ADCP in Krishnapatnam Port: Ocean Current Measurement

1. Krishnapatnam Port: Location and Introduction

Geographical Location

Krishnapatnam port is situated in the Nellore district of Andhra Pradesh, India. It is located on the East Coast of the country, which brings it at the forefront as an important maritime location.

Importance of the Port

The port has large-scale infrastructure with high-volume throughput. It handles a wide array of cargo, including coal, iron ore, containers, and various other bulk and general cargo. Shipping routes from Krishnapatnam Port span across the globe, facilitating extensive international trade. It serves as a crucial gateway for industries in the region, enabling the import of raw materials and the export of finished products.

The management of the port is effective and ensures that modern technologies are in place to maintain operational smoothness. Different functions, like vessel traffic control, cargo handling, and security, are each allocated a separate team. The automation of cargo tracking and vessel scheduling contributes to maximizing the overall efficiency of the facility.

Facilities within the Port

Berths

The port has numerous berths, each specially designed to handle a particular type of vessel. There are deepwater berths for large bulk carriers and container ships. These berths have modern mooring and docking facilities so that ships are handled in a safe and efficient manner. For instance, the berths have strong bollards and fenders to withstand the forces exerted by the vessels during docking and undocking.

Cargo-handling Equipment

Along the quay, a range of cargo-handling equipment is available. For bulk cargo like coal and iron ore, there are conveyor systems and large-capacity grabs. The conveyor systems are designed to transport the bulk materials from the ships to the storage areas quickly and efficiently. For container handling, gantry cranes with high-speed and precision-loading capabilities are used. These cranes can handle a considerable number of containers per hour, increasing the productivity of the port.

Storage Facilities

There are vast storage facilities for various types of cargo. For bulk cargo, there are large-scale stockpiles with proper drainage and dust-suppression systems. The stockpiles are well managed to avoid spillage and environmental hazards. The container yards in the port are well organized, each having a system that enables easy access and retrieval of the containers. The port also provides storage tanks for liquid cargo, such as petroleum products, which have safety features to avoid fire and spill containment.

Channel and Navigation Aids

The channel of the port is kept at a sufficient depth and width to allow for safe passage. Dredging operations are carried out on a regular basis to make it accessible for large-draft vessels. There are buoys, lighthouses, and radar systems to assist the ships during approach and departure. The radar systems provide real-time information on the position and movement of vessels in the vicinity of the port.

2. Importance of Measuring Ocean Currents in Krishnapatnam Port

Safety of Vessel Navigation

The measurement of the ocean currents is quite important from the point of view of vessel safety. The knowledge of current speed and direction is crucial for the ship masters while approaching the berths or navigating through the channel near the port. Strong cross-current near a berth can turn the docking operation into quite a difficult and hazardous affair. For example, a ship coming into a berth with a powerful current may wish to adjust both speed and angle of approach to smoothly and safely enter that berth. Accurate current measurements enable captains to make informed decisions that minimize the risk of collision and other accidents.

Optimization of Port Operations

Current data is important for the optimization of the operations of a port. By understanding the tidal currents and other regular flow patterns, port authorities can better schedule the arrival and departure of ships. This helps in efficient utilization of berths and other port resources. For example, it would be possible to time the arrivals during periods of favorable currents that speed up the loading and unloading process. Furthermore, it aids in better planning of cargo-handling operations owing to current patterns, therefore making the handling more productive.

Environmental Considerations

From an environmental point of view, ocean currents are important in cases of accidental spills of pollutants. Being that the nature of the cargo handled in the port consists of petroleum products and chemicals, it is important to determine where a spill would spread if this were to happen. Current data can be utilized for rapid deployment of containment and mitigation measures to minimize ecological destruction.

3. Operating Principle of ADCPs-Acoustic Doppler Current Profiler

Doppler Principle

ADCPs work on the principle of the Doppler effect. When an acoustic signal is transmitted by the ADCP profiler into the water, it scatters off the moving water particles. Due to the presence of an ocean current, these water particles are in motion and hence cause a frequency shift in the reflected acoustic signal received back by the ADCP flow meter. By the principle of the Doppler effect, this frequency shift is proportional to the velocity of the flow of water.

