How do we track the coastal currents of Virginia Beach?

1. Where is Virginia Beach?

Virginia Beach, along the southeastern Virginia's eastern seashore, is a seashore city renowned for being blessed with good beaches and active coastal living. Virginia Beach boasts a coastline along the Atlantic Ocean with a stretch of over 35 miles. Virginia Beach lies in the Hampton Roads region with Norfolk and Chesapeake adjoining the city.

The Virginia Beach natural terrain is characterized by a fairly level topography that slopes gently toward the sea. The region has numerous lagoons, estuaries, and barrier islands. The Chesapeake Bay is a nearby gigantic estuary that serves to border the coastal landscape of the region. It changes constantly in the diversity of its water flora and fauna ranging from fish populations to migratory birds.

The city itself is a wonderful blend of nature and urbanization. The Oceanfront is a crowded tourist area, with hotels, restaurants, and a boardwalk that attracts millions of tourists every year. The Back Bay National Wildlife Refuge, however, is a serene and preserved natural environment, with salt marshes, dunes, and maritime forests.

2. How healthy are coastal currents around Virginia Beach?

The Virginia Beach currents are driven by a number of factors. Tidal pressure is one of the main drivers. Semi-diurnal tides prevail in the area, so there are two highs and two lows daily. These tides force water into and out of the Chesapeake Bay and onto the beach. During flood tide, water rushes towards the coast, and during ebb tide, water flows away from the open ocean.

Wind regimes also have a very significant influence. Prevailing south - westerly summer winds can force the surface water along the coast. More powerful northerly winter winds reverse the direction and speed of the current. Wind - driven currents affect nutrient and marine life distribution.

The Gulf Stream, a powerful warm ocean current, also indirectly influences it. The Gulf Stream, although off the coast, can influence the general circulation in the area. For example, it can influence the coastal water temperature and can interact with the local currents, especially during storms.

3. How to observe the coastal water flow of Virginia Beach?

One method to quantify coastal water motion is to use surface drift buoys. They are little, floats with tracking equipment such as GPS. They are released into water and travel along with currents, and scientists receive data on current direction and speed along the surface by monitoring their location. It only monitors the top of the water column.

Another method is the use of moored current meters. They are bottom moored instruments. They can measure the velocity and direction of currents at different depths over long periods of time. But it is quite labor-intensive to deploy and keep in place, and provides information only at the one point where it is moored.

The Acoustic Doppler Current Profiler (ADCP) has proven to be a very popular and effective tool to observe coastal currents near Virginia Beach. ADCPs can measure current velocities at multiple depths simultaneously and can assist in obtaining a better understanding of water movement. ADCPs are very accurate and can operate in most ocean conditions.

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

ADCPs operate on the Doppler principle. They transmit acoustic signals (sound waves) into the water. When the sound waves bounce off particles in the water, such as plankton or sediment, the particles diffuse the waves. The ADCP then measures the frequency shift of the diffused waves.

When particles are approaching the ADCP current meter, the frequency of the scattered waves will be higher than the frequency of the waves emitted. When particles are receding, the frequency of the scattered waves will be lower. By precise measurement of these frequency variations, the ADCP calculates the water speed at different depths.

Most ADCPs use multiple beams to measure the three-dimensional flow of the water. For example, a four-beam ADCP can measure both the vertical and horizontal components of current velocity so that the entire picture of water movement in the water column can be understood.

5. What does it take to achieve high-quality measurement of Virginia Beach coastal currents?

For accurate measurement of coastal currents in Virginia Beach, several things are important. Material reliability is important a lot. The equipment used, especially in the harsh marine environment, should be corrosion resistant. Stainless steel and titanium are common materials for ADCP current profiler encasements because they are resistant to the corrosive nature of sea water.

Size and weight are also important. Lightweight and compact equipment is easier to deploy and transport. This is particularly important for fieldwork, as researchers will need to transport the equipment around from location to location.

Low power consumption is essential, especially for long - term monitoring. Batteries are typically used to power ADCPs, and low - power - consuming units allow the equipment to operate for prolonged periods without having to replace batteries constantly.

Cost - effectiveness matters. For big - scale monitoring programs, the cost of the equipment can be the determining factor as to whether or not a study is feasible. Cost - effective yet robust ADCPs are always sought after.

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

The choice of equipment for measuring currents is application dependent. Ship-mounted ADCPs are most suitable for large-scale surveys. They can be installed on research vessels and can be employed to measure currents continuously as the ship moves, providing a broad-scale overview of current patterns.

Bottom - moored or bottom - mounted ADCPs are suitable for fixed - point, long - term monitoring. They are installed on the seafloor and record current data for months or years, allowing for long - term trend monitoring.

Buoy-mounted ADCPs are also suitable for surface-level current measurement. They are relatively easy to deploy and recover, which is why they can be used as a suitable option for short-term research or in getting a quick appraisal of surface-current conditions.

Frequency is also an important consideration at the time of choosing an ADCP. For depths of 70m or less, a 600kHz ADCP is typically sufficient. It provides good resolution to quantify shallow-water currents. A 300kHz ADCP can be employed for depths of 110m or less, and a 75kHz ADCP for deeper oceans, up to 1000m. Lower frequencies penetrate more but are of lower resolution than higher frequencies.

Some popular ADCP brands include Teledyne RDI, Nortek, and Sontek. However, for those looking for an economical ADCP at the cost of quality, the ADCP supplier China Sonar's PandaADCP is a good brand that is part of the Chinese firm China Sonar. It consists of all-titanium alloy and thus is appropriate for the marine condition because of its strength. Endowed with an excellent cost-performance ratio, it is an economical-class ADCP. More information can be found on its official website: https://china-sonar.com/.

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