How to Measure Water Current of the Ubangi River?

1. Where is the Ubangi?

The Ubangi River is a major river in central Africa. It is a chief tributary of the Congo River. The head of the Ubangi River is in the Central African Republic, and it passes through the Democratic Republic of the Congo and the Republic of the Congo.

Going up its course, the Ubangi River cuts across different land features, running through tropical rainforest with thick canopy cover full of life, both in flora and fauna. Tall trees line up its banks, while hippos, crocodiles, and different types of fish inhabit its waters. It acts as an important means of transport through most of the forested areas.

It also flows through more open savannah areas where it provides water for stock and facilitates farmers' livelihood activities that depend on irrigation. The river is at the very center of this people's life, having stood for centuries as a place of trade, cultural exchange, and source of food through fishing.

2. What is the nature of discharge from the Ubangi River?

The Ubangi River has a very variable discharge rate, with its regime occurring through the combined actions of rainfall and the dry season. The river swells during the rainy season-between March and November generally-before heavy rains fall. Its flow increases greatly, the current is powerful, and it can inundate wide areas of the floodplain, holding a unique wetland ecosystem that is crucial for many species.

During the dry season in December, January, and February, this flow rate is lower. The river is narrower and has a very low level of water. Still, it may have a considerable flow from base flow in groundwater sources and other smaller tributaries. Moreover, the average flow also changes along the length of the river. In the reaches closer to its source, the flow is relatively rapid owing to the steeper gradient. The rate of flow slackens as it approaches the Congo River and enters the flatter regions.

3. How to Measure Water Current of the Ubangi River?

There are quite a few ways to measure the water current of the Ubangi River.

Traditional Methods

Float Method: This is the easiest, more classic way to estimate the speed of the current in water. A buoyant object, such as a piece of wood or a bottle, is released into the river. One can get an approximation of the surface current speed by measuring how much time the float takes to travel a known distance. A problem with this method is that it is not very accurate or useful across wide rivers. These can be generated by many errors: wind, waves, and the float's shape. In addition, it provides information about only the surface current and does not give information about currents at different depths of water.

Current Meters: These have been provided by either mechanical or electronic current meters. The meters are placed in the water at a depth and record the speed of the water passing through them. They are more precise than float methods for individual points in the water column but confined to that one depth and they do not provide the current profile across the entire water column.

Advanced Method - Acoustic Doppler Current Profiler(ADCP)

These instruments are more sophisticated and efficient in the measurement taken against the water current at Ubangi River.

3.1 How do Doppler principle ADCPs work? 

An ADCP profiler relies on the principle of the Doppler effect. An ADCP emits acoustic pulses into the water. The pulses interact with the suspended particles and other substances in the water, like sediment, plankton, and small debris. Due to the movements of the water, there is a shift in frequency of the reflected acoustic signals. 

This frequency shift is measured by the ADCP meter and, by using the Doppler formula, then calculates the velocity of the water at various depths. By sending out pulses in multiple directions at different frequencies, the ADCP flow meter can create a detailed profile of the water current throughout the water column. This gives a more complete understanding of the current structure of the river than the more traditional methods that measure merely at the surface or a single point in the water column.

3.2 What is required to get high - quality Ubangi river currents measurements?

High - quality measurements of the Ubangi river currents demand highly reliable equipment. Since the climates in Africa are very harsh, with heavy rains in wet seasons, high temperatures, and floating debris that may cause damage, the measuring devices have to show their resistance against this. 

Equipment compactness-weight reduction. This will be necessary for ease of deployment, in particular in remote areas along the river or from boats. The power consumption should be low enough to enable it to operate for a considerable period of time with no frequent battery changes or external power sources. Cost-effectiveness is another key consideration, especially for large-scale or long-term measurements to monitor river dynamics. 

The use of a casing made from the said alloy in the ADCP doppler was quite an advantage. For one, the said material is resistant to corrosion that is important in a water-rich environment like Ubangi River. Continuous exposition in water, coupled with its chemicals and sediments, could readily corrode other materials. The strength and durability of the titanium alloy will also help in withstanding the physical forces exerted by the river current and any possible impacts from floating logs or other debris. This is also light in weight, which makes it easier to install and transport.

3.3 How to Choose the right equipment for current measurement?

While making the choice of the right equipment for measuring the Ubangi River, one needs to carry out the measurement requirements. 

For Horizontal Measurements:  HADCP is an ideal solution for horizontal measurements over a section of the river. It provides an overview of current flow in a horizontal plane, essential to understand the overall flow pattern within rivers. This would be very important, especially in the study of the movement of water and sediments across the river, the impact of the current on navigation, and the distribution of nutrients. 

For Vertical Profile Measurements: A vertical ADCP will be more applicable for the measurements of vertical profile current. It shall give detailed information on the speed at which water moves at greater depths, necessary for studying the stratification and mixing of the water column. This is quite crucial in understanding the distribution of oxygen and temperature in the water, among other properties and behaviors of aquatic organisms.

 Frequency Selection: Regarding the frequency selection, it may only be appropriate for quite shallow parts, up to about 70 meters, of the Ubangi River. Here, one can use a 600 kHz ADCP. For deeper parts, reaching up to about 110 meters, using a 300 kHz ADCP would be more adequate. The frequency used depends on the depth of water desired in the current profile resolution.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option with good quality, the ChinaSonar PandaADCP is a great choice. It is made of all - titanium alloy, providing durability and resistance to the Ubangi River's environment. It also offers an excellent price - performance ratio. You can visit https://china-sonar.com/ for more information.

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