Application of ADCP to Ocean Current Measurement in Djibouti Port

1. Where is Djibouti Port?

Djibouti Port is in the Republic of Djibouti, situated on the southern shore of the Red Sea and near the Bab el - Mandeb Strait, a very strategic location which makes it a vital maritime hub connecting both the Indian Ocean and the Mediterranean Sea through the Suez Canal.

Port Scale and Throughput

In the last few years, Djibouti Port has gained incredible momentum in development. It is a multifunctional port with large-scale infrastructure: the total length of the quays reaches several kilometers and can thus allow different types of vessels, from big container carriers to bulk carriers. In terms of throughput, it handles a substantial volume of cargo each year. This acts as a major trans - shipment point for goods for the destinations of East Africa, the Horn of Africa, and parts of the Middle East. There has also been a gradual increase in the container throughputs, as well as that in handling liquid bulk mainly of petroleum products, and of dry bulk commodities including coal, cement, and grains.

Routes and Business

The port has been hooked on various routes for international shipping. It has regular liner services to major European, Asian, and Americas' ports. The various business activities engaged in at the Djibouti Port are container handling, bulk cargo handling, and the provision of port-related services like ship repair, bunkering, and warehousing. It also plays a critical role in sustaining the local economy of Djibouti, while simultaneously facilitating trade for other neighboring landlocked countries such as Ethiopia.

Port Management and Operations

The Djibouti Port is under the management of the Port of Djibouti Authority. Such management invests much in ensuring high-quality services, efficiency in cargo handling, and continuous infrastructure development. The work there is greatly computerized, some areas, with modern cranes and handling equipment to enhance the speed of loading and unloading. Safety and security are also top priorities, with strict regulations and surveillance systems in place.

Port Facilities

The port is equipped with a variety of facilities. There are multiple berths for different types of vessels, including dedicated berths for container ships, oil tankers, and general cargo ships. The port also has large - scale storage yards for both dry and liquid cargo. For container handling, it has modern container cranes with high - lifting capacities. In addition, there are facilities for ship maintenance, including dry - docks and repair workshops.

Channels and Direct Navigation

Djibouti Port has well-maintained navigational channels. The main channel is dredged regularly to ensure adequate depth for large-draft vessels. In addition, the port has direct lines of shipment to many major international ports, which, besides promoting efficiency in trade, also enhances its status as a regional shipping hub.

2. Why do we need to measure the ocean currents in the Djibouti Port?

The measurement of ocean currents in Djibouti Port is important for many reasons. First, current data is important in the management of port operations; it provides an optimization of vessel berthing and unberthing. Strong or unpredictable currents may interfere with ship maneuvering. By knowing in advance the current speed and direction, pilots can better plan their approach and departure, reducing the risk of accidents and improving the overall efficiency of port operations.

Secondly, the knowledge of currents is useful in the handling of cargo. Currents can easily interfere with the stability of the ships when cargo is being loaded or offloaded. For example, in the case of bulk cargo, inadequate flow of currents results in shifting of the ship, which might lead to damage of cargo or the ship itself. In this situation, having current data in real time, modifications can be done in handling the cargo accordingly by the port operators.

Besides, the measurement of currents is important in the protection of the environment within the port area. Currents help in dispersing pollutants. With the help of current measurements, the spread of oil spills or other contaminants can be better predicted by the port authorities to take necessary preventive and cleanup measures in due time.

In a nutshell, precise ocean current measurement is crucial for the safe, efficient, and environmentally friendly functioning of Djibouti Port. Among these, the Acoustic Doppler Current Profiler(ADCP) has become a more advanced and convenient measurement method.

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

Principle of Measurement by an ADCP

The ADCPs work on the principle of the Doppler effect. When an acoustic wave is emitted from the ADCP to moving water particles, the frequency of the reflected wave will shift. If the water is moving towards the ADCP, the frequency of the reflected wave will be higher than the frequency emitted-positive Doppler shift-and if it is moving away, the frequency will be lower-negative Doppler shift.

The ADCP measures this frequency shift to calculate the velocity of the water particles. The ADCP current meter may profile the vertical distribution of the current velocity by emitting acoustic pulses regularly and analyzing the Doppler-shifted echoes from multiple depths.

ADCP in Port Current Measurement - Specific Methods

Ship-borne ADCP

One ADCP is installed on the hull of a moving ship. The ship, while moving, continuously measures the velocity of the current at different depths from the ship. This is useful for large-scale views of current patterns in the port area; it covers wide areas relatively fast and gives data on how the currents vary across different parts of the port.

Fixed ADCP

A fixed ADCP is deployed at a specific location in the port, such as on the seabed or attached to a pier. This type of ADCP flow meter provides continuous, long-term measurements of the local current conditions. It is ideal for monitoring the current characteristics at critical points in the port, such as near berths or in narrow channels, where accurate and long-term data are required for port operation planning.

4. What is needed for high - quality measurement of currents in Djibouti Port?

Equipment Reliability

High-quality measurement of currents in Djibouti Port will require highly reliable equipment. The harsh marine environment, including saltwater corrosion, strong winds, and waves may challenge the durability of the measurement device.

Small Size, Light Weight, and Low Power Consumption

It must be of small size and lightweight. This makes it easier to install in either ship-borne or fixed-type ADCP. A small-sized device also disturbs less the flow of water around it, and measuring errors will be minimal. It is also important to minimize power consumption, especially for fixed-deployed ADCPs that may rely on battery power or renewable energy sources like solar panels.

Low Cost

In order to have large-scale measurement in the port area, the cost of the equipment should be low to enable multiple deployments of ADCPs for a more comprehensive understanding of the current patterns.

Titanium Alloy Casing

The casing for the ADCP is preferably made of titanium alloy. Titanium alloy has a number of advantages. It provides excellent resistance to corrosion in sea water, and thus the long-term reliability of ADCP. Relatively light compared with other anti-corrosion materials, it can help to meet the requirement of lightweight. Additionally, the mechanical properties of the titanium alloy are good and enough to protect internal parts from damage.

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

Based on Usage

Ship - borne ADCP 

If the primary objective is to achieve a large-scale view of the current patterns in the port area for voyages on board, the ship-borne ADCP is the suitable tool. It will be easily mounted on the hull and can deliver information while the vessel is in motion.

Bottom - Mounted (Sitting - bottom) ADCP

For long-term monitoring of current conditions at a specific location, such as near a berth or in a channel, a bottom-mounted ADCP is more suitable. It can be fixed to the seabed and continuously collect data over an extended period.

Buoy - type ADCP

An ADCP of buoy-type is applicable when one needs to measure currents in areas where it is not easy to install fixed-type devices or when a more mobile measurement platform is required. It can drift with the currents, providing data on the movement of the water mass.

Based on Frequency

Normally, the depth of the water regulates the frequency of the ADCP. Up to 70m depth in water, an ADCP produces a frequency approximately in the order of 600 kHz, enabling high-resolution measurements in shallow enough waters. On the other extreme, if water depth goes as high as up to 110 meters then use a 300 kHz ADCP. When in approximately 1000 meters, make a switch to using a 75-kHz lower-frequency.

There are some famous brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those looking for affordable yet high-quality options, the Chinese brand China Sonar PandaADCP is highly recommended. Made of all-titanium alloy material, it assures excellent corrosion resistance and strong durability. It offers an excellent solution to ocean current measurement in Djibouti Port, with an incredible cost-performance ratio. For more details, you can log onto their website at (https://china-sonar.com/).

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