy yet efficient means of monitoring the coastal water flow off Punta Cana. The buoys have GPS tracking instruments and are deployed in the coastal waters. While being swept along by surface currents, they are tracked at suitable intervals. This technique yields useful information concerning the flow of the top layer of the water column. It has its disadvantages, though. The buoys may be deflected from the true water - flow path by wind - driven waves, and the technique only records surface - level currents, which give a limited picture of the entire current structure.

Anchored Ship Method

The anchored ship technique is that of mooring the ship to a point in the coast at Punta Cana. A current meter then has to be dropped from this ship at multiple levels. In these meters, it records every level's velocity and direction in flow. However, this technique provides a one-point vertical profile. It disadvantages itself. Furthermore, the presence of the ship also disrupts the normal flow of water, and the measurements are only at one point, hence making it difficult to have an entire view of the patterns of the current around the coastal area.

Method ADCP

The ADCP current meter is a complex and effective tool, which can be used to measure the coastal currents near Punta Cana. It provides real-time and high-resolution measurements of the three-dimensional structure that cover an entire vertical range inside the water column. Simultaneously, a variety of measuring depths can obtain the currents inside it, creating a very intricate understanding of current patterns in relation to the coastline system. Because of this capacity, ADCPs are in quite good position regarding investigating the intriguing patterns of flows within the off-shore of Punta Cana waters.

4. How do ADCPs employing the Doppler principle function?

ADCPs function on the basis of the Doppler principle. They send out acoustic signals into the water. When the signals hit suspended particles in the water, e.g., sediment or small marine animals, the signals are deflected back towards the ADCP profiler. The frequency of the deflected signals is different from the initial emitted frequency. This difference, termed the Doppler shift, varies directly as the velocity of the particles, and therefore as the velocity of water flow. Measurement in several layers is sufficient to determine the speed and direction of water flow at a variety of points within the column of water and hence enables measurement of the total and accurate description of the current structure at coastal points near Punta Cana.

5. What does the quality of measurements of coastal currents of Punta Cana need?

High-quality measurement of coastal currents at Punta Cana can only be assured with meeting of few specific conditions which measurement equipment is required to be subjected to. First and foremost, since water at Caribbean regions is aggressive corrosionally, there must be proper reliability in terms of materials that could survive this severe marine exposure. Small size is advantageous because it reduces interference with natural water flow. Lightweight construction is significant, particularly for simple deployment at various coastal sites. Low power consumption is necessary, especially for long - term, unmanned monitoring in distant areas. Cost-effectiveness is also a consideration since it facilitates large-scale deployment of measuring devices.

For ADCPs, the casing material selection is very critical. Titanium alloy is an excellent choice for ADCP meter casings. Titanium alloy has excellent corrosion resistance, which is important for long-term use in the salty waters around Punta Cana. It also has a high strength-to-weight ratio, which makes it lightweight and durable. This permits the ADCP flow meter to endure the physical pressures and pressure fluctuations that are present in the ocean, providing sound and precise readings for a long duration of time.

6. How to Select the right equipment for current measurement?

According to Usage

• Ship-borne ADCP: This is the most suitable ADCP for large-scale surveys of the coastal waters around Punta Cana. Mounted on research vessels, it can cover a wide area as the ship moves, providing valuable data on the spatial distribution of coastal currents. It is useful for mapping out the general current patterns over a large expanse of the coastline.
• Bottom-mounted ADCP: Installed on the sea floor, it is used for long-term measurement at a fixed location. It is capable of recording current data continuously over long periods, which is useful in investigating the long-term trend and behavior of coastal currents in the vicinity of Punta Cana. It is less disturbed by surface-level disturbances and can give stable long-term data.
• Buoy-mounted ADCP: Suspended from floating buoys, it is employed to determine surface and near-surface currents. It is convenient for deployment in places where a ship cannot access or where surface-level currents need to be monitored unattended and long-term.

Based on Frequency

The selection of frequency for ADCPs is a crucial consideration. A 600kHz ADCP would be appropriate up to a depth of about 70m, and its data resolution would make it a very good tool for the relatively shallow coastal waters off Punta Cana. For depths up to 110m, a 300kHz ADCP is well balanced between the resolution of data and penetration to depth. For deeper waters, up to 1000m, a 75kHz ADCP is more appropriate as it can penetrate to greater depths but with a lower resolution compared to the higher-frequency models.

There are several well-known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. Still, for cost-effective solutions without quality compromise, The PandaADCP, a product of the ADCP manufacturer China Sonar, is an excellent choice. China Sonar Panda is an economic ADCP based on all-titanium alloy material, which has great corrosion resistance and durability. With its incredible cost-performance ratio, it is a suitable choice for researchers and institutions with plans to make large-scale coastal current measurements near Punta Cana. For more details, go to their website at https://china-sonar.com/.

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