How can we measure the Coastal Currents of Pontianak?

1. Where is Pontianak?

Pontianak is a bustling city situated in the Indonesian part of Borneo. It serves as the capital of the West Kalimantan province. Geographically, the position is near the equator and has therefore been endowed with a tropical climate. The city is cosmopolitan, with various ethnic groups being constituted by the Dayak, Malay, and Chinese peoples.

Pontianak borders the South China Sea. The coastal waters are important to both the local ecosystem and economy. Marine life in the waters includes plenty of colorful tropical fish and numerous crustacean species. The coastline is characterized by mangrove forests, natural barriers against erosion, and a cradle for many water organisms. The activities include fishing and trade that, together, form a considerable revenue stream, hence the ports are busy with the regular influx of fishing boats and small cargo vessels.

2. What is the situation of the coastal currents near Pontianak?

It is indeed there, owing to many factors affecting the coastal currents near Pontianak. Among them, the contribution of monsoon winds is predominantly important. The winds push the surface waters during the southwest monsoon, resulting in a shift in the current patterns. Tidal forces cause much of this. Gravitational attraction of both moon and sun creates tidal currents that ebbs and flow along coasts.

The range of the tides is also influenced by local bathymetry-undersea topography. Underwater relief can deflect and change the movement of water in an area, with its seabed shapes such as ridges or valleys. The river discharges, coming from many rivers around the area, including the Kapuas River, add to the coastal currents. Probably the fresh water being discharged into the sea from these rivers may create density differences and thus influence the dynamics of the current.

3. How to Observe the Flow of the Coastal Water in Pontianak?

Many means can be used in observing the flow of water in coastal Pontianak. These include traditional methods such as a surface drifting buoy method. In this method, buoys are set loose into the water and their movement over some time tracked. Fitted with GPS or other tracking devices, these buoys record their position and the direction in which they are carried by the currents.

Another technique used is the anchored ship method. A ship is anchored in a specific location and from that ship, current meters can be launched, which can measure the speed and direction of water flow in different depths. This technique also has its drawbacks because the position of the ship could get disturbed due to winds and waves; hence, it is not effective for long-term and wide-area measurements.

The more advanced and convenient method is the Acoustic Doppler Current Profiler (ADCP) method. ADCPs can measure a wide range of depth water current velocity profiles. They use sound waves to detect the motion of particles in the water to give a more accurate and detailed picture of the structure of the current.

4. Principles of working of ADCPs by the Doppler principle:

ADCP profiler work on the principle of the Doppler effect. They send out sound pulses into the water. Due to the Doppler effect, as the sound waves interact with particles in the water-sediment particles or small organisms-the frequency of the reflected waves changes. If the particles are moving towards the ADCP flow meter, then the frequency of the reflected wave is higher than the emitted wave; if they are moving away, it is lower.

It analyzes the frequency shift of the reflected sound waves to compute the velocity of the particles and hence the current water velocity. The ADCP current profiler can emit sound pulses in various directions, thus enabling the measurement of the three-dimensional space current velocity at different depths. In this way, a detailed profile is obtained for the current from the surface to the seabed.

5. What is required for high - quality measurement of Pontianak coastal currents?

Materials used for high-quality measurement of coastal currents in Pontianak must be reliable. The overall size of such equipment should be small to allow efficiency in deployment and retrieval, especially with areas that do not have full access or in small vessels. It must be lightweight to provide flexibility in installation.

This is particularly important for long-term measurements, where the measurement setup has to be powered either by batteries or solar panels. Cost-effectiveness is another important factor in that more measurement sets can be deployed for large-scale measurements. The preferred casing material of the ADCP current meter is of titanium alloy. It is extremely resistant to corrosion, which is so vital in the aggressive marine environment of Pontianak. It has a very high resistance against the corrosive action of saltwater and other chemicals present in the water for a very long period of time.

Further, the titanium alloy is strong and resilient for the protection of the acoustic doppler flow meter internal components. The high strength-to-weight ratio allows for lightweight yet robust construction that meets the requirements of easy handling and reliable performance.

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

Usage shall be the first consideration when choosing the right equipment for current measurement in Pontianak. Appropriate for measurements from a moving vessel is the ship-borne ADCP. It is able to provide real-time current data while the ship is underway. Bottom-mounted ADCP is appropriate for measurement at a fixed location near the seabed. It shall keep tracking the current at a point continuously. When the measurement over a wide area is needed and not confined to catch a specific depth, a buoy-type ADCP can be used.

The choice of frequency also depends on the water depth. For water depths up to 70m, a 600kHz ADCP is usually appropriate. Where the depth is between 70m and 110m, a 300kHz ADCP will be more suitable while for very deep waters of up to 1000m, a 75kHz ADCP will be even better.

There are several well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, a highly recommended Chinese brand is China Sonar PandaADCP. It is made of all - titanium alloy material, offering excellent durability and performance. With an incredible cost - performance ratio, it provides a great option for measuring the coastal currents of Pontianak. You can find more information about it on the website: https://china-sonar.com/.

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