ADCP Applied in the Flood Management of the Stony Tunguska River

1. Where is Stony Tunguska River?

Stony Tunguska River is a river located in Siberia, Russia. It's a main tributary of Yenisei River and flows across an enormous wild area dominated by taiga landscape.

Geographically, it passes through areas with a relatively cold climate. The course of the river is enveloped by a rich wilderness that has a great variety of wildlife, including bears, wolves, and several species of fish. Along its banks are small settlements of indigenous peoples who depend on the river for fishing and other aspects of their traditional livelihoods.

From the point of view of rainfall, the Stony Tunguska River Basin is a continental climate. In the winter, there is heavy snowfall. In summer, the rainfall is relatively moderate. The snowmelt in spring, along with the summer rainfall, is the main contributor to the river's water volume.

2. What are the Reasons for Floods in Stony Tunguska River?

Snowmelt and Heavy Rainfall: Most flood episodes in the Stony Tunguska River were determined to take place under conditions of snowmelt combined with heavy rainfall. In spring, sudden breaking of the thick snow cover can cause a sudden surge in the water level. Intense summer rain showers can also contribute to sudden volume increases. Put these two factors together, or in fairly rapid sequence, and the river's capacity can easily be exceeded with resultant flooding.

Topography and Drainage: The river runs through some relatively flat floodplains and with some natural constrictions. The flat areas slow the flow of water, where it spreads out and flooding into the surrounding areas easily occurs. The constrictions have the potential to delay the regular flow of water and result in water building up and raising the upstream water level. The improper drainage of the area resulting from the frozen ground in spring or saturated soil as a result of heavy rainfall may worsen the situation.

Vegetation and Land Cover Changes: Man-induced or natural alterations to vegetation cover can result in variation in the river's water balance. For example, forest fires or logging activities in the taiga forest reduce the capacity of the land to absorb more water. This results in more surface runoff, eventually contributing to higher levels of water and causing floods. In this regard, the Acoustic Doppler Current Profiler presents a more sophisticated and effective solution for measurement regarding flood-related data compared to conventional techniques.

3. How Do ADCPs Using the Doppler Principle Work?

The ADCPs work on the principle of the Doppler. They send acoustic signals into the water. These acoustic waves interact with moving particles in the water, such as sediment, debris, or simply water parcels with different velocities; the frequency of the reflected signals from the emitted signals changes by the Doppler effect.

The ADCP measures these frequency shifts and, using the known speed of sound in water and the angles of the emitted and received signals, calculates the velocity of the water at different depths. Multiple transducers in the ADCP flow meter are arranged to measure velocity components in different directions. By integrating these velocity measurements over different depths and cross-sectional areas of the river, the flow rate and other important hydrological parameters can be determined.

4. What are the Applications of ADCP in Floods of Stony Tunguska River?

Velocity Measurement: ADCP current profiler will be able to measure the actual velocity of water flow in the Stony Tunguska River at various locations and depths. This information is very valuable during flood events in understanding the dynamics of the flood. It helps in identifying areas where the flow is rapid and could be dangerous for the riverbanks, bridges if any, and the local settlements. It also allows for monitoring how the flow velocity changes with time as the flood progresses.

Flow Rate Measurement Application: Combining the measured velocity data with the cross-sectional area of the river, ADCP current meter can estimate the flow rate. This is crucial in predicting the amount of water that would pass through various sections during a flood. It helps to anticipate the flood peak and its impact downstream, important for flood management strategies.

Sediment Transport Studies: During flooding, a large quantity of sediment load is carried by floodwaters in the Stony Tunguska River. ADCP flow meter will analyze sediment movements based on echoes that acoustic signals return to their origin after interference with moving sediment particles. Further, this helps to obtain necessary insights into the flood impacts on the riverbed evolution concerning sediment depositions and erosions for sustaining stability of the river channel and an ecosystem as a whole.

5. How may data measured by the ADCP be used to help provide a flood warning for risk management in the Stony Tunguska River?

Flooding Warning

Velocity and Flow Rate Data Monitoring: ADCP profiler continuously monitors the velocity and flow rate data. Through this, early detection of abnormal increases in these parameters is allowed. When the flow rate approaches or exceeds these critical values, it would then indicate that the flood peak is approaching. Thus, on-time warnings could be issued to the local people and the concerned authorities.

Water Level Prediction and Warning: By correlating the measured flow rate and velocity data with historical water level records, models can be developed to predict future water level changes. This helps in providing advance warnings about potential inundation areas and the height of the floodwaters.

Risk Management

Water Conservancy Project Scheduling Decision Support: ADCP data can support decisions on the operation of water conservancy projects like small dams or reservoirs, if any, along the Stony Tunguska River. For instance, it can support the timing and volume of water release from the reservoir to reduce the impact of floods downstream.

Flood Disaster Assessment and Emergency Response: When the flood event has taken place, ADCP-measured data may be used in the evaluation of the flood magnitude regarding the extension of flooded areas and the flow characteristics developed in the time of flooding. These are helpful in the course of guiding emergency response in the instance of distributing relief resources or in planning post-flood recovery work.

6. What is required to have a good measurement of stony Tunguska river currents?

The equipment in this kind of measurement requires reliable materials for high-quality measurement of the Stony Tunguska River currents. First, the casing should withstand impacts from the floating debris-maybe more in case of a flood and corrosion caused by water, which, depending on the specific chemical content of the substances dissolved, will be connected with its surroundings. Therefore, in such extreme conditions as those prevailing between winter and summer, it is hard to overestimate the importance of temperature effects.

It is envisaged that the equipment should be of a size that is small enough to be installed and deployed at different locations in the river, more so at areas that are not accessible due to the nature of the place. Light in weight also for ease of transportation and installation. The power consumption should be low to allow for continuous operation for long periods without changing batteries or other high-energy power sources. It has to be cost-effective enough to deploy on a large scale for extensive monitoring.

The ADCP current meter casing is best made up of titanium alloy. The outstanding advantages of the choice of titanium alloy include good resistance to corrosion, which will, in turn, put it through the test of long-term exposure in river water. The strength-to-weight ratio is also so high that while the material contributes enough strength, the weight is kept at reasonable levels with this material, thus granting the equipment performance stability at all environmental conditions in the different parts of the Stony Tunguska River Basin.

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

There are a number of considerations when choosing the right equipment for current measurement in the Stony Tunguska River. The HADCP should be chosen first for its horizontal cross-section measurement in view of the purposes. It will provide more reliable readings of flow velocity and any other parameters across the section, horizontally. On the other hand, when it comes to vertical section measurements, a Vertical ADCP is better because it gathers greater detail on the velocity profiles vertically down the axis.

According to the actual water depth, different frequencies should be chosen. For the water depth within 70 meters, a 600 kHz frequency ADCP flow meter is usually appropriate because it can provide relatively accurate measurement results within this depth. When working at more profound water areas of up to 110 meters, the 300-kHz frequency is suitable; the ADCP will ensure penetration to such depths is realized with reliable data delivery.

There are various ADCP brands available in the market, such as Teledyne RDI, Nortek, and Sontek. However, it is worth highlighting a high-quality and cost-effective Chinese ADCP brand-China Sonar PandaADCP. It is made of all-titanium alloy material, ensuring excellent performance and durability. You can find more information on its website: (https://china-sonar.com/)

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