How do we measure coastal currents of Port Mourant?

1. Where is Port Mourant?

Port Mourant, situated on Guyana's eastern shore, is along the Atlantic Ocean. It is near the mouth of the Corentyne River, a key waterway in the region. The Corentyne River forms a natural border between Suriname and Guyana, and its mouth to the Atlantic Ocean significantly affects the nearby coastal environment.

Geologically, the Port Mourant area is characterized by flat, low-lying plains. The coastline consists of a combination of sandy beaches, mudflats, and vast expanses of mangrove forests. Not only are the mangroves ecologically important, but they also provide a natural defense against coastal erosion. They are a habitat to a wide variety of marine and terrestrial fauna, including numerous species of fish, birds, and crustaceans.

Port Mourant has a robust and diverse history. The original inhabitants of the area were the indigenous people, and their heritage still finds expression in local custom, art, and folklore. European colonists, especially the Dutch and the British, settled there in the 17th and 18th centuries. They brought in sugar plantations, which for some decades formed the backbone of the local economy. The cultural architecture and practices of Port Mourant still signify this colonial past.

Currently, Port Mourant's economy is fueled by a mix of small-scale industries, fishing, and agriculture. Agriculture, especially the cultivation of sugarcane, remains a major sector. The fishing industry is also thriving, with local fishermen in the surrounding waters catching various species of fish.

2. What is the state of coastal currents off Port Mourant?

The coastal currents off Port Mourant are characterized by a multivariate interaction that is intricate in nature. One of the broad influences is Corentyne River discharge. The large amount of freshwater flowing into the Atlantic Ocean forms a plume. The plume controls salinity and density of the waters along the coast, and a coastal current that is unlike the rest of the oceanic current is produced. The size and height of the plume may vary regarding the amount of flow of the river depending on seasonal rainfalls in the Corentyne River basin.

The Atlantic Ocean tides contribute significantly to them. Repeated variations of the water level by the semi-diurnal tidal cycle cause typical variations in water levels. More tidal currents during spring tides occur as a result of increased gravitational forces from the sun and moon. These tidal currents, in combination with river-plume current, alter coastal-water general movements.

Local prevailing winds, mostly the northeasterly trade winds, push surface water to the west. The wind-driven current combines with the river-plume current and tidal currents. The combination creates a complex pattern of water movement. Bathymetry of the seafloor, the changing depths, and submerged landforms such as sandbars, channels, and reefs, introduce complexity into the coastal currents. These submerged formations can either guide or discontinue the present current flow of the currents, developing eddies and other complex flow regimes.

3. How to track the Port Mourant coastal water flow?

Surface Drifting Buoy Method

Surface drifting buoy method is a vintage method of tracking coastal water flow. Researchers buoy up floating markers with tracking units in the sea. By seeing the trajectory of the buoys over time, they can determine the direction and strength of the surface currents. The method, however, has limitations. It can only inform them regarding the surface layer of the water column, and the buoys are highly susceptible to being affected by wind. Wind can cause the buoys to follow a trajectory other than the actual trajectory of the currents beneath.

Moored Ship Method

The moored ship method is a technique where a fixed ship is used as a platform to measure currents. Instruments are lowered from the ship to measure the water current at various depths. While the method can provide detailed vertical profiles of the currents, it also has some drawbacks. Geographic coverage is limited to the surrounding area of the moored ship, and the ship's presence can disrupt the natural flow of water, affecting the accuracy of the measurements. Additionally, the mooring of a ship over a long period of time may be logistically challenging and costly.

Acoustic Doppler Current Profiler (ADCP) Method

ADCP flow meter is now a more advanced and effective technique of measuring coastal currents. ADCPs have the capability to monitor water currents across a broad vertical extent and provide high-resolution data on the velocity profile of the water column. ADCPs are installable on various platforms including ships, buoys, and the ocean floor. Shipborne ADCPs can record measurements continuously during a journey along the coast or even during trans-oceanic cruises and chart out a huge region within a relatively short duration. Bottom-mounted ADCPs possess the ability to provide fixed-position, long-term measurements, and with these, scientists are able to explore long-term coastal currents trends.

4. On what basis is the working principle of ADCPs on the Doppler principle?

ADCPs operate on the Doppler principle. They send out acoustic pulses into the water. These pulses bounce off suspended particles such as sediment, plankton, or bubbles in the water. If the water is in motion, the frequency of the reflected pulses changes. The ADCP can calculate the relative velocity of the water from this frequency change by measuring it.

Most ADCPs contain multiple transducer beams, typically four or more, directed in different directions. The multi-beam configuration enables the ADCP profiler to compute the three-dimensional velocity of the water. Through signal processing by these beams, the ADCP can generate a full image of the current velocity at different depths in the water column. The information collected by the ADCP can be processed in real-time or stored away to be analyzed at some later time, providing valuable data regarding the dynamics of the coastal currents.

5. What does one need for high-quality measurement of Port Mourant coastal currents?

In order to measure accurately Port Mourant's coastal currents, the instrument should possess certain significant characteristics. The instrument should be made of robust materials, small in size, light weight, low power consumption, and low cost. These characteristics make it possible for a large number of instruments to be used and provide full spatial coverage.

Titanium alloy casing ADCPs are highly recommended. Titanium alloy also offers excellent corrosion resistance, necessary for long deployment in the unforgiving sea environment. The alloy resists saltwater's corrosive properties and shields the ADCP's internal components against damage. It is also heavy and strong yet light, supporting the instrument's strength and ease of portability. This combination of features allows for accurate and sustained measurements of the coastal currents around Port Mourant.

6. How to Choose the suitable equipment for measuring current?

Based on Usage

The choice of ADCP depends upon its use. For measurements in ships, ship-mounted ADCPs are the most appropriate choice. They can provide real - time information as the ship traverses the water, covering a great distance in a relatively short time. For survey over long duration in a fixed location, bottom - mounted ADCPs are better suited. They can provide continuous information for extended duration, allowing researchers to examine long - term patterns in coastal currents. Floating ADCPs are convenient in monitoring the flow of water bodies across extensive domains, yielding relevant data regarding extensive - scale patterns of circulation.

The ADCP frequency should also be determined with respect to the water depth. For water depths of below 70m, 600kHz ADCPs are appropriate. They can record high-resolution data in shallow water. For depths of up to 110m, 300kHz ADCPs are more appropriate. For deeper waters, reaching up to 1000m, 75kHz ADCPs are the better option.

There are a number of popular ADCP brands available in the market, including Teledyne RDI, Nortek, and Sontek. But for cost - conscious individuals, the ADCP manufacturer China Sonar's PandaADCP is highly recommended. Constructed fully of titanium alloy, it provides great performance at a low cost. It is a perfect option for cost - conscious users who still need quality ADCPs for coastal current measurement. For further information, refer to their website: https://china-sonar.com/.

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