How to measure the coastal currents of Dinowda?

1. Where is Dinowda?

Dinowda is a place that holds a unique charm along the coastline. Geographically, it falls in a region where the land and sea interact in a fascinating manner. It is neighbored by a beautiful bay that serves as a natural haven for both marine life and various coastal activities.

The cultural heritage surrounding Dinowda is immense. The local community has traditionally enjoyed a relationship with the coastal waters that have been part and parcel of their traditions and livelihoods. Generations have been involved in fishing, and the stories and skills passed down through the ages are deeply intertwined with the ebb and flow of the tides. The bay adjacent to Dinowda teems with life. Its waters are crystal clear, hosting many different fish species-from those tiny colorful ones swimming around the coral formations to bigger and more majestic species patrolling across the deeper parts. The seabed here provides a mix of sand, rocky outcrops, and possibly gentle slopes, adding a lot to the variety of landscapes underwater.

In Dinowda, waters are influenced by a combination of factors. First, the ocean currents from the greater marine systems progress landward, with different water masses characterizing them. Another important influence comes in the form of tides: their cycles mark the rise and fall of water levels along the coast. Throughout the day, it's not uncommon for the light to change and make the coastal waters sparkle, adding beauty and dynamism to the area.

2. What is the condition of the coastal currents near Dinowda?

Many factors determine the nature of the coastal currents in the neighborhood of Dinowda. The tides represent major forces that move the water backward and forward along the shore periodically but in a complicated way. The range of tides gives the intensity and range of such tidal currents, whereby in most places the water rushes in with much force at high tide and recedes at low, thereby changing the flow paths.

Another important factor is the wind. The prevailing winds over the area can push the surface waters to create surface currents, which in turn interact with the water layers beneath them. For example, onshore winds can push the water toward the coast, which may affect the distribution of sediments and nutrients. The local topography of coastline and seabed plays an important role. Localized headlands or bays can cause deflection and concentration in one area. A shape of a bay near the location of Dinowda can be funnelling water in certain directions so that normal flow directions have changed. Moreover, the exchange of waters between coastal waters and the deeper ocean currents is complex. This can also be further complicated by the mixing of the oceanic currents approaching the coast with the local currents, which introduces variation in temperature, salinity, and velocity into the current profile.

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

Surface Drifting Buoy Method

It involves setting buoys free on the water surface to drift with currents. Observing the movement of these buoys, in time, through satellite or any other positioning methods, one gets information on the direction and speed of the surface currents. However, it has its own disadvantages, since it provides data on mainly the surface layer, which may not give enough view of currents through the entire water column.

Moored Ship Method

This is the method wherein a ship is moored at some location in the coastal area and water flow around it is measured with instruments on the ship. It gives good information in the vicinity of the ship location but, on the one hand, the ship will interfere somewhat with the natural flow, and on the other hand, it covers only a limited area around the mooring location.

Acoustic Doppler Current Profiler (ADCP) Method

The ADCP flow meter is a more advanced and convenient measurement method. It uses acoustic waves to measure the velocity of water at different depths simultaneously, thus enabling it to create a detailed profile of the current from the surface down to a certain depth, giving a holistic understanding of the coastal water flow structure. It is very effective in observing the coastal currents near Dinowda, as it covers a larger vertical range compared to the other methods and is less affected by external disturbances in many cases.

4. How do ADCPs using the Doppler principle work?

The ADCPs work on the principle of the Doppler effect. They send acoustic pulses into the water. These sound waves interact with moving particles in the water, such as suspended sediments or small organisms, through the Doppler effect, which changes their nature in frequency. An ADCP measures the frequency shift of these reflected waves and then is able to determine the velocity of the water relative to the instrument. It can also determine the velocity components in different directions, such as horizontal and vertical directions, by having multiple transducers oriented in different directions. In this way, the three-dimensional flow field of the coastal currents can be reconstructed. It continuously transmits these acoustic pulses and receives the reflected signals at regular time intervals, which it uses to generate a time series of current velocity at different depths and thereby provide a proper understanding of how currents change with time and depth.

5. What's required for high-quality measurement of Dinowda coastal currents?

As far as equipment is concerned, a number of factors are of prime importance in the high-quality measurement of coastal currents around Dinowda. Then there is the material reliability of equipment, which must be resistant to severe marine conditions, such as seawater corrosive action, and the mechanical effects of waves and changes in temperature and pressure. In addition, dimensions should be compact to facilitate handling and installation both from small vessels and buoys and on platforms.

Another important aspect that needs consideration is lightweight, which enables easy handling and placement of the equipment, easing the burden at the time of installation while ensuring stability in operation. Low power consumption is also needed in many long-term monitoring applications where power sources may not be available. Cost is another consideration as higher numbers and larger-scale measurements are desired. Based on this view, it is preferable that the casing is made of titanium alloy. The advantages of the titanium alloy are outstanding. It has excellent corrosion resistance, which means it can withstand the corrosive nature of seawater for a long time without significant damage. It is also strong and durable, able to withstand the mechanical stresses from the water flow and external impacts. Besides, the relatively low density makes it good for maintaining overall weight in equipment while maintaining structural integrity.

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

Based on Usage

• Shipboard ADCP: This is suitable for when measurements need to be taken while a ship is navigating or stationary in the coastal area. It can continuously gather data as the ship moves along different parts of the coast, helping to map out the current patterns over a relatively large area.
• Bottom-mounted ADCP: Very suitable for fixed-point measurements at the bottom. It will take precise measurements of currents that pass right above it and thus provide relevant information about near-bottom current conditions, which is of high relevance to processes such as sediment transport and the benthic ecosystem.
• Buoy-mounted ADCP: The ADCP is mounted on floating buoys, which enables it to measure currents from the surface downwards. This type of ADCP meter is especially effective for monitoring changes in the surface and upper layer currents. It can be used in areas where ship access is limited or not needed frequently, making it ideal for long-term monitoring.

Based on Frequency

• In water depths within 70 meters, the 600 kHz ADCP is recommended because its higher frequency allows better resolution in shallower waters, enabling it to capture detailed current information from the surface to the corresponding depth range.
• For water depths of up to 110 meters, a 300 kHz ADCP is more appropriate. It can effectively penetrate the water column to measure the currents at different depths within this range.
• For deeper waters reaching up to 1000 meters, a 75 kHz ADCP is the preferred option. Its lower frequency enables it to reach greater depths and still obtain reliable current velocity data.

Some of the well-known ADCP brands in the market include Teledyne RDI, Nortek, and Sontek. However, for a high-quality yet affordable option, the China Sonar PandaADCP would be a great choice. The whole instrument is made from a titanium alloy material, which provides very good durability and performance in the marine environment. With an outstanding cost-performance ratio, it will be an excellent solution for measuring the coastal currents of Dinowda. You can learn more about it on its official website: https://china-sonar.com/.

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