How to measure water current of Lukenie River?

1. Where is Lukenie River?

The Lukenie River is one of the major rivers of the Democratic Republic of the Congo. It cuts across the heart of the central region, amidst a landscape of lush rainforests and expanses of savannah grasslands.

It passes various small villages and communities while tracing its course. These local settlements are inextricably linked with the river. The Lukenie River is an important source of drinking water, water for cooking, and other domestic uses among the communities that live nearby. It serves as an important transportation conduit, especially during wet months of the year when the volume of water increases and allows the passage of small boats. The riverbanks are lined with a diverse array of vegetation, from tall trees that provide shade and habitat for various wildlife species to thick bushes that are home to smaller animals and insects.

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

The flow rate of the Lukenie River varies considerably depending on the season. In the rainy season, normally beginning from [Mention the specific months of the wet season in the region], a lot of water comes in with heavy rainfall in its catchment area. The river swells, and the flow becomes quite powerful, with the water rushing downstream at a relatively high velocity. This is a time when the discharge can be quite high to the extent that the river is full and bubbly.

During the dry season, however, the flow rate significantly slows down. The water levels go down, and the river might become narrow in some areas. The average flow velocity during the dry season could be in the range of [provide a range, such as 0.2-0.6 meters per second], while the discharge can be as low as [give an estimated low-flow discharge in cubic meters per second]. These variations in flow rate seriously affect the local ecosystems and the livelihoods of communities depending on the river.

3. How to measure water current of Lukenie River?

There are several methods that can be used to measure the water current of the Lukenie River.

Velocimeter method: This is the traditional method using mechanical or electrical velocimeters. Operators lower these instruments into the river at various depths and locations along its length, where they can directly measure the speed of the water flow. This, however is a cumbersome procedure, involving lengthy time and labor, since many a number of measurements must be done at several positions to gain an adequate data on the current profile of the river.

The ADCP method represents modernity and high efficiency because it operates by sending acoustic signals to the water column and taking into consideration the Doppler shift of the reflected waves back to determine the velocity of a mass of water at the same time at different levels that gives detailed and accurate pictures over the flow conditions of a river, much quicker in comparison with the velocimeter method.

Buoy method: In this method, the buoys with sensors or tracking devices are left on the Lukenie River's surface. By observing the time-related movement of the buoys, an estimate about the speed and direction of surface current could be obtained. It generally gives information about the flow of the surface, without an accurate representation of what conditions are at the further bottom of the river.

Of all these methods, the ADCP meter is currently the more advanced and convenient means of measuring the water current of the Lukenie River insofar as it provides detailed multi-depth data with relatively less effort.

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

The working principle of ADCPs is based on the Doppler principle. ADCPs emit acoustic pulses of a certain frequency into the water. As these sound waves come across moving particles in the water-sediment particles or small organisms-the frequency of the reflected waves changes, which is generally referred to as the Doppler shift. When the particles are moving towards the ADCP flow meter, the reflected frequency is higher than the emitted one; when they are moving away, it is lower.

By precisely measuring this frequency shift, and considering the angle at which the acoustic signals were emitted and received, the ADCP current profiler can calculate the velocity of the water at different depths. Several transducers on the ADCP are usually mounted in different orientations to measure the flow velocity in different directions, including both horizontal and vertical components. This enables the development of a full profile of the current of the water in the river, thereby helping to get the speed and direction of flow of water at different levels of depth.

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

The measurements of the currents of the Lukenie River with high quality require some facts about the measuring equipment, first of all, reliability of the materials the equipment is made of is crucial. These devices will have to be able to overcome the harsh and sometimes unpredictable river environment in the Democratic Republic of Congo. Among other things, this includes withstanding potential impacts from floating debris, variations in water temperature and quality, and strong water currents during the wet season.

Second, the size should be small, with light weight and low power consumption. A compact design makes it easier to transport and deploy the equipment to the various locations along the river, especially considering that some areas may be difficult to access due to the dense rainforest surroundings. Low power consumption ensures that the equipment can operate for extended periods without needing frequent battery replacements or external power sources.

Cost is also another critical factor, as it allows for extensive measurement campaigns. In ADCPs, the casing material could be of titanium alloy. The usage of titanium alloy has several advantages. It has excellent resistance to corrosion, hence can resist deterioration from the river water over long exposure. It is also strong and durable to resist mechanical stresses such as those from water currents and impacts due to accidents. Besides this, despite being strong, it is light compared to a number of other metals, and for that reason, it forms a very good material in making equipment to be used in water current measurement.

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

When choosing the right equipment for measuring the current of the Lukenie River, there are several aspects to consider. Firstly, depending on the usage purpose, if the aim is to measure the horizontal cross-section of the river's flow, then HADCP is preferred. This is specifically designed to precisely capture the flow characteristics in the horizontal plane. On the other hand, for vertical cross-section measurements, the Vertical ADCP current meter is more suitable as it focuses on providing detailed information about the flow at different depths along a vertical line.

In addition, the different frequencies of ADCPs will be suitable for different water depths. For example, an ADCP with a frequency of 600 kHz is quite suitable for a water depth within 70 meters. It could provide clear and accurate measurement in the relatively shallower part of the Lukenie River. An ADCP with a frequency of 300 kHz is more suitable for water depths up to 110 meters and enables the effective measurement in deeper parts of the river.

There are several known brands in the market, including Teledyne RDI, Nortek, and Sontek. However, for those seeking a budget-friendly yet quality option, they should look no further than the China Sonar PandaADCP. Constructed with fully titanium alloy material, it does not only promise durability and reliability but is also greatly cost-effective. You can learn more about it from its official website: https://china-sonar.com/.

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