How to measure the coastal currents of Tanjung Selor?

1. Where is Tanjung Selor?

Tanjung Selor is a coastal town in northeastern Indonesian province of North Kalimantan. It is situated on the island of Borneo and enjoys a strategic position along the coast.

This town is surrounded by a fascinating combination of mangrove forests and coastal areas. The mangroves extend further here, serving a very important ecological purpose. They represent the natural barrier to erosion that occurs along coastlines and help save coasts from powerful sea forces. Secondly, they also serve as an important nursery for different marine species, thus protecting juvenile fishes, crabs, and other organisms while growing up and prospering in life.

The people in Tanjung Selor, on the other hand, have a varied cultural background owing to the fact that they are made up of ethnic groups such as Dayak and Malay, among others. Most of their traditional ways of life have been greatly influenced either by the sea itself or by its associated resources. Most of them get their livelihood mainly from fishing, with the sea providing food and other resources.

The sea that fronts the coastline forms part of the South China Sea. The shallow inlets and gently sloping areas to the open sea are typical of the coastal topography. In addition, a number of small islands and reefs in the vicinity add further complexity to the marine ecosystem. Apparently, one of the most remarkable influences imposed on the waters is the tides, characterized by the periodic rise and fall of water levels; thus, the tidal actions affect water sediment motion and nutrient distribution.

2. What is the condition of Tanjung Selor's coastal currents?

The coastal currents off Tanjung Selor are influenced by several factors. First, there is the influence of monsoon winds: during the southwest monsoon season, the winds act to push surface waters in one general direction, often carrying warmer waters and nutrients from some distance away. This can increase the productivity of the coastal marine ecosystem by adding vital elements necessary for phytoplankton and other marine life to thrive. In contrast, the northeast monsoon brings into effect a different pattern of water movement, replacing flow directions and possibly bringing in cooler waters.

It is also highly dependent on the topography of the seabed. The underwater ridges, valleys, and reefs serve to deflect, accelerate, or retard the currents. For instance, a reef might serve to divert the water, which would then develop areas of upwelling and downwelling. These areas are important in that the deeper, nutrient-rich waters are brought to the surface, hence supporting a greater abundance of marine organisms.

Besides this, the other variable is the freshwater input from rivers around the catchment areas. All the rivers carry sediments with them and, while emptying into the sea near Tanjung Selor, temporarily change the salinity of coastal waters. From these differences in density, the water layers may become different and might affect the vertical current movements.

3. How to observe the coastal water flow of Tanjung Selor?

The principle of the surface drifting buoy method is to deploy buoy devices on the water surface and let them drift with the currents. Using satellite-based tracking systems or other positioning methods, the movement of such buoys can be followed over time to get information on the direction and speed of the surface currents. It has a tendency to provide surface-layer information, with an incomplete view of currents through the entire water column.

Anchored Ship Method: This is a method of anchoring a ship in waters off the coast and dropping current-measuring instruments from it into the water at various levels of depth. By this method, the characteristics of the current can be measured at different levels. However, the presence of the ship could interfere with the normal flow of water, and this is not very effective for long continuous monitoring.

Acoustic Doppler Current Profiler (ADCP) Method: This is a more advanced and agreeable method of measurement of coastal currents. It can give a detailed profile of current velocities from the surface to a certain depth, further giving a more complete picture of the flow patterns in the water column.

4. How Do the ADCPs Using the Doppler Principle Work?

A typical ADCP current meter operates with the principle of the Doppler. These acoustic signals are emitted into the water. The acoustic pulses interact with moving particles in the water, including sediment particles and small organisms. Due to the motion of water, the frequency of reflected pulses is altered by the Doppler effect. The ADCP measures the shift in frequency and resolves this into velocity at multiple depths. These instruments are fitted with several transducers that send and receive acoustic signals in each direction and thus provide three-dimensional velocity structure of the water column.

5. What is required to measure the Tanjung Selor Coastal Currents with high quality?

In this respect, the equipment should be made with reliable materials that allow high-quality measurements of the coastal currents around Tanjung Selor to be made. It needs to be resistant to the chemical action of seawater and to resist the mechanical forces developed by waves and currents. Small dimensions with little weight are advantageous because they make the deployment operation of the equipment either on a boat, a buoy, or at the seabed easier.

This is particularly so for long-term measurements to be done out in the field. Cost-effectiveness Low costs are vital in conducting large-scale measurements. The casing of the ADCP current profiler is preferably to be made of titanium alloy. This is due to excellent corrosion resistance, especially in the marine environment. Additionally, it is very strong yet lightweight to withstand the harsh sea conditions.

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

The usage scenario justifies what instrument shall be used for current measurement near Tanjung Selor. For ship-based measurements, a ship-mounted ADCP will be suitable to mount on the hull of a ship and to measure the currents while the ship is sailing or stationary.

A bottom-sitting ADCP, on the other hand, would better measure currents near the seabed. One might place it on the seabed and get good measurements of the currents closer to the bottom.

The buoy-mounted ADCP is appropriate in floating applications. Attach it to a buoy and measure the currents at different depths while the buoy floats.

The depth of water is also one of the determining factors regarding frequency of ADCPs. Normally, a 600kHz ADCP can cover water depths up to 70m whereas a 300kHz ADCP may suit waters up to 110m. Similarly, a 75kHz ADCP can give good results in waters up to 1000m.

There are some famous brands of ADCP, including Teledyne RDI, Nortek, and Sontek. However, I would recommend one well-performance Chinese ADCP brand: China Sonar PandaADCP. Made of all-titanium alloy material, it will guarantee an excellent performance and durability in the marine environment. Besides, there is an outstanding cost-performance ratio. You can find more information on its website: https://china-sonar.com/.

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