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

1. Where is Lembar port?

Lembar port is located on the island of Lombok in Indonesia. It is a significant maritime facility with various aspects contributing to its importance in the region.

Port Scale and Throughput

The port has seen continuous development and expansion over the years. It has a rather big area for port operations and is capable of handling considerable cargo volumes. Its annual throughput is quite diverse, comprising agricultural produce from the very fertile lands of Lombok, construction materials, and consumer goods. It has played a very significant role in promoting not only domestic trade within Indonesia, connecting Lombok to other islands such as Java and Bali, but also some international trade, serving as a very important gateway for the exportation and importation of local commodities.

Routes and Business

Lembar port is connected to numerous shipping routes. In Indonesia, it operates regular trips to and from almost all other major ports in the Indonesian archipelago, facilitating the proper dissemination of goods to all corners of the nation. Its development at an international level is rather gradual in its emergence as a critical link in trade with neighbors in Southeast Asia. Its business activities range from handling containers for easier transportation of cargo to handling bulk cargo like coal and grains. Furthermore, there are facilities for loading and unloading vehicles; this factor helps the tourism industry, seeing many tourists travel with their vehicles when going on trips in Lombok.

Ports Management and Operation

The port is managed by a professional team that oversees all aspects of its day-to-day functioning. This includes arranging berthing for ships based on their schedules and sizes, coordinating cargo handling processes to ensure quick and efficient loading and unloading, and maintaining the overall security and cleanliness of the port area. The operation involves close cooperation between different departments such as stevedoring companies, customs officials, and port maintenance crews to ensure seamless port activities.

Port Facilities: It is a modern port facility with functional facilities. The berthing facilities have variable lengths and depths to accommodate small coastal ships up to larger ocean-going cargo vessels. Modern cargo-handling equipment such as cranes, forklifts, and conveyor belts provide easy movements of goods in and out of the harbor. The port has warehousing facilities for the temporary storage of cargo before being moved to other destinations. Moreover, the refueling and maintenance of ships can be done to ensure the continuing voyage without any obstacles.

Channel and Direct Navigation

The port has a well-maintained channel that allows ships to enter and exit safely. The channel is regularly dredged to maintain the required depth for ships with different drafts. Navigation aids such as buoys, lighthouses, and modern radar systems are in place to guide ships during approach and departure, enabling direct navigation for vessels coming from different directions.

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

The measurement of ocean currents in the Lembar port is quite important from the point of view of its effective functioning and management. Accurate knowledge of current patterns will help optimize ship berthing and unberthing operations. By understanding the direction and speed of the currents, port authorities can schedule vessel arrivals and departures more effectively. For example, ships can be guided to berth along the direction of the current to minimize the effect of lateral forces during docking, hence reducing the possibility of damage to the ship and the berth structure.

It is very instrumental in ensuring the safety of ships moving in and out of the port. Strong or unpredictable currents may pose serious risks to vessels, especially those with larger drafts or carrying hazardous cargo. With precise current data, appropriate navigational warnings can be issued, and ships can adjust their speed and course accordingly to avoid accidents like collisions with other vessels or running aground.

Besides, the understanding of ocean currents helps in the environmental protection of the port area. Currents have an influence on the dispersion of pollutants such as oil spills or wastewater discharges. With the detailed information on currents, the port will be better prepared and able to effectively plan and implement measures for containing and cleaning up any potential pollution incidents, minimizing the impact on the marine ecosystem.

Besides that, in the making and maintenance of facilities at a port, such as a breakwater or quay wall, recent current data is badly needed. The impact of the forces exerted by ocean currents over time is great, and this influences the stability of such structures. An ADCP profiler offers a very modern and convenient means of ocean current measurement compared with the usual methods, allowing for information on current profiles to be procured in detail and in real time at varied depths.

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

The principle on which ADCPs work is the Doppler principle. They emit acoustic signals into the water. Where these acoustic waves encounter the moving particles in water, such as sediment particles or small organisms carried by the ocean current, the frequency of the reflected waves changes. This change in frequency is known as the Doppler shift and is related directly to the velocity of moving particles and hence to that of the ocean current.

