ADCP's application in flood management of Amur River

1. Where does the Amur River lie?

The Amur River is one of the major rivers of East Asia. It forms part of the border between Russia and China. The river originates from the hills of the Stanovoy Range in Russia.

It flows through such varied landscapes as mountainous areas near the headwaters, extensive plains, and wetlands. The river is important to both countries, providing transportation and water for various purposes, such as agriculture, fishing, and municipal water supply.

Climatically and in terms of rainfall, the regions that the Amur River traverses are of the continental type. The winters are cold with considerable snowfall, especially in the upper reaches. Spring and summer are characterized by snowmelt and rainfall. Snowmelt from mountains and catchment, together with rainfall, is one of the main contributors to the volume of water in the river. Because of all these factors, variations of water levels are not alien to this river, and flooding might happen during heavy precipitation or when there is rapid melting of snow.

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

Snowmelt and Heavy Rainfall: The main causes of the flood are rapid snow melting in the spring season and heavy rainfall during the wet period. A lot of water from snow melting in mountainous zones and catchment areas, together with rainwater, may raise the volume of the river in a very short period. The mountainous area near its source hastens the runoff and channels a greater amount of water downstream.

Topography: There are floodplains and low-lying areas along the course of the river where water can spread out and accumulate. The