How to Measure Water Current of Kotuy River?

1. Where is Kotuy River?

The Kotuy River probably is one of less - well - known rivers. It should be somewhere in a really remote place, perhaps in some polar or sub - polar region.

If it is situated in a polar region, then tundra landscapes with low - lying vegetation such as mosses and lichens will surround it. The banks of the river might also be frequented by typical arctic wildlife, including reindeer, arctic foxes, and several types of migratory birds. The water of the Kotuy River could be an important resource for these animals, providing drinking water and a habitat for fish and other aquatic organisms.

In such a cold environment, the flow of the river could be influenced by the occurrence of ice. It would either freeze totally in winter or have much ice that could alter its flow dynamics. During summer, with the melting of ice, the flow rate and volume can vary considerably.

2. What is the Nature of the Flow Rate of the Kotuy River?

In this respect, the discharge of the Kotuy River may strongly be controlled by a seasonal cycle, especially within polar or cold-climate conditions.

In spring and summer, when the snow and ice in the surrounding areas are melting, the river receives an immense inflow of water. The water level goes up, and the flow can be very strong. This inflow of meltwater brings with it a lot of sediment and nutrients, which can have an impact on the riverbed and the general ecological balance of the river.

During the fall and winter, the flow rate is lowered. The river may freeze over, and the water movement beneath the ice is much slower. There could, however, be some sub-ice flow due to factors such as groundwater seepage and pressure differentials. The amount of ice that forms and how it restricts the water's movement also determines the flow rate during these colder months.

3. How to Find the Water Current of Kotuy River?

There are various techniques for measuring the water current of the Kotuy River:

Velocity Meter Method: The traditional technique is by using a velocity meter. These may be mechanical or electrical. Mechanical velocity meters normally contain some rotating element that is driven by the water flow. The rate of rotation is proportional to the water velocity. These meters must be installed at more precise points in the river, usually attached to bridges where available, piers, or other fixed structures. However, in a distant area like where the Kotuy River might be located, setting up and maintaining the meters could be challenging since access is difficult and weather conditions could be harsh.

Acoustic Doppler Current Profiler (ADCP) Method: ADCP current meter is one of the advanced and quick methods for the measurement of water current. It can measure the velocity of water at several points within a water column at the same time using acoustic waves. By emitting sound pulses and analyzing the Doppler shift of the reflected signals, it can give a very detailed profile of the water current from the surface to the riverbed. ADCPs can be mounted on boats (if the river is navigable during the appropriate season) or fixed structures near the river. This method allows for a more accurate and comprehensive view of the flow patterns compared to the velocity meter method.

Buoy Method: Buoys equipped with sensors can be deployed on the surface of the Kotuy River. These buoys would measure the surface current while moving with the flow. The resulting data from this method includes directions and speeds of the surface movement. However, this method is mainly confined to the surface layer and is not expected to yield detailed information on flow at deeper levels in the river.

Out of all these, the ADCP current profiler method has gained much favour nowadays because it gives detailed, extensive data with relatively lesser effort and in a quicker time span.

4. How do the Doppler Principle ADCPs work?

The ADCPs rely on the Doppler principle. An ADCP flow meter used to measure the current of the Kotuy River sends out acoustic pulses into the water. The acoustic pulses interact with particles in the water, such as sediment particles, small aquatic organisms, or other suspended matter.

When these particles are moving, due to the Doppler effect, the frequency of the reflected sound waves change. If the particles move toward the ADCP meter, then the frequency of the reflected waves is higher than that emitted, and vice-versa if they are going away. By precisely measuring this shift in frequency and with advanced algorithms, the ADCP estimates the velocity of the water at different points within the range it measures.

Apart from the velocity, ADCPs are also able to find out the direction of flow by analysis of phase shifts of the reflected signals coming from different directions. Therefore, the profile of velocities, which demonstrates the water flow in a real-time regime at every depth and section of the river, can be built with great accuracy.

5. What is required to get a high-quality measurement of currents in the Kotuy River?

For high-quality measurements of the currents of the Kotuy River, the equipment should have specific features.

The materials of the equipment should be reliable to withstand the harsh environmental conditions. In a cold-climate setting, the equipment needs to be able to tolerate freezing temperatures, ice impacts, and possible submersion in icy water. A small size and light weight are beneficial, especially for ease of deployment and retrieval in a remote area with limited access.

It is also very important to have low power consumption. Due to the probable remoting of the Kotuy River, equipment that can keep running for a long period with little power consumption rate is required for continuous data collection and reliability. Another important aspect is cost-effectiveness. Affordable equipment without a compromise in quality is needed in order to perform comprehensive measurements of the river.

When it concerns the casing of the ADCP, titanium alloy is indeed an excellent choice. Basically, titanium alloy has a very good corrosion-resistant ability, which is essential to be used in the instrument since it will always have contact with the river water. It also has excellent strength-to-weight ratio so that it can provide a hard case while keeping the whole weight of the equipment relatively small. This helps in the protection of the internal components and ease of handling during deployment and retrieval.

6. How to Choose the Right Equipment for Current Measurement?

When choosing the right equipment for current measurement of the Kotuy River, two main factors should be considered.

Based on the usage purpose, for horizontal cross-section measurements, the horizontal ADCP (HADCP) is a suitable choice. It will measure the flow velocity across a horizontal plane and hence yields substantial information on the lateral movement of water within the river. The vertical ADCP is more appropriate for vertical cross-section measurements since it concerns the flow velocity from surface to riverbed along a vertical line, useful for understanding the flow characteristics in the vertical direction.

Different frequencies are fit for different water depths on grounds of frequency. For example, an ADCP 600 kHz is well-suited for water depths within 70 m. Hence, it can provide better data in relatively shallow areas of the Kotuy River. Meanwhile, an ADCP of frequency 300 kHz would suit a water depth of 110 m or less. Therefore, for deeper areas where flow features may be intricate, an ADCP with higher frequencies could apply.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. Additionally, a Chinese ADCP brand, China Sonar PandaADCP, is highly recommended. It has a casing made entirely of titanium alloy, which provides excellent durability and corrosion resistance. It also offers an incredible cost-performance ratio. 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.