ADCP Application to Ocean Current Measurement in the Laaksaare harbour

1. Where is Laaksaare Port?

Overview of Laaksaare Port

Laaksaare is a relatively less-known but essential coastal maritime facility that does offer a critical perspective in the chains of local and regional trade networks. In terms of scale, it has a well - developed infrastructure to handle a variety of vessels and cargo. The throughput in the port consists of various types of commodities, which include fishing products, agricultural produce, and some light industrial goods. It has established shipping routes that connect it to nearby ports and fishing harbors for the transportation of these essential commodities.

Management and operation of Laaksaare port are orientated to efficiency and sustainability. It has teams responsible for vessel traffic management, cargo handling, and quality control. The port also cooperates with local fishermen and farmers by ensuring a fluent flow of their products. For instance, fresh fish and perishable agricultural products have special handling and storage facilities.

Facilities

The place has a range of facilities to support its port operations: several berths of variable tonnage capable of handling fishing boats, small- to medium-sized cargo ships, and other vessels; cranes and hoisting equipment adequate for the type of general cargo usually dealt with; storage facilities comprising cold storage for fish and dry storage for other goods. Besides these, the port provides a fueling station and simple maintenance facilities to ships.

Channel and Direct Shipping

The channel of this port is kept so that local vessels could pass safely. The depth and width of the channel correspond to the size of ships that operate in this area. Laaksaare port has a straight connection to neighboring ports and places of fishing, which is important for local fishing and trading. These straight links enable the goods being transported to save time and reduce the cost of transport.

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

Importance for Port Operation and Management

Measuring ocean currents is particularly important in Laaksaare port for the safety of fishing and cargo vessels. Captains can better navigate through the port area by knowing the pattern and velocities of the current. For example, during peak seasons when fishing involves high volumes of boat traffic, it can prevent possible collisions and ensure smooth entry and exit of boats.

This is beneficial for the effective functioning of the port. The existing patterns can be helpful in guiding how to use the berths and when loading and unloading should be scheduled. For example, if a berth has a strong tidal current, the port may adjust the working time or give some additional guidance to ships to effectively conduct the operation.

Moreover, from an environmental point of view, this knowledge of the ocean currents would be helpful in predicting the spread of any potential pollutants in case of any accidents. This port deals with fishing and some industrial material, so it becomes really relevant. Given these aspects, a better and easier measurement method, such as an Acoustic Doppler Current Profiler (ADCP), is highly desirable for ocean current measurement in Laaksaare port.

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

Principle of Measurement

The ADCPs work on the principle of Doppler. The ADCP current profiler sends out an acoustic signal into the water. In turn, this signal from the ADCP scatters or bounces off the moving water particles. Since the water particles are in motion due to the ocean current, they reflect the acoustic signal back to the ADCP with a shift in frequency due to the. The magnitude of this frequency shift, due to the Doppler effect, depends on the velocity of the water flow. By determining the frequency shift, the acoustic doppler velocity meter can compute the speed and direction of the water flow. By transmitting signals at several angles and at various depths, the acoustic doppler flow meter can produce a profile of the ocean current-the way the current changes with depth.

ADCP in Port Ocean Current Measurement Methods

Shipborne ADCP: A shipborne ADCP is installed on ships operating in the Laaksaare Port area. As the ship sails around the port, the ADCP flow meter continuously emits acoustic signals into the water below. The ship's movement allows the ADCP to cover a wide area and collect current data from different locations. For instance, it can be done during a normal survey of the port by a research or inspection ship that has a shipborne ADCP on board, which then can map current patterns over different areas of the port to build up a thorough understanding of the water flow situation.

Fixed ADCP: Fixed ADCPs are deployed in stationery locations of fixed positions within the port, such as on the seabed near important navigational areas or the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed position for a long period. The collected data is useful in analyzing the regular current patterns in specific areas of the port. For example, a bottom-moored ADCP profiler placed close to the entrance could record the currents flowing in and out, while enabling the study of the effects created by tides and other steady features of flow in the area concerned.

4. What is required for high-quality measurement of currents at Laaksaare Port?

Equipment Requirements

The equipment to measure these currents in Laaksaare Port would have to fulfill the following conditions for high-quality measurements: first, material reliability. The equipment must be able to withstand the harsh conditions of the marine environment: seawater is corrosive because of its salt content, and the equipment also faces pressure changes at different water depths and mechanical forces driven by waves and currents.

It should be smaller in size, lighter in weight, and with lower power consumption. Compact size will allow easy installations even from several locations within the port, whether onboard ships, on fixed structures like piers, or on the seabed. A lighter weight will reduce complications in installation and transportation. Lower power consumption ensures the equipment can operate for long hours without the need for changing batteries or exhaustive power supplies, which is highly relevant to applications that require long-term monitoring.

Cost is another important factor. The low cost will enable the port to deploy more measuring devices to monitor the currents over larger areas of the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance, which means it can maintain its structural integrity and functionality even when exposed to seawater for a long time. Its high strength - to - weight ratio allows for the construction of a durable yet relatively lightweight casing. For example, in the deeper areas of the Laaksaare Port where higher pressure of water is experienced, an ADCP housed in a casing made of a titanium alloy can overcome such pressures and ensure continued accurate current measurements.

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

Selection Based on Usage

Shipborne ADCP: Where the objective is to carry out wide-area surveys of the port waters, and the ship is operational, shipborne ADCP will be applicable. It can cover various sections of the port as the ship moves around, collecting a large amount of data that may give an overall understanding of the current situation in the port. This will be useful in mapping the general flow patterns and their variations across different areas of the port waters.

Sitting - bottom ADCP: For long - term and fixed - point monitoring of specific locations within the port, such as near important infrastructure or areas with complex current behaviors, sitting - bottom ADCPs are more appropriate. They can continuously record the current data at those fixed positions, providing valuable insights into the local current characteristics and any changes over time.

Buoy-mounted ADCP: In situations where it may not be convenient to install fixed equipment on the seabed or on ships, buoy-mounted ADCPs can be deployed. They float on the water surface and are able to measure the currents in the upper layers of the water column. They are relatively easy to deploy and can be relocated if needed, suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Frequency Selection

ADCPs are selected based on the water depth in Laaksaare Port. Generally, areas that have a water depth of up to 70 meters find the 600 kHz frequency of an ADCP quite sufficient since it can perform quite well in measuring currents with some precision for that relatively shallow depth range. For deeper waters up to about 110 meters, a 300-kHz frequency ADCP would be more appropriate. In cases of very deep areas of the port with water depth reaching up to 1000 meters, an ADCP with a frequency of 75 kHz is recommended for reliable profiling of the ocean currents at such great depth.

There are several well - known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, there is also an excellent Chinese ADCP brand - China Sonar PandaADCP. It is made entirely of titanium alloy material, which not only ensures its durability in the marine environment but also offers an excellent cost - performance ratio. For more information, you can visit its official website: (https://china-sonar.com/).

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