How to measure the water current of the Uele River?

1. Where is the Uele River?

The Uele River is a major river in the Democratic Republic of the Congo. It is situated in the northern part of the country and is an important part of the Congo River system.

It passes through a wide expanse of land that covers rainforests, savannahs, and wetlands. Indeed, alongside these river banks lie several small villages, dispersed with indigenous communities, relying from their very aspect of existence--source for fish in their plates for good nutritious food to the kitchen use, drinking, and other house use like washing and bathing. The Uele acts as a source of riverine transport means in that region, providing trading interactions and communication access between people across settlements. The surrounding forests are home to a variety of wildlife, including elephants, gorillas, and a great number of bird species.

2. What is the flow rate of the Uele river?

The flow rate of the Uele River has considerable seasonal variation. In the rainy season, which usually starts from [state the particular months of the rainy season], a lot of water pours into the river from heavy rainfall in its huge catchment area. The river's flow becomes powerful and rapid, with a relatively high velocity and a substantial discharge. The discharge can reach values several times higher than during the dry season.

In contrast, during the dry season, the flow rate slows down. The water levels drop, and the river may become narrower in some sections. The average flow velocity during the dry season might range from [provide an estimated range, such as 0.2 - 0.6 meters per second], and the discharge could be as low as [mention an estimated low - flow discharge in cubic meters per second]. These fluctuations in flow rate have a significant impact on the local ecosystems and the livelihoods of the communities that depend on the river.

3. How to measure the water current of the Uele River?

There are several methods to measure the water current of the Uele River:

Velocimeter method

The traditional approach employs mechanical or electrical velocimeters. The instruments are carefully lowered into the river at different depths and locations along its length.

The basic idea of the current can be obtained by directly measuring the speed of the water flow at these particular points. However, this requires a lot of time and effort since several measurements have to be taken at different positions to develop a complete understanding of the river's current profile.

Acoustic Doppler Current Profiler (ADCP) method

ADCP current meter is a more modern and efficient technique. It works by emitting acoustic signals into the water column and then analyzing the Doppler shift of the reflected waves.

This enables it to measure the velocity of water at multiple depths simultaneously, providing a detailed and accurate picture of the river's flow conditions much more quickly than the velocimeter method.

Buoy method

This method involves placing buoys with either sensors or tracking devices on the Uele River surface. The movement of the buoys should be observed over time, which would give an estimated value of the surface speed and direction of the currents. However, this method in general provides information about the flow at the surface and will not be representative of other conditions at greater depths.

Among these methods, the ADCP current profiler currently is a more advanced and convenient way to measure the water current of the Uele River because it can provide detailed multi-depth data with relatively less effort.

4. How do Doppler Principle ADCPs work?

ADCPs rely on the Doppler principle. They emit acoustic pulses of a certain frequency into the water. The reflected waves have a different frequency when the sound waves come across moving particles in the water, like sediment particles or small organisms. This change in frequency is called the Doppler shift.

If the particles are moving toward the ADCP meter, then the reflected frequency is higher than the emitted one, while in case of motion in the opposite direction, the frequency is lower. Measuring this shift in frequency quite precisely and considering the angle of emission and reception of the acoustic signals, the ADCP can find the velocity of the water at different depths. The transducers on an ADCP flow meter are generally mounted in several orientations from one another to make measurements of flow velocity in many different directions, including the horizontal and vertical components of flow. This detailed profile gives a proper view of water current within the river and delivers substantial information about the rate and direction of flow in the case of any variation in depth.

5. What's needed for high-quality measurement of Uele river currents?

For high-quality measurement of the Uele River currents, a variety of factors is important, relating to the measuring equipment.

First, the materials used in the construction of the equipment have to be highly reliable. The devices must be able to resist harsh conditions of the river environment in the Democratic Republic of the Congo, including possible impacts from floating debris, variations in water temperature and quality, and strong water currents during the rainy season.

The second key point is that the size should be small, with low weight and power consumption. A compact design makes it easier to transport and deploy the equipment at the various locations along the river, especially considering difficult terrain and limited access in some areas. Low power consumption ensures that the equipment can operate for extended periods without the need for frequent battery replacements or external power sources.

The cost enables large-scale measurement campaigns, an important consideration. As far as ADCPs go, an excellent choice for casing material is titanium alloy. There are a number of advantages to the use of a titanium alloy. To begin with, it offers outstanding corrosion resistance and hence can stand up to long-term exposure in the river water without degrading. It is also tough and resilient, hence, it can resist mechanical stresses, such as those caused by water currents and accidental impacts. In addition, while strong, it is relatively lightweight compared to many other metals, making it an excellent choice of material for equipment applied in water current measurement.

6. How to choose the right equipment for current measurement?

In selecting the appropriate equipment for measuring the current of the Uele River, several factors must be considered.

First, according to the purpose of use, if the horizontal cross-section of the flow is targeted to be measured, then HADCP is preferred. It is specifically designed to capture the flow characteristics in the horizontal plane with high accuracy. On the other hand, for vertical cross-section measurements, the Vertical ADCP is more suitable because it focuses on providing detailed information about the flow at different depths along a vertical line.

Besides, different frequencies of ADCPs are suitable for different water depths. For example, an ADCP with a frequency of 600 kHz is well-suited for water depths within 70 meters. It can give clear and accurate measurements in the relatively shallower parts of the Uele River. Meanwhile, an ADCP profiler with a frequency of 300 kHz is more appropriate for water depths up to 110 meters, enabling effective measurement in the deeper sections of the river.

There are several well-known brands of ADCPs in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost-effective yet high-quality option, the China Sonar PandaADCP is worth considering. It is made with all-titanium alloy material, which not only ensures its durability and reliability but also offers an incredible cost-performance ratio. You can learn more about it on its official website: https://china-sonar.com/.

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