ADCP's Application to Ocean Current Measurement in Nueva Tabarca Port

1. Where is Nueva Tabarca Port?

Nueva Tabarca Port is located in a strategic position along the Spanish coast. It serves as a significant local maritime access point.

Port Scale and Throughput

While smaller than some of the major international ports, Nueva Tabarca has a stable output. It mainly takes small to medium-sized vessels, dealing in a wide assortment of local trade goods, including fishing products, local handicrafts, and some agricultural produce from the nearby regions. Its size is well-matched to the needs of the local community and coastal trade in the area.

Routes and Business

The port has routes connecting the facility to other nearby ports down the Spanish coast. It is easy to move goods inside and outside the port for consumption and trade with the help of such connections. As far as business is concerned, it is a significant hub for the fishing industry. The boats use it as a home base where they can unload the latest catch and pick up everything needed. It also has a small but growing tourism-related business, including boats for tourist excursions and ferry services to nearby islands.

Port Management and Operations

The port is managed with a focus on keeping it useful for the community. The management team oversees the berthing of vessels, ensuring that it is both safe and orderly. They further control the loading and unloading operations so that the flow of goods does not get too congested. The port authority works in collaboration with local associations of fishermen and small-scale traders to efficiently utilize the facilities available at the port.

Facilities of the Port

The Nueva Tabarca Port has basic but important facilities. It has berths with the typical length that could accommodate the usual size of vessels frequenting the port. In addition, it has a small-scale fish-handling area, with facilities for cleaning, icing, and packaging fish. Storage areas for fishing gear and other supplies are also available. For tourism, there are simple passenger terminals with waiting areas and ticketing booths.

Channels and Direct Navigation

The port's channels are maintained to allow for the safe passage of local vessels. The depth and width are sufficient for the boats operating in this area. Navigation is relatively straightforward, with well-marked markings, and a direct access to the sea that allows vessels to reach their fishing grounds or other destinations without major difficulties.

2. Why do we have to measure the currents of the sea in the Port of Nueva Tabarca?

Safety of Vessels

Ocean current measurement is important to guarantee the safety of fishing vessels and other small vessels in the Nueva Tabarca Port. Currents can affect the course and stability of these boats. In fishing vessels, operating most of the time in the relatively small and sometimes congested areas around the port, the knowledge of the pattern of the current is an aid to safe return to port, especially under bad weather conditions. A wrong estimate of the current may result in difficulties at docking, even accidents like collisions with other vessels or port structures.

Fishing Operations Optimization

For fishing, the knowledge of ocean currents is essential. Currents may determine the distribution of fish since most species of fish are usually concentrated in those areas of the ocean where currents can carry nutrients. By measuring the currents, fishermen are able to locate areas which may be productive in fishing. Also, in the operation of fishing boats, the knowledge of current speeds and directions can help in fuel efficiency and proper deployment of fishing gear such as nets and lines.

Tourism-related Navigation

Due to the development of tourism within the area, precise current measurements are necessary to ensure tourist boat trips can be made in safety and with as much comfort as possible. Tourists want a pleasant trip without incident, and having knowledge of the current patterns enables the boat operators to plan routes in such a manner as to avoid rough water due to strong currents and provide a pleasant trip.

Infrastructure Protection

Although the port of Nueva Tabarca may be relatively small, knowledge of currents is very important for the long-term protection of its infrastructure. Currents can cause gradual erosion around structures in the port, such as piers and breakwaters. Monitoring the currents enables the port managers to take necessary measures in advance to maintain the integrity of the infrastructures and avoid costly repairs. The ADCP current meter does the job with much efficiency, effectiveness, and accuracy than the old methods.

3. How do ADCPs using the Doppler principle work?

ADCP Measurement Principle

ADCPs work on the principle of the Doppler effect. They transmit acoustic signals into the water. These signals scatter off the small particles in the water, like plankton and sediment. If the water is moving-in other words, if the current is carrying these particles-the frequency of the signal reflected back to the ADCP current profiler will be different from the frequency of the signal that the ADCP flow meter transmitted. The difference in frequency is called the Doppler shift and is proportional to the current velocity.

Mathematically, the Doppler shift ( $$ f_d $$ ) is related to the velocity of the water current $$ v $$, the frequency of the emitted acoustic signal $$ f_0 $$ and the speed of sound in water $$ c $$ by $$ f_d = \frac{2v f_0}{c} $$. Using several acoustic beams-four or more-an ADCP can calculate the three-dimensional velocity components of the water current at different depths in the water column.

