How to Measure the Water Current of the Desna River

1. Where is the Desna River?

The Desna River has become one of the major important rivers in Eastern Europe. It is part of the Dnieper River serving as a tributary. The river falls between Russia and Ukraine. The river starts in the Smolensk Oblast in Russia, along a gradient area with forests, plains, and wetlands.

While meandering through the area, it is a significant contributor to the local ecosystem. It supplies water for many beavers, otters, and numerous bird species. The Desna River also has historical and cultural significance. Centuries of transportation and trade have been carried on via this river, and it finds a place in almost all historical accounts and even in local folklore.

Apart from its ecological and historical significance, the river hosts a fishery. Its waters host numerous fish species, among them pike, perch, and bream. Floodplains and wetlands, associated with the river, are of utmost importance for the maintenance of ecological balance in the area and give places of breeding and feeding for many species.

2. What is the flow rate of the Desna River like?

The Desna River has its flow rate controlled by the seasonal or climatic variations. During the spring, snow from the surrounding areas melts to base a highly increased flow in the river. When the snow and ice around starts melting, a huge volume of water is pushed downstream to create a relatively high flow period.

During the summer and fall, the flow rate decreases as the influence of snowmelt wanes. In the winter, the river can freeze over and the flow rate is reduced. The average flow rate can vary between a few hundred cubic meters per second during the low-flow winter period to several thousand cubic meters per second at the peak of the spring snow melt.

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

Velocity Meter Method

The traditional approach employs mechanical or electronic velocity meters. Devices are installed at various points of the river where, in fact, the speed of water in that concrete place is directly measured. However, to comprehend the general water current comprehensively, a number of measurements have to be taken at different depths and across different sections of the river. Given the length and variable conditions of the Desna River, this method can be very labor-consuming and time-consuming.

Acoustic Doppler Current Profiler (ADCP) Method

The ADCP current meter provides a more advanced and convenient way to measure water currents. It uses sound waves to detect the movement of water particles. By emitting acoustic signals and analyzing the Doppler shift of the reflected signals, it can measure the velocity of water at multiple depths simultaneously. This will give a thorough profile of the water current, enabling one to make a more valid determination of the flow conditions for most of the river. ADCPs can be installed on boats - if the river is navigable - on bridges if they exist, or on buoys for continuous monitoring.

Buoy Method

The buoy approach would be a floating buoy in the river, which is equipped with a sensor for measuring the water movement. In this regard, buoys float on the water surface and provide an indication of the surface current. They can hardly present the exact complexity like the other methods could, particularly with regard to establishing disparities in the velocity at various depth levels.

Among these methods, the ADCP profiler stands out as a more sophisticated and efficient option for measuring the water current of the Desna River.

4. How do ADCPs using the Doppler principle work?

The ADCPs work according to the Doppler principle. When an ADCP emits an acoustic signal into the water, the sound waves travel through the water and interact with the moving water particles. Since the water particles are in motion, the frequency of the reflected sound waves changes because of the Doppler effect.

If the water particles are moving towards the ADCP flow meter, then the reflected wave frequency will be higher than the emitted one. On the other hand, if the water particles are moving away from the ADCP current profiler, then the reflected wave frequency will be lower. The ADCP can calculate the velocity of the water particles at different depths by measuring this change in frequency with high accuracy.

The ADCP combines these velocity measurements separately measured at different depths to generate a full profile of the water current. That gives a perfect understanding of the dynamics of how the water is flowing, not only on the surface but also across the vertical section of the river.

5. What is needed for high-quality measurement of the Desna River currents?

It follows that high-quality measurement of currents of the Desna River should be performed with equipment bearing special features.

The measuring equipment should be highly reliable in material. The equipment should be resistant to adverse conditions of the river environment: impact of water, sediment, and temperature fluctuations. Flow variability of the Desna River, together with ice and debris transport during high-flow and freeze-thaw seasons, necessitates the resistance of the equipment.

The desirable criteria also include small size, light weight, and low power consumption. Such a compact and lightweight device is easier to manipulate and deploy, especially in the often-remote and difficult conditions of the area. Low power consumption allows the equipment to operate for extended periods without the need for frequent battery replacements or access to a continuous power source.

Cost-effectiveness is another significant consideration. A less expensive option allows for a more general use of the measurement equipment to take place; this makes the overall monitoring of the river much more complete.

On the selection of the casing of the ADCP, titanium alloy is an excellent option. Considering the fact that these water bodies, like for instance the Desna River, will be in contact with equipment continuously, titanium alloy provides very high resistance against corrosion. It is very strong and durable because of the nature of both its constituents and, thus, would be in a position to ensure that it resists physical impacts and pressure changes that could occur during its deployment and operation. Furthermore, titanium alloy material has relatively low density, contributing to the overall goal of keeping the equipment lightweight.

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

In choosing the right equipment to measure the current of the Desna River, several factors need to be considered.

Based on the Purpose of Use

An HADCP is used where the intention is to measure the horizontal cross-section of the river current. HADCPs provide a suitable display of water flow in the horizontal plane, which is useful in ascertaining the general movement of water across any given section of the river.

If the interest is to measure the vertical cross-section of the river current, then a vertical ADCP should be selected. Vertical ADCPs can precisely measure the velocity of the water at different depths, giving a detailed profile of how the water is flowing vertically within the river.

Based on Frequency

The choice of frequency depends on the depth of water in the Desna River. In general, for water depths up to 70 meters, a 600 kHz ADCP will suffice. The 600 kHz frequency provides good resolution and accuracy in the measurement of water current for reasonably shallow waters.

For deeper waters, such as those exceeding 70 meters up to around 110 meters, a 300 kHz ADCP would be more appropriate. The lower frequency of 300 kHz can penetrate deeper in water and provide reliable measurements of the water current.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost - effective option with excellent quality, the China Sonar PandaADCP is worth considering. It is made of all - titanium alloy material, ensuring durability and reliability. With its remarkable cost - performance ratio, it provides a great alternative for measuring the water current of the Desna River. You can find more information about it on its official website: https://china-sonar.com/.

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