Calculation of Current Speed and Direction

By analyzing the magnitude and direction of this frequency shift, the Acoustic Doppler Current Profiler (ADCP) can calculate the speed and direction of the ocean current at different depths in the water column. By emitting signals at multiple angles and repeatedly measuring, it can build a comprehensive profile of the ocean current, showing how the current varies with depth.

ADCP Deployment in the Port

Shipborne ADCP

One ADCP current profiler is installed on ships operating within the Krishnapatnam Port area. As the ship moves around during its normal activities, such as patrolling or conducting surveys, the shipborne ADCP continuously emits acoustic signals into the water beneath it. It can cover a relatively wide area as the ship navigates different routes, collecting current data from multiple locations within the port. For instance, if there is a routine check at the port by a research vessel installed with a shipborne ADCP, it can easily obtain the current patterns across different sections of the port, providing an overview of the entire water flow situation.

Fixed ADCP

The fixed ADCPs are put at some fixed, stationary positions within the port, such as at the bottom of the sea near critical navigation points or at the entrance/exit of the port. They monitor the ocean currents continuously at those fixed positions over an extended period. This long-term monitoring provides stable and consistent data that is useful for analyzing the regular current patterns in specific areas of the port. For example, a bottom-mounted ADCP installed near the main entrance of the port can measure the currents coming in and out with time, which will help in understanding the tidal influence and other persistent flow characteristics in that region.

4. Requirements for High - Quality Measurement of Currents in Krishnapatnam Port

Equipment Requirements

Material Reliability

The equipment has to be resistant to the harsh marine conditions for high-quality measurement. Seawater contains salts and other chemicals, which eventually cause corrosion. The equipment also needs to handle the pressure changes in different water levels and the mechanical forces from waves and currents. Materials used in the making of current-measuring equipment should be highly resistant to corrosion and mechanical tension.

Size, Weight, and Power Consumption

Smaller size, lighter weight, and lower power consumption are preferred. The compact size will enable installation in various locations in the port, whether on ships, on fixed structures such as piers, or underwater. The lighter weight will make installation and transportation easier. Lower power consumption ensures that the equipment can operate continuously for long periods without the need for frequent battery replacements or excessive power supply, especially in applications requiring long-term monitoring.

Cost-effectiveness

Cost is another important factor. The lower the cost, the more measuring devices the port authority can deploy to measure currents at more places in different 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 instance, in those parts of the Krishnapatnam port which are relatively deeper and thus have higher water pressures, an ADCP current meter with a casing of titanium alloy will be able to support such pressures without damage and give continued current measurements of good accuracy.

5. Selection of Equipment for Current Measurement

Usage-Based Selection

Shipborne ADCP

The shipborne ADCP is also fine for broad surveys of the port waters, mainly when the purpose is to conduct these while the ship is in operation. This unit covers various sections of the port while it sails along its routes, collecting many data points to give a broad overview of the general current status outside the port. That will be useful for mapping general patterns of flow and variations across different areas of the port waters.

Sitting-bottom ADCP

Sitting-bottom ADCPs are more appropriate when long-term and fixed-point monitoring of specific locations within the port is required, such as near important infrastructure or areas with complex current behaviors. 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 cases where the seabed or shipboard platforms are not convenient for installing monitoring equipment, buoy-mounted ADCPs can be used. They float on the surface and can measure the currents in the top layers of the water column. They are relatively easy to deploy and can be relocated if necessary, making them suitable for the observation of certain dynamic areas or hard-to-reach areas within the port.

Selection Based on Frequency

ADCPs are chosen based on frequency for the water depth in Krishnapatnam port. For places with a water depth of up to 70 meters, an ADCP current profiler of frequency 600 kHz is typically suitable, as it can ensure satisfactory current measurements in this reasonably shallow depth range. Where water is deeper, to about 110 m, a 300 kHz frequency ADCP current meter is more appropriate. For such really deep parts of the port with a water depth reaching up to 1000 m, it is recommended to employ an ADCP flow meter with 75 kHz for the profiling of ocean currents in this enormous depth reliably.

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.