1. Where is Sambas?
Sambas Regency actually comes under Indonesian West Kalimantan Province, which forms part of the island of Borneo and is located towards the western part. The place has considerable natural beauty combined with variable nuances of culture.
Geographically, it shares a frontier to the west with the South China Sea. The shoreline is dynamic and a vital part of the area. The sand beaches are interspersed with large areas of mangrove forests and estuaries. The mangrove forests are the most important ecological habitations along the coasts. They provide a protective barrier against coastal erosion, buffering the impact of the sea and storms. These mangroves serve as nurseries for a wide variety of marine life, including fish, crabs, and shrimp. Estuaries are areas of very high productivity, mixing fresh and saltwater where the rivers meet the sea and host rather specific ecosystems.
Another important dimension of Sambas refers to the human aspect. The population is composed of various ethnic mixtures, such as Malays, Dayaks, and Chinese. The local culture is highly vibrant, and the local fishing and farming methods still play a significant role within the community. Fishermen rely on the catch from the waters along coasts as part of a big economic activity. The fresh array of seafood and agricultural products characterizes the local markets. In this place, it has been an area for trade and cultural exchange as a point of contact for different seafaring communities throughout centuries.
2. What is the situation of the coastal currents near Sambas?
Various factors influence coastal currents near Sambas. Among those, tides are one of the major factors to determine the nature of currents. Semi-diurnal tide occurs in this area with two high tides and two low tides in a day. During high tide, sea water inundates estuaries and low-lying areas along the coast. This flooding of water is likely to bring into the shore waters nutrients from the open sea, and the salinity and temperature of the coastal waters may also fluctuate. At low tide, the retreat of the water uncovers the seabed and alters the current directions and velocities.
The equally forceful impact of the monsoon winds is strongly felt. The northeast monsoon passes over the area, locally known as Amihan, while the southwest monsoon, locally known as Habagat, makes its way over the area. These coastal currents sometimes get driven in one direction by the Amihan winds blowing in from the northeast. The Habagat winds from the southwest then come to change the current in its direction and at times produce stronger movements of water. These winds may induce upwelling, where deeper, richer nutrient waters are brought to the surface, increasing the productivity of the waters near the coast.
Another reason might be the seabed topography around Sambas. The extensive mangrove roots continuing into the water, sandbars, and shallow channels might also play a role in the deflection and retardation of currents. A change in depth where the generally shallow coastal waters abruptly deepen into the much deeper South China Sea could also be a cause for changes in current patterns. Besides, the run-off of freshwater from nearby rivers into the sea can alter the density and salinity of coastal waters and hence affect the currents.
3. Bagaimana cara mengamati aliran air laut pada wilayah pesisir Sambas?
3.1 Traditional and Advanced Measurement Methods
Measurement of the coastal currents of Sambas will need to be done with proper understanding of traditional and advanced methods. Traditional techniques include floats and drogues. These are simplistic devices deployed in the water, and their motions are followed with the purpose of estimating the current. Drogues are similar in this vein but are designed to be more submerged and thus less affected by surface winds. These methods, however, give limited results regarding accuracy and a full water column.
A more advanced, therefore easier, option is the Acoustic Doppler Current Profiler. ADCP current profiler operate based on the principle of the Doppler effect. A signal is sent acoustically into the water column. The signal bounces off of particles suspended in the water, like plankton and sediment. As the water current moves the particles, the frequency of the reflected acoustic signal is different from the original signal that was emitted. This frequency shift, often referred to as the Doppler shift, has a relation to the velocity of the particles and hence the velocity of the water current.
Typically, an ADCP would transmit several beams of acoustic signals at different angles. This enables it to measure the velocity of the water current in three-dimensional space. By analyzing the Doppler shifts from these multiple beams, the ADCP is able to give a detailed profile of just how the currents are flowing both horizontally and vertically within the water column. Subsequent data gathered with these can then be used in calculating the flow rate of the coastal currents, which finds an essential application in such areas as marine navigation, coastal engineering, and environmental studies.