Typically, ADCPs are fitted with several transducers that transmit and receive these acoustic signals in various directions. By measuring the Doppler shift from multiple directions, often in a three-dimensional or two-dimensional configuration, the ADCP meter can 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 operating in the port area. While the ship is underway, the ADCP flow meter continuously sends acoustic signals downwards and to the side. In this way, it collects data on the current velocity while the ship covers different areas of the port. The big advantage of this method is its mobility, allowing measurements in a wide range of locations within the port waters. However, in order to achieve accurate results, the motion of the ship itself has to be taken into consideration, and adequate calibration and compensation methods must be applied to correct for the possible errors induced by the movement of the ship.

Fixed ADCP

Fixed ADCPs are installed at fixed locations in the port on the seabed or fixed structures such as piers or buoys. They will measure that one place in the ocean current continuously for a long time. This will provide them the data of long-term and consistent type for comprehending regular current patterns in specific areas of the port. The shortcoming is that they give the current information of their surrounding area where they were installed, but they are extremely helpful in establishing reference data on currents for particular regions in a port.

4. What is necessary for the high-quality measurement of Lembar port currents?

In the measurement of ocean currents in the Lembar port, several factors concerning the equipment are very important. First, the materials of the equipment should be reliable; they should be able to resist the harsh marine environment, including corrosion from seawater, pressure at different depths, and impacts that may be caused by floating debris.

The size of the equipment should be small to provide easy installation, especially in areas with limited space on small buoys or locations with complex configurations of underwater structures. The apparatus should be as lightweight as possible to minimize challenges during handling at deployment and recovery operations, thus minimizing workload and risk.

Low power consumption is essential for long-term monitoring applications. A high power requirement can quickly become a challenge in terms of continuous operation, due either to limited power supply options within the port area or the frequent replacement or recharging of batteries.

Cost is another important factor. On a large-scale measurement effort in the port, affordable equipment can be deployed more extensively, providing a much better grasp of the current state of affairs across the waters in the port.

The casing of ADCP is preferably made of titanium alloy. Titanium alloy has a number of outstanding advantages. It has very good corrosion resistance in seawater, which provides long life for the equipment and its continued performance over time. It is also comparatively strong yet lightweight and thus resistant to high pressures at greater depths without adding too much weight to the overall device. In addition, it is biocompatible and will have fewer adverse effects on the marine environment or interfere with the acoustic signals of the ADCP current profiler.

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

Based on Usage Purpose

Shipborne ADCP: In a situation when the intention is to have current data over a wide area of the port, say during the operational work of a ship, such as regular surveys of a port or in the collection of data to update navigation charts, it is worth opting for the shipborne type. They cover different parts of the port during the movement of the ship.

Bottom-mounted (Sitting) ADCP: In cases when long-term and fixed-point monitoring of specific locations within the port is needed, like around critical infrastructure such as breakwaters or at the entrance of the port channel, bottom-mounted ADCPs will be suitable. They provide stable and continuous data for understanding the local current characteristics.

Buoy-mounted ADCP: For areas where it is not convenient to install fixed equipment on the seabed or on structures, or when a floating monitoring point is needed to capture the surface and near-surface current conditions, buoy-mounted ADCPs are ideal. They can be easily deployed and moved if necessary.

Based on Different Frequencies

For water depths within 70 meters, a 600 kHz ADCP is often a good option. It can provide relatively high-resolution current profiles in shallower areas, suitable for most of the port areas where the water depth is not extremely deep, like near the quay walls or inner harbor.

In water depths of up to 110 meters, the ADCP with 300 kHz would be better. This is because it could well penetrate the water column at this depth and measure current velocities very accurately.

For much deeper areas, such as in the approach channel of the port where the water depth may exceed 1000 meters, a 75 kHz ADCP is recommended. Its lower frequency allows it to reach greater depths and still obtain useful current information.

There are several well-known ADCP current meter brands in the market, including Teledyne RDI, Nortek, and Sontek. However, if quality and cost-effectiveness are pursued, then the China Sonar PandaADCP will be worth considering. It is made of all-titanium alloy material, combining durability with good performance. Offering a great choice for ocean current measurement in ports like Lembar, it provides an incredible cost-performance ratio. Learn more about it on its official website: https://china-sonar.com/.

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