How to measure the water current of the Narew River?

1. Where is the Narew River?

The Narew is a major river in northeastern Poland and partly in Belarus. The river runs its course through the wetlands, meadows, and forests-all blended together in harmony.

Within Poland, the course of the Narew runs through areas highly valued for their natural environments and historical features. Large differences in a water level can be noticed on its banks, on which exceptional flora and fauna develop. The wetlands along the course of Narew River feature rich, water-loving vegetation; a habitat for reeds, different water lilies varieties are all common here. Besides giving food and nesting place to different bird species, among others, herons, and cranes, this also shelters many bird species during hibernal and migrational seasons. Long-standing relations exist with communities locally situated along this river. Narew River has been used for catching fish-a source of livelihood and life for so many. It also divides some regions as a border and has influenced the local settlement pattern and cultures.

2. What is the Flow rate of the Narew River?

The flow rate of the Narew River varies on a seasonal basis. Throughout the spring, the river swells due to the snowmelt from upstream and increased rainfall. The water rushes downstream with a comparatively high velocity, and the discharge is much higher compared to that in other seasons. Powerful flow during this period can shape the riverbanks to a certain extent and influence the sediment distribution.

In the summer and autumn, the flow rate becomes more stable. The average flow velocity might range from [provide an estimated range, for example, 0.3 - 1.0 meters per second], and the discharge could be around [mention an estimated volume such as 10 - 50 cubic meters per second]. In winter, the river freezes partially, depending on the cold, and the flow rate under the ice is much smaller. When the ice melts in spring, the cycle of changing flow rates begins anew.

3. How to measure water current of Narew River?

There is a possibility of measuring the water current of the Narew River by the following methods:

Velocimeter method: This is a more orthodox technique that involves the use of a velocimeter, either of a mechanical or electrical type. These instruments are then strategically placed at various points along and into the river. The current flow at these points can be directly measured by these instruments, therefore creating a basic idea of the current. However, this approach is too time-consuming and labor-intensive for a detailed mapping of the current profile across different parts of the river.

Acoustic Doppler Current Profiler (ADCP) method: ADCP current meter is more efficient and an advanced technique. It works by emitting acoustic signals into the water column and analyzing the Doppler shift of the reflected waves. This allows it to measure the velocity of water at multiple depths simultaneously. Compared with the velocimeter method, ADCP current profiler gives a wider and more detailed view of the flow conditions in the river in less time.

Buoy method: This method involves deploying buoys with sensors or tracking devices on the surface of the Narew River. By observing the movement of the buoys over time, an estimate of the surface current speed and direction can be derived. However, this method mainly focuses on the surface flow and may not accurately represent the conditions at deeper depths.

Among these, the ADCP flow meter is currently considered a more advanced and convenient way to measure the water current of the Narew River due to its ability to provide detailed, multi-depth data with relatively less effort.

4. How do ADCPs using the Doppler principle work?

The principle on which ADCPs operate is the Doppler principle. They emit acoustic pulses at a known frequency into the water. When these sound waves interact with moving particles in the water, such as sediment particles or small organisms, the frequency of the reflected waves changes. This change is known as the Doppler shift.

The frequency is higher if the particles are moving towards the ADCP meter and lower if they are moving away. Precise measurement of this frequency shift, coupled with knowledge of the angle the acoustic signals were both transmitted and received, allows the ADCP to determine how fast the water is moving at various depths. Multiple transducers on the ADCP profiler are usually mounted in different orientations to measure the flow velocity in different directions, including both horizontal and vertical components. This allows the construction of a detailed profile of the water current within the river.

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

The equipment for high-quality measurement of the Narew River currents has to feature a few qualities. First, the materials used in constructing the measuring devices need to be reliable. The equipment also needs to be able to deal with often-harsh conditions within the river. This is inclusive of potential impacts from floating debris, as well as variations in water temperature and quality.

Equipment in these stations should be of small size, light weight, and with low power consumption. The small-sized equipment allows for compact designs that can be deployed or retrieved with ease, particularly because this region has parts with complicated access to the river. Low power consumption allows this equipment to run for more hours without changing batteries or needing a substitute for an external power supply.

Another important factor to consider has to do with cost, especially when making large-scale measurements. In regard to ADCPs, titanium alloy is a very good material for the casing. Titanium alloy has many advantages. Firstly, it has excellent resistance to corrosion, which provides the ability to withstand exposure to the river water over a long period of time without significant damage. It is also strong and durable, able to withstand mechanical stresses such as those caused by water currents and accidental impacts. In addition, it is lighter compared to most metals, which makes it an appropriate material for equipment applied in water current measurement.

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

The following can be considered in choosing the right equipment for measuring the current of the Narew River. The Horizontal ADCP (HADCP) is a fit for taking the horizontal cross-section in measuring, while the flow of every characteristic in a horizontal plane is accurately captured. This will apply to the Horizontal ADCP. The Vertical ADCP will more appropriately apply to the case of measuring the vertical cross-section as it gives more comprehensive detail on the flow at different depths along a vertical line.

The second one refers to different frequencies of ADCPs suited for different water depths; an example could be that ADCP, with a frequency of 600 kHz, which turns out to be well suited in water depth within 70 meters. It provides a clear and accurate measurement of the relatively shallow part of the Narew River. Meanwhile, an ADCP with a frequency of 300 kHz is more applicable for water depths up to 110 meters, effectively allowing measurements in the deeper parts of the river.

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.