ADCP in Port Current Measurement-Specific Methods

Ship-borne ADCP

Ship-borne ADCPs can be installed on fishing boats and tourist vessels operating at the Nueva Tabarca Port. In this way, while these boats sail in and around the port and its limiting waters, the ADCP measures the current velocities along their paths. Therefore, the mapping of the current patterns in those areas where these vessels ply is quite practical, providing valuable information on the current condition relative to fishing as well as tourism purposes.

Fixed ADCP

Fixed ADCPs will be installed at points of importance around the port, like on the seafloor at the entrance or at the extremity of piers. These instruments continuously provide point current measurements in the long term. In the case of the Nueva Tabarca Port, they would provide current condition monitoring that may affect vessel entrance and exit or stability of its infrastructures.

4. What is required for high-quality measurement of Nueva Tabarca Port currents?

Reliability of Equipment

The ADCP meter equipment must be made tough for it to give reliable current measurement in Nueva Tabarca Port. Since the environment is marine, it should be resistant to saltwater corrosion, varying temperature, and mechanic stresses due to wave and boat movements. It should be constructed with quality materials to ensure that accurate and continuous operation of the ADCP profiler would be possible for a long period.

Small Size, Light Weight, and Low Power Consumption

A small and lightweight ADCP is therefore advantageous, as it is going to be attached to the comparatively small vessels working in the port. It would not affect adversely the performance or the handling of the boats. For fixed ADCPs, a small size allows their installation in those limited spaces which are available inside the port area. Another important point is low power consumption, which would allow longer-term operations, especially for fixed ADCPs relying on battery power or other limited energy sources.

Low Cost

To encourage widespread use of current-measurement equipment in Nueva Tabarca Port, cost-effectiveness is key. A lower-cost ADCP makes it more accessible to the local fishing community and small-scale tourism operators. This allows for more comprehensive current-monitoring, which in turn enhances the safety and efficiency of operations in the port.

Titanium Alloy Casing

It is an advantage that the casing of ADCPs is made from a titanium alloy. For such purposes, titanium alloy shows excellent corrosion resistance for long-term exposure in saltwater conditions at the port. Besides, it is resistant and light, hence responding to strength and easiness for manipulation. This material resists pressures and stresses linked to the marine environment and therefore is suitable for ADCPs used in Nueva Tabarca Port.

5. How to Choose the Right Equipment for Current Measurement?

Based on Usage

Ship-borne ADCP

Ship-borne ADCPs are mounted on vessels that move around the port and its adjacent waters. For the fishing boats and tourist vessels in the case of Nueva Tabarca Port, they offer a means of acquiring real - time current information while the boats are on travel. They help in navigating, fishing operations, and comfort for the tourists.

Bottom-mounted (Sit-on-bottom) ADCP

Bottom-mounted ADCPs are ideal for long-term, fixed-location measurements. In Nueva Tabarca Port they can be deployed close to the main infrastructure or in locations where one wants to have a good knowledge of the current at a particular point, like at the entrance of the port, for incoming and outgoing currents.

Buoy-mounted ADCP

Buoy-mounted ADCPs can be installed in areas where a floating platform is more appropriate. They can provide current measurements in open-water areas around the port or in regions where bottom-mounted installations may be difficult.

Based on Frequency

• The choice of ADCP frequency depends on the water depth. In Nueva Tabarca Port: For coverage over water depths to about 70 m, for instance, use the 600 kHz ADCP, which gives highly resolved measurement results in this relatively shallow area close to a port; such measurements of current patterns come very useful for regions where most vessels of the given place operate.
• A 300kHz ADCP can be used for water depths up to approximately 110m. It offers a good balance between resolution and range and can be used for areas with slightly deeper waters around the port.
• A 75kHz ADCP will be for deeper waters, like up to 1000m. Though the port may not have such extremely deep areas, this frequency can serve very well for the adjacent deeper waters or expansion in the future for measurement at deeper places within the port area.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for a cost-effective option, the Chinese brand China Sonar PandaADCP is worth considering. It is made of all-titanium alloy materials, ensuring durability in the marine environment, and offers an excellent price-performance ratio. You can find more information at (https://china-sonar.com/).

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