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

1. Where is Lehtma Port?

Overview of Lehtma Port

Lehtma is a coastal port, which forms a very important transportation node in the area where it is located. It has a moderate size, with its throughput comprising all types of cargo, like agricultural products, building materials, and some light industrial cargo. The various shipping routes of the port connect it to other regional ports while contributing to the regional trade network. This is important in facilitating the transportation of goods that supply the local economy and the needs of the communities surrounding the port.

Port management and operations are divided according to a focus on efficiency and safety. There are vessel traffic management teams, cargo handling teams, and compliance teams. Activities at the port are coordinated with farmers and businesses at local levels to promote an efficient import and export traffic system. For instance, it provides facilities for the speedy loading and unloading of produce to preserve the freshness of agricultural produce.

Port Facilities

It is a useful facility at the port. The different-sized vessels, ranging from small fishing boats up to medium-sized cargo ships, can be accommodated in several of its berths. Along the quay are cranes and other loading/unloading equipment suitable for handling the common types of cargo passing through. There are also storage areas for different goods. Some of these warehouses are meant to preserve perishable goods, and others are for bulk storage of materials such as grains and building stones. Besides, the harbor has the basic facilities for resting the crews of the ships and supply points.

Channel and Direct Shipping

The channel of the port is kept at a depth and width that allows the passage of ships safely. Consequently, to ensure navigability, regular inspections and maintenance works are executed. About direct shipping, Lehtma port possesses direct connections to other important regional ports. To be more specific, it is often mentioned that these direct connections contribute to the reduction of both the time spent during shipment and the shipment cost, therefore, they enhance the role of this port in the regional trade.

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

Importance for Port Operation and Management

Measurement of ocean currents is of great importance in the Lehtma port. First of all, it is highly important for the safety of ships. Currents can give a great impact to a ship for navigation and for docking. For example, when a ship is coming to a berth, strong cross - current may give hard time for manoeuvring. Accurate current measurements allow captains to adjust their approach speed and angle, thus ensuring smooth and safe docking. This reduces the risk of collisions and other accidents that might disrupt port operations.

It is crucial because the new data enables the optimization of the port's operations. Present data enables better scheduling of ship arrivals and departures. In knowing tidal and other regular patterns of currents, port authorities can plan berthing spaces and handling equipment more judiciously. Productivity increases in that the co-ordination of loading and unloading activities is better.

Besides this, from the viewpoint of environmental concern, the ocean currents knowledge is useful in terms of possible incident flow-through dispersal of a pollutant. It will enable one to promptly respond to the problem to reduce or mitigate its environmental effects. Considering these relevant factors, an efficient and at-the-ease measurement method such as ADCP flow meter will be very beneficial for the measurement of ocean current in Lehtma port.

3. How do ADCPs that utilize the Doppler principle work?

Measurement Principle

The working of ADCPs is based on the principle of Doppler. When an ADCP current profiler emits an acoustic signal into the water, it bounces off the moving water particles. As the water particles are in motion due to the ocean current, they create a frequency shift in the reflected acoustic signal that is received back by the ADCP. According to the Doppler effect, the frequency shift is related to the velocity of the water flow. The ADCP current meter could work out the speed and the direction from such a frequency shift. Since the ADCP meter emits signals at multiple angles and different depths, it can create a profile of the ocean current, showing how the current varies with depth.

ADCP in Port Ocean Current Measurement Methods

Shipborne ADCP: A shipborne ADCP is installed on ships operating in the Lehtma port area. During the movement of the ship within the port area, the ADCP profiler continuously sends acoustic signals down into the water. Because of the movement of the ship, it covers a huge area and as such, can provide current data for a wide range of areas. By routine survey for instance, of the port with the use of a shipborne ADCP, attached to a research or inspection ship, data acquisition of the pattern of current across many parts of the port can be made to give an overview of the water flow situation.

Fixed ADCP: Fixed ADCPs are placed at specific, stationary locations within the port such as on the seabed near important navigational areas or at the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period. The data collected is useful for analyzing the regular current patterns in specific areas of the port. For example, a bottom-mounted ADCP at the entrance of the port can continuously measure the currents entering and leaving the port to obtain knowledge about the tidal influence and other regular flow features of that area.

4. What is required for a high-quality measurement of the Lehtma port currents?

Equipment Requirements

To get high-quality measurement of currents in Lehtma port, certain characteristics are essential for equipment. First of all, it needs material reliability. Since it is used in the sea environment, possible corrosion caused by seawater needs to be withstood. Seawater includes salts and many chemicals inside it, which have the capability to corrode any material over a time interval. The equipment also needs to resist the pressure variation resulting from changes in the depth of water and mechanical forces due to waves and currents.

The second desirable feature is smaller size, lighter weight, and less power consumption. The compact size makes the installation process at different locations in the port-maybe on ships, on fixed structures such as piers, or even on the seabed-easier to manage. A lighter weight makes both installation and transportation processes easier. Lower power consumption ensures that the equipment can be continuously operated for longer periods without frequent battery replacements or excessive power supply, in particular for long-term monitoring applications.

Cost is another important aspect. A lower cost would thus enable the port to implement a larger number of measuring devices to achieve more comprehensive current monitoring for various areas of the port.

Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferred to be made of titanium alloy. Titanium alloy has very good corrosion resistance, which enables the alloy to preserve its structural integrity and functionality even when exposed to seawater for extended use. Its high strength-to-weight ratio enables the construction of a durable yet relatively lightweight casing. For instance, where water pressure is greater in the deeper areas of the Lehtma port, an ADCP current profiler with a casing made of titanium alloy will be resilient to such pressure and still be able to provide accurate measurement of currents.

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

Selection Based on Usage

Shipborne ADCP: In cases where wide-area surveys of the port waters are to be carried out and the ship is operational, the suitable choice would be a shipborne ADCP. It can cover different sections of the port as the ship moves around, collecting a large amount of data in order to provide an overall understanding of the current situation in the entire port area. This helps in mapping the general pattern of flow and variations within different areas of the waters.

Sitting - bottom ADCPs: These are more fitted for fixed point, long - term monitoring of particular places in the port vicinity that may be crucial to infrastructure or zones of highly intricate current behaviors. They can continuously record the current data at those fixed positions with valuable insights into the local current characteristics and any changes over time.

Buoy-mounted ADCP: These are used when it is not convenient to install fixed equipment on the seabed or on ships. They float on the water surface and are capable of measuring currents in the upper layers of the water column. Being relatively easy to deploy, they can be easily relocated if necessary. Because of this, they are suitable for monitoring those dynamic areas or hard-to-reach areas within the port.

Selection Based on Frequency

The choice of frequency for ADCPs depends on the water depth in Lehtma port. For areas with a water depth up to 70 meters, an ADCP current meter with 600 kHz is normally a good option since it can deliver current measurements with quite good accuracy at such a relatively shallow depth range. For depths ranging up to about 110 meters, an ADCP profiler at a frequency of 300 kHz can be more advisable. In sections of the port where the water can get as deep as up to 1000 meters, an ADCP current profiler operating with a frequency of 75 kHz is recommended to ensure reliable profiling of the ocean currents at such great depth.

There are several well - known ADCP current meter brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, there is also an excellent Chinese ADCP flow meterbrand-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.