3.2 Requirements for High - Quality Measurement
Several equipment requirements must be met if high-quality measurements for the coastal currents near Sambas are to be achieved. The Acoustic Doppler Current Profiler (ADCP) should be manufactured from a reliable material that can stand harsh marine conditions, which include immersion in saltwater, high pressure at different levels of depth, and impact from floating debris. The casing of an ADCP is preferably made of a titanium alloy. The corrosion resistance of the titanium alloy is excellent, thus very suitable for a marine environment where saltwater can easily corrode other metals rapidly. It has great strength and endurance to stand the pressures and stresses of underwater operations. Its relatively low density will contribute a lot to keeping the overall weight of ADCP lower, which again is desirable with regards to ease of deployment.
Size and weight are two very important factors in the ADCP flow meter. A smaller, lighter device would obviously be much easier to deploy and handle, for instance, on board a boat or on a buoy, then one would practically need a lighter ADCP doppler. Low power consumption is also very important, mainly in long-term measurements; the device should be able to run continuously and not frequently change the batteries or have a large power supply. Cost-effectiveness is another more important aspect. Price of ADCP needs to be reasonable to allow large-scale measurement.
3.3 Selection of Appropriate Equipment
In selecting appropriate equipment to measure the coastal currents of Sambas, several aspects need to be considered. Based on its deployment method, there are different types of ADCP profiler.
Ship-borne ADCP: This is an ADCP mounted on a ship. These are normally suited for those surveys that can be covered by the ship navigating along the coast. This way, a wide-range view of the coastal currents over a large area is available. The ship-borne ADCP can cover various locations and depths as it moves out, hence giving comprehensive information on the current patterns.
Bottom-mounted ADCP (sit-on-bottom ADCP): It is placed on the seabed and continuously provides measurements of the currents passing over it. It would be very useful in monitoring certain locations, such as near a coastal structure or an area of particular interest for marine ecological studies. For instance, if one is concerned with the effects of a new pier on local currents, then a bottom-mounted ADCP would be in a position to provide detailed and continuous data.
Buoy-mounted ADCP: This type of ADCP is attached to a buoy and can float freely in the water, measuring the currents around it. It has the advantage of reaching areas not accessible by ship or where one needs continuous monitoring from a fixed position in the water. An example would be its use in open waters near the coast of Sambas.
Apart from the deployment method, the second important aspect is the frequency of the ADCP. For water depths up to 70 meters, one can use a 600 kHz ADCP. This frequency actually provides high-resolution measurements for shallower waters, thus enabling the capture of more detailed measurements of the currents within this depth range. Where the water depth is up to 110 meters, an ADCP with 300 kHz will do. It provides a good balance between resolution and penetration depth, hence being popular with many applications for coastal current measurement in this depth range. For deeper waters, as much as 1000 meters, there is an ADCP designed for that depth-a 75 kHz model. It can measure currents deeper into the water column.
There are well - known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option with good quality, the China Sonar PandaADCP is worth considering. It is made of all - titanium alloy material, which not only ensures its durability and resistance to the marine environment but also provides an incredible cost - performance ratio. You can find more information about this product on their website: https://china-sonar.com/.
Here is a table with some well known ADCP instrument brands and moels.
Brand | model |
---|---|
Teledyne RDI | Ocean Surveyor ADCP , Pinnacle ADCP , Sentinel V ADCP , Workhorse II Monitor ADCP, Workhorse II Sentinel ADCP, Workhorse II Mariner ADCP, Workhorse Long Ranger ADCP, RiverPro , RiverRay , StreamPro , ChannelMaster etc. |
NORTEK | Eco, Signature VM Ocean, Signature ADCP, AWAC ADCP, Aquadopp Profiler etc. |
SonTek | SonTek-RS5, SonTek-M9, SonTek-SL, SonTek-IQ, etc. |
China Sonar | PandaADCP-DR-600K, PandaADCP-SC-300K, PandaADCP-DR-75K-PHASED, PandaADCP-DR-300K, PandaADCP-SC-600K etc. |
How to Measure Coastal Currents in Sambas?