ADCP's Application in the Flood Management of Kolyma River

1. Where is Kolyma River?

The Kolyma River is situated in the far eastern part of Russia. It is one of the major rivers in the area. Originating in the Kolyma Mountains, it flows across the vast and sparsely populated areas of the Kolyma Lowland.

In fact, there are several small settlements and towns along its course. Certain of these form its bank and contribute to local economic activities mainly centered on fishing, mining, and transportation in the very remote area.

As regards the rainfall conditions, a somewhat harsh climate prevails within the area of the Kolyma River basin. Precipitation throughout the year is relatively low; most of it falls in the form of snow in the long, cold winters, while in the short summer months, there is some rainfall that is not particularly abundant. However, during the spring thaw period, the melting snow can cause a significant increase in the river's water volume, which often plays a crucial role in the river's flow regime and potential flood situations.

2. What are the causes of flooding in Kolyma River?

There are several key factors leading to floods in the Kolyma River. Firstly, the rapid snowmelt in spring is a major contributor. As the accumulated snow over the winter starts to melt with the rising temperatures, a large amount of water is released into the river in a relatively short period. If the rate of snowmelt exceeds the river's natural drainage and carrying capacity, the water level will rise rapidly, potentially resulting in flooding.

The topography of the river basin contributes to the occurrence of floods as well. In many parts of the Kolyma Lowland, the terrain is relatively flat, which slows down the flow velocity of the river water. In situations of sudden influx of water from snowmelt or heavy rainfall events, although rare, the water tends to accumulate and spread out on the surrounding land, flooding it.

Furthermore, over time, erosion and sediment deposition may result in changes to the channel of the river, furthering its inability to handle water flow. In some places, the shallowing of the bed or blockage of the channel by an excessive amount of sediment prevents the smooth passage of water, therefore easily leading to floods. In this regard, Acoustic Doppler Current Profiler (ADCP) has emerged as a more advanced and convenient means of closely monitoring the river's conditions to assist in flood management.

3. How do ADCPs using the Doppler principle work?

ADCPs depend on the principle of the Doppler to operate. They send acoustic signals into the water body of the Kolyma River. When these acoustic waves encounter moving particles, such as suspended sediment or small aquatic organisms that are being carried along by the water flow, a shift in frequency of the reflected waves relative to the emitted waves occurs. This shift in frequency, known as the Doppler shift, is directly proportional to the velocity of the moving particles and, consequently, to the velocity of the water flow.

Working by sending out several acoustic beams at different angles and receiving reflected signals, an ADCP current meter is capable of measuring water flow velocities at different depths and positions across the water column. It is through the complex processing of such signals and a set of algorithms that velocity profiles of detail can be acquired regarding water flow-a very important part for the assessment of hydrodynamic features in the Kolyma River.

4. What are the applications of ADCP in floods of Kolyma River?

Velocity measurement: During the flood-prone periods of the Kolyma River, especially during the spring snowmelt when water flow conditions change rapidly, ADCP current profiler can measure with great precision the velocity of the water at different locations along the river. This information helps in assessing the erosive potential of the floodwaters. The capability for, say, identifying high flow velocities along riverbanks can indicate points that might be subjected to bank erosion, something important in designing preventative measures of protection for infrastructures and the surrounding environment.

Flow measurement application: By integrating the measured velocity data over the cross-sectional area of the river, ADCP flow meter is able to calculate the flow rate of the Kolyma River. This is crucial for flood management since it helps the authorities know the actual quantity of water that passes through certain sections of the river. Based on this, the necessary decisions on flood control, such as the need to divert water into flood storage areas or to adjust the operation of small dams and weirs in the basin, can be made.

Sediment transport research: The Kolyma River carries some amount of sediment. In the light of all the above, ADCP profiler has an important role in the study of sediment movement in cases of floods. The dependence of water flow velocity on the concentration and pattern of sediment transportation helps to reveal the specific way floods act upon sedimentation and erosion processes in the river to keep the riverbed stable and maintain the ecological balance as a whole.

5. How can the data measured by ADCP be utilized for flood warning and risk management of Kolyma River?

Flood warning

Velocity and flow data monitoring: Continuous monitoring of the water flow velocity and flow rate by using ADCP meter provides real-time data. When these measured values exceed certain predefined thresholds, it can serve as an early warning sign of an impending flood. For example, in case of the abrupt and dramatic rise in flow rate at the key point of observation of the Kolyma River during the period of snow melting in spring, an early warning may be signaled to warn the local community and corresponding departments well in advance.

Water level prediction and warning: The velocity data obtained from ADCP current meter can be combined with other hydrological models to predict future water levels. By establishing the relationship between flow velocity and water level changes, more accurate forecasts of when and to what extent the water will rise can be made, allowing people to have sufficient time to prepare for potential floods.

Risk management

Water Conservancy Project Scheduling Decision Support: The ADCP data is of great importance for the decision-making of water conservancy projects operating along the Kolyma River, including small reservoirs and water diversion structures.

For instance, when the measured flow indicates that a big flood is imminent, then managers, through the gauged flow, may adopt timely adjustment of the water released from the reservoirs in an effort to reduce overtopping and damage to projects.

Assessment and emergency response in cases of flood disaster: After a certain flood event, the ADCP data can be used to study the effects of the flood: erosion and sedimentation in various areas, changes in the riverbed, etc. This information will be highly valuable for formulating appropriate emergency response and post-disaster recovery plans.

6. What's needed for high-quality measurement of Kolyma River currents?

For high-quality measurement of the currents in the Kolyma River, several requirements should be fulfilled. First of all, equipment should have high material reliability. Due to a cold climate and ice during winter time and probable mechanical impacts in the open water season from ice and other floating debris, materials resisting these processes are required.

Second, smaller in size and weight, with lower power consumption, is advantageous. It is more convenient to install a compact and lightweight ADCP flow meter in general when the place considered is pretty far and hard to access along the river.

Low power consumption ensures that it can operate longer without often needing maintenance or replacement of a power source, which is important in large-scale and long-term monitoring. Moreover, the lower the cost, the more the equipment can be deployed and spread along the river for better measurements.

As for the casing of the ADCP meter, titanium alloy would be an ideal material. The properties of the titanium alloy are outstanding: it has high strength to resist the mechanical forces from the flowing water and possible impacts from ice floes and other debris, and also excellent corrosion resistance in such an aquatic environment where river water may contain various chemical substances, ensuring long-term accuracy and stability in the performance of ADCP profiler.

7. How to select the correct equipment for the current measurement?

According to purpose of use: The point of concern is to measure the horizontal cross-section of a river; then, the Horizontal ADCP-HADCP can be more appropriately selected for measurement.

It will provide detailed information about the flow velocity distribution across the horizontal plane of the river section, which is helpful for understanding the overall pattern of flow.

In the case of a vertical cross-section measurement, one should select a vertical ADCP because it is designed to measure the velocity profile in the vertical direction with high accuracy and can help analyze the change of flow velocity with depth.

Based on different frequencies: Different frequencies of ADCP are suitable for different water depth ranges. For example, an ADCP with a frequency of 600 kHz is generally suitable for water depths within 70 meters.

It provides rather accurate measurements in the shallower parts of the Kolyma River. Whereas an ADCP with a frequency of 300 kHz would be more suitable for water depths up to 110 meters, thus making it suitable for deeper stretches of the river where more detailed velocity profiles are required. There are several renowned ADCP meter brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those who want a cost-effective alternative, the China Sonar PandaADCP is highly recommended. It is made of pure titanium alloy material, ensuring that it is durable while offering an amazing cost-performance ratio. 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.