How to measure water current of Nile River?

1. Understanding the Basics of Water Current Measurement

What is water current?

Water current denotes the movement of water within a river. It can be impacted by various elements such as the incline of the riverbed, the volume of water flowing, and, in certain cases where the river is adjacent to the ocean, tide influences. It is typically gauged in terms of velocity, which tells how fast the water is flowing.

Why measure water current?

Measuring the current of the Nile River helps in several respects. It allows us to observe the speed of water flow, which is vital for managing water resources. For instance, it helps decide how much water can be used for irrigation, supplying drinking water, or generating hydroelectric power without negatively impacting the river's ecosystem. It also offers valuable data for studying the movement of sediment in the river, as sediment movement is closely tied to the water current. This information is useful for comprehending the river's shape and its long-term change.

2. Methods for Measuring Water Current

Direct Measurement Methods

• Current Meters: These are apparatuses placed directly in the water to gauge the velocity of the current. There are different sorts of current meters, such as mechanical and electromagnetic ones. Mechanical current meters usually possess a rotating part that spins at a rate corresponding to the water velocity. Conversely, electromagnetic current meters measure the induced voltage caused by the movement of conductive water through a magnetic field.
• Acoustic Doppler Current Profilers (ADCP): These are instruments positioned directly in the water for gauging the speed of the current. There are different kinds of current meters, like mechanical and electromagnetic varieties. Mechanical current meters usually contain a rotating part that spins in accordance with the water velocity. On the other hand, electromagnetic current meters measure the voltage induced due to the movement of conductive water through a magnetic field.

Indirect Measurement Methods

• Float Method: This is a simple and traditional method. A float is put into the river. The time needed for the float to travel a specific distance is measured. Subsequently, the water velocity can be determined by using the distance covered and the time taken. Nevertheless, this method has drawbacks. It only provides an average velocity of the surface layer of the water and might be affected by wind and other surface disruptions.
• Dye Tracing: A dye is injected into the river, and its movement is observed. By tracking the spread and movement of the dye, an estimate of the water current can be made. This method is useful for visualizing the flow patterns of the water but may not provide very accurate quantitative measurements of velocity.

3. Considerations for Measuring Water Current in the Nile River

Environmental Factors

• The Nile River has a intricate ecosystem. Thus, any measuring approach should be selected cautiously to reduce disturbance to the environment as much as possible. For example, when using ADCP flow meter, the acoustic signals need to be set at a frequency and power level that won't harm aquatic life.
• The sediment load in the Nile can also affect the measurement. High sediment concentrations may scatter the acoustic signals in ADCP doppler, reducing the accuracy of the measurement. In such cases, appropriate calibration and data processing techniques may be required.

Hydrological Characteristics

• The Nile has different flow regimes depending on the season. During the flood season, the water volume and velocity increase significantly. Measuring devices should be able to handle these variations and provide accurate data throughout the year.
• The river also has different sections with varying depths and widths. In deeper sections, ADCP meter with a suitable profiling range need to be used to ensure that the entire water column is measured accurately.

4. Data Collection and Analysis

Data Collection

• When using ADCP current profiler, the data collection process involves setting up the device at the appropriate location in the river. The apparatus is usually attached to a platform or a mooring system to keep it in a steady position. The ADCP current meter constantly transmits and receives acoustic signals and logs the data related to water speed at different depths.
• For other methods like current meters, the data collection may involve manual readings at regular intervals or the use of automated data loggers that record the measurements over time.

Data Analysis

• The data collected from water current measurements needs to be analyzed to extract useful information. In the case of ADCP instrument data, software is usually used to handle the raw data and convert it into significant velocity profiles. Statistical analysis can be done on the data to figure out parameters like the average velocity and standard deviation. The data can further be used to make flow maps of the Nile River, showing the velocity dispersion at different places and depths. These maps can be used for further studies and for making decisions related to water resource management.

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

According to the Use Purpose

• For horizontal cross-section measurement, a horizontal ADCP (HADCP) is a suitable choice. It is designed to measure the water current in a horizontal plane, providing information about the flow across a particular section of the river.
• For vertical cross-section measurement, a vertical ADCP is preferred. It can measure the velocity of the water at different depths in a vertical column, giving a detailed profile of the water current.

According to Different Depths

• Different frequencies of ADCP are suitable for different water depths. For example, a 600kHz ADCP is suitable for water depths within 70m, while a 300kHz ADCP is more appropriate for depths up to 110m.

Recommended Equipment

• A highly recommended ADCP brand is PandaADCP from China. This item is constructed using all-titanium alloy materials. This not only results in a lightweight product (for example, the PandaADCP-DR-600K-1000 weighs a mere 1.8kg) but also ensures its durability and reliability in the harsh marine conditions. It delivers outstanding performance at an incredibly reasonable price. For more info, go to (https://china-sonar.com/).

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

Brand	model
Teledyne RDI	Ocean Surveyor ADCP , Pinnacle ADCP , Sentinel V ADCP , Workhorse II Monitor ADCP, Workhorse II Sentinel ADCP, Workhorse II Mariner ADCP, Workhorse Long Ranger ADCP, RiverPro , RiverRay , StreamPro  , ChannelMaster  etc.
NORTEK	Eco, Signature VM Ocean, Signature, AWAC, Aquadopp Profiler etc.
SonTek	SonTek-RS5, SonTek-M9, SonTek-SL, SonTek-IQ, etc.
China Sonar	PandaADCP-DR-600K, PandaADCP-SC-300K, PandaADCP-DR-75K-PHASED, etc.