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

1. Where is Dobo port?

Dobo port is located in the Aru Islands of Indonesia. It is an important port in this remote but resource-rich area.

Port Scale and Throughput

The port has a relatively moderate scale. It serves as a key transportation hub for the local islands. The throughput mainly consists of fishery products, since the Aru Islands have a great fishing industry. Additionally, it handles some general cargo, such as building materials and basic supplies for the local population. The port plays a crucial role in the internal trade of the Aru Islands and also in connecting the islands to the mainland of Indonesia.

Routes and Business

Dobo port connects shipping routes serving the local islands and connects with other major ports in Indonesia. Domestically, it serves as a point of collection and distribution of fishery resources. The main business operation includes loading and unloading of fishing boats and small cargo vessels. This also extends services for the storage and processing of fishery products before shipment to other destinations.

Port Management and Operation

The port management will ensure that the port functions properly. In this regard, the management must ensure proper berthing, coordination of cargo transfer, as well as safety and security of the port area. Members of the operation team also liaise with the local fishing community and cargo handlers in order to manage the day-to-day activities.

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 small cranes and forklifts. The port also has cold storage facilities for fishery products to maintain their freshness. Additionally, there are storage areas for general cargo and a small - scale fueling station for vessels.

Channel and Direct Navigation

The port has a channel, which is maintained for safe passage of ships. The channel is marked with navigation aid buoys and simple signage to guide vessels in. The depth of the channel is adequate to cater for the vessel types visiting the port, and enables direct navigation for fishing boats and small cargo ships.

2. Why should we measure the ocean currents in the Dobo port?

Measuring ocean currents in Dobo port is essential for several important reasons. Firstly, for the safety of fishing vessels. The local fishermen rely heavily on their boats for their livelihood. By knowing the ocean currents, they can better plan their fishing trips and avoid areas with strong or unpredictable currents that could endanger their lives and damage their boats.

It is also very important for cargo ships to function efficiently. Knowing the current patterns helps in the docking and undocking of vessels. It allows the ships to approach the berths more smoothly, reducing the time and effort required for loading and unloading operations. This can also lead to cost savings in terms of fuel consumption.

Besides, current measurements are useful for the management of fishery resources. Currents can affect the distribution of fish stocks. By understanding the current patterns, better fishing strategies can be developed and the sustainable use of fishery resources can be ensured.

Moreover, from the point of view of ecology, the knowledge of ocean currents is helpful for predicting the dissemination of contaminants. In cases of accidental spills of oil or other contaminants, current data would be useful in effective cleanup and containment operations. Relatively, ADCP has a more advanced and convenient way of measuring these currents compared to traditional methods.

3. How do ADCPs using the Doppler principle work?

ADCPs are based on the Doppler principle. They emit acoustic signals into the water. These acoustic waves interact with moving particles in the water, such as plankton and suspended sediment carried by the current. When the waves bounce back, the frequency of the reflected waves changes. This change in frequency, called the Doppler shift, is related to the velocity of the moving particles and, consequently, the velocity of the ocean current.

These acoustic signals are emitted and received by several transducers on the ADCPs. By measuring the Doppler shift from different directions-usually in a two- or three-dimensional configuration-the ADCP is able to calculate the speed and direction of the ocean current at different depths.

ADCP in Port Ocean Current Measurement Shipborne ADCP

Shipborne ADCPs are installed on vessels. As the vessel moves in the water, the ADCP flow meter sends acoustic signals downward and around. Current velocity information is recorded as the ship travels across various areas of the port. The use of a vessel-mounted instrument allows it to be very mobile, hence giving a wide spread of measurement points. Its own movement, however, has to be taken into consideration to minimize errors in results.

Fixed ADCP

Fixed ADCPs are placed at fixed locations in the port, such as 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 is required for high - quality measurement of Dobo port currents?

For high - quality measurement of ocean currents in Dobo port, the equipment should possess certain characteristics. The materials of the equipment should be reliable. Since seawater is corrosive and may cause impacts from floating debris, a durable material is highly required.

As can be seen, the size of the equipment should be compact so that installation is easy to execute, especially in areas of limited space, such as on smaller structures or over rough underwater topography. Likewise, the lightweight design supports ease of installation and post-installation maintenance.

In general, low power consumption is preferable, especially for long-term monitoring. Equipment with high power requirements may face challenges with limited power supply options in the port area or frequent replacement of batteries.

Cost-effectiveness is another consideration. To measure the currents in the harbor comprehensively, one needs a lot of instruments at relatively low costs. It is recommended to choose an ADCP current profiler that has its casing made of titanium alloy. Titanium alloy has high resistance to corrosion in sea water, and the device will, therefore, be durable. It is also solid yet lightweight, as it can bear high pressures without weighing the device down considerably.

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 large areas of the port when the ship is operational, then shipborne ADCPs are appropriate. They can provide coverage over various parts of the port as the ship moves and are helpful in surveying the general current patterns.

Bottom - mounted (Sitting) ADCP: For long-term and fixed-point monitoring of specific locations, such as near important infrastructure like breakwaters or at the entrance of the port channel, bottom-mounted ADCPs are ideal. They provide stable data for understanding the local current characteristics.

Buoy-mounted ADCP: When it is not convenient to install fixed equipment on the seabed or on structures, and a floating monitoring point is needed to capture surface and near-surface current conditions, buoy-mounted ADCPs are the way to go.

Based on Different Frequencies

For water within the depth of 70m, one would want a 600kHz ADCP. That yields high-resolution current profiles for more shallowly located parts, like those in a majority part of the port in places near the shore or even in small bays.

For water within a depth of up to 110 meters, one would prefer using the 300kHz ADCP; these would work really well while providing the velocity measurements.

For deeper areas, such as the approach to the port where the water depth may exceed 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 current meter 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.