How to measure water current of Pibor River?

1. Where is Pibor River?

The Pibor River is a major river in eastern South Sudan, flowing through a region that is a mix of savannah and semi-arid landscapes. The river is an important lifeline for the local communities that live along its banks.

Along its banks, there are numerous small villages and settlements of the indigenous people. These communities have a deep connection with the Pibor River as it provides them with water for drinking, cooking, and bathing. The river also supports their agricultural activities, enabling the growth of crops during the rainy season. This surrounding is full of wildlife, with a wide variety of antelopes, zebras, and many more dependent on the river for their water needs. The path that the Pibor River travels through also has acacia trees among other vegetation that contribute to the region's unique beauty.

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

The flow rate of the Pibor River is highly influenced by the seasonal rainfall in the region. During the wet season, which usually occurs from [mention the months of the wet season], the river witnesses a sudden rise in flow. The water rushes downstream with a relatively high velocity due to heavy rains in its catchment area. The discharge can be substantial, sometimes reaching [estimated high - flow discharge in cubic meters per second].

In the dry season, however, this rate goes down dramatically, and at times the river may just have a narrow stream with very low velocity. In the rainy season, it is expected to be in this range, from 0.2 to 0.6 meters per second, whereas the discharge could also go as low as ____ cubic meters per second during its low flow. These fluctuations in flow rate directly impact the local ecosystems and affect the livelihoods of people who depend on the river.

3. How to measure water current of Pibor River?

There are several ways by which the water current of the Pibor River is measured:

Velocimeter method: It includes the use of mechanical or electrical velocimeters. These devices are submerged in water at varied depths and points within a river by operators. Velocimeters directly measure the speed of the flow of water at any particular point they are positioned. This technique requires considerable manpower and consumes time, especially if a complete knowledge of the current profile regarding different depths and locations within a river is required.

Acoustic Doppler Current Profiler (ADCP) method: ADCP current meter is a more advanced technique. It emits acoustic signals into the water column and analyzes the Doppler shift of the reflected waves. This allows it to measure the velocity of water at multiple depths simultaneously. Compared to the velocimeter method, ADCP flow meter can provide a more detailed and efficient picture of the river's flow conditions.

Buoy method: Buoys with sensors or tracking devices are placed on the surface of the Pibor River. The movement of the buoys over time will provide an estimate of the surface current speed and direction. This method mainly deals with the surface flow and may not give a correct representation of the conditions at deeper depths.

The currently established ways include the ADCP meter method among others, which is believed at the moment to be advanced, relatively more convenient in measuring water current of the Pibor River due to its details providing multi - depth data with relatively little effort.

4. How do ADCPs using the Doppler principle work?

The ADCPs work on the principle of the Doppler principle. They send acoustic pulses into the water at a known frequency. As these sound waves hit moving particles in the water, the frequency of the reflected waves is altered. The change is called the Doppler shift.

If the particles are moving towards the ADCP profiler, then the reflected frequency is higher than the emitted frequency, and if they are moving away, it is lower. By precisely measuring this frequency shift, and knowing the angle at which the acoustic signals were emitted and received, the ADCP can calculate the velocity of the water at different depths. Most times, several transducers on an ADCP current profiler are mounted in a different orientation to measure flow velocity in different directions-including both horizontal and vertical components. This helps create a very detailed profile of the water current within the river.

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

The equipment for measurement of currents of the Pibor River should possess certain characteristics that ensure high-quality measurement. First of all, it is necessary that the materials used in the manufacture of measuring devices be reliable. Equipment should bear all the influences of the river environment, including impact that is probable from floating debris and sharp changes in the quality and temperature of water.

It should be of small size, light in weight, and with low power consumption. A compact design allows for easier deployment and retrieval, especially in a region where access to the river might be challenging due to the lack of infrastructure. Low power consumption ensures that the equipment can operate for extended periods without needing frequent battery replacements or external power sources.

The cost is another important factor for large-scale measurement. For ADCPs, titanium alloy is an excellent choice for the casing material. It has many advantages. The first one is that it has very excellent corrosion resistance, which means it can endure long-term exposure to the river water without significant damage. It is also tough and durable to resist mechanical stresses, especially those from water currents and impacts that occur accidentally. Additionally, it is lightweight in relation to a big deal of other metals, which is appropriate for the equipment applied in the water current measurement.

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

Choosing the right equipment for measuring the current of the Pibor River:. First, for measurement of horizontal cross-section of flow, Horizontal ADCP will serve the purpose. It is designed in such a way that flow characteristics can be precisely captured in the horizontal plane. For the vertical cross-section measurement, Vertical ADCP would be more suitable as the flow information it provides refers to a vertical line at varied depths.

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 provide clear and accurate measurements in the relatively shallower parts of the Pibor River. On the contrary, a 300 kHz frequency of ADCP can cover even water up to 110 meters deep and thus serves on the deeper parts of the river for effective measurement.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for a cost-effective yet high-quality option, the China Sonar PandaADCP is worth considering. It is made of all-titanium alloy material, ensuring its durability and reliability and offering an excellent cost-performance ratio. You can find out more about it on its official website: https://china-sonar.com/.

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