ADCP's Application to Ocean Current Measurement in the Port of Depapre

1. Where is the Port of Depapre?

The Port of Depapre is in the Papua region, a province of Indonesia. It is a coastal port catering to the local community and is an integral part of the regional transport system.

Port Scale and Throughput

The port is of a medium scale. Its throughput is mainly composed of local goods, mainly agricultural products, fishing resources, and some construction materials. It is an important link in the transport chain for these resources within the local area and to other nearby ports. It does not handle volumes comparable to those of a major international port, but it is vitally important to the economic activities of the region.

Routes and Business

The port does have a connection with local shipping routes to other coastal communities that border it, and domestically to other ports in Papua and some in the Indonesian archipelago. The major business engagement here is loading and unloading of fishing boats since fishing is the major occupation of the people in the area. It also handles transportation of agricultural produce from farms around it.

Port Management and Operation

The port management is focused on ensuring the smooth operation of the port. This includes the organization of berthing for the local vessels, the coordination in cargo handling, and maintaining a safe and efficient environment. The operation involves cooperation with local fishermen, farmers, and cargo handlers to manage the flow of goods.

Port Facilities

It is equipped with basic port facilities. There are berths suitable for small to medium - sized vessels such as fishing boats and local cargo ships. There are simple loading and unloading equipment like cranes and forklifts to assist in the transfer of cargo. The port also has storage areas for agricultural products and fishery resources. Additionally, there are facilities for the refueling of local vessels.

Channel and Direct Navigation

The port has a channel, which is dredged for safe passage. There are navigation aids such as buoys and basic signage that guide vessels. The depth of the channel is appropriate for the vessel types using the port, enabling fishing boats and small cargo ships to navigate directly.

2. Why should we measure the ocean currents in the Port of Depapre?

Measuring ocean currents at Depapre Port is important because the knowledge of current patterns is crucially needed by fishing boats and small cargo ships for safety. By understanding ocean currents, fishermen can therefore be able to plan their fishing and avoid dangerous current conditions which can capsize their boats.

Secondly, it is beneficial for the efficient operation of the port. Current measurements help in the docking and undocking of vessels. It allows ships to approach the berths more smoothly, reducing the time and effort required for loading and unloading operations. This is especially important for the small - scale operations in this port.

Besides, from an environmental point of view, it is useful to know currents. Currents can disperse potential pollutants such as an oil spill from a local vessel or discharge of wastes. In these instances, current data will help the port develop a better management and mitigation process for such potential incidents of pollution.

Moreover, current data is useful for the long-term planning and maintenance of the port infrastructure. The forces that the ocean currents exert in a long period may affect the strength of the structural facilities at ports. Acoustic Doppler Current Profiler (ADCP) offers a more sophisticated and more convenient measurement of these currents compared to the traditional approaches.

3. How do ADCPs using the principle of Doppler work?

The operation of ADCPs is based on the principle of Doppler. They transmit acoustic signals into the water. These acoustic waves scatter against moving particles in the water, including plankton and sediment carried by an ocean current. The reflected waves bounce back with a different frequency due to this interaction. The frequency shift-the so-called Doppler shift-is proportional to the velocity of the moving particles and hence to the velocity of the ocean current.

These acoustic signals are transmitted and received by several transducers located on ADCPs. Measuring the Doppler shift from different directions-usually in a two- or three-dimensional configuration-allows the ADCP profiler to compute the speed and direction of the ocean current at discrete depths.

ADCP in Port Ocean Current Measurement:

Shipborne ADCP

Shipborne ADCPs are mounted on vessels. As the ship navigates through the water, the ADCP current meter sends acoustic signals downwards and around. It gathers current velocity information as the ship traverses across the various sections of the port. The advantage of this technique is its mobility, which allows a wide range of measurements. However, it's important to account for the ship's own motion to obtain accurate results.

Fixed ADCP

Fixed ADCPs are deployed at fixed locations in the port, either on the seabed or on fixed structures like piers. They continuously monitor the ocean current at a particular point. This provides consistent and long - term data for understanding the regular current patterns in a specific area. The downside is that they cover a limited area around their installation site.

4. What’s needed for high-quality measurement of Depapre Port currents?

For high-quality measurement of ocean currents in the Port of Depapre, the equipment should have certain characteristics. The materials of the equipment need to be reliable. Given the corrosive nature of seawater and the possibility of impacts from floating debris, a durable material is essential.

The size of the equipment should be small in size to allow for easy installations, especially in cases with limited space, such as on smaller structures or in an area with complex underwater topography. A light-weight design is also preferable since it would ease installation and maintenance processes.

This has a low power consumption, hence highly important for long-term monitoring. Equipment that requires high power may be faced with challenges considering limited power supply options in the port area or the frequent replacement of batteries.

Cost-effectiveness is another consideration. In the port, affordable equipment means more extensive deployment for comprehensive current measurement. The casing of an ADCP current profiler should be made of titanium alloy. Seawater has very good corrosion resistance for the titanium alloy, and this will guarantee the service life of the equipment. Besides, it is of high strength and light in weight, which can bear high pressure and add less weight to the device.

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

Based on Usage Purpose

• Shipborne ADCP: If the purpose is to collect current data over a wide area of the port while the ship is in operation, shipborne ADCPs are appropriate equipment. They can cover various regions of the port when the ship moves, thus serving the purpose of survey and understanding the overall current pattern.
• Bottom-mounted (Sitting) ADCP: For the long - term and fixed - point monitoring of specific locations, like near important infrastructures such as breakwaters or at the entrance of the port channel, bottom - mounted ADCPs are suitable. They can provide data stably for understanding the local characteristics of currents.
• Buoy - mounted ADCP: Where installation of fixed equipment on the seabed or on structures is not practicable, yet there is a requirement for a floating monitoring point, buoy-mounted ADCPs should be deployed to enable the recording of surface and near-surface current conditions.

Based on Different Frequencies

• Within 70m water depths, the 600kHz ADCP has a very good resolution for the current profile in shallower waters. Therefore, it is also suitable for the relatively shallow-water parts of the port, near the shore or in small bays.
• In the case of water depths up to 110m, it would be advisable to have an ADCP flow meter with a 300kHz frequency since at these depths it can make the proper measurement of the velocities.
• For deeper areas, like the approach to the port where the water depth may be in excess of 1000m, a 75kHz ADCP is recommended. Its lower frequency allows it to reach greater depths and still obtain useful current information.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option, the China Sonar PandaADCP is worth considering. It's made of all - titanium alloy material and offers an excellent cost-performance ratio. You can learn more about it at (https://china-sonar.com/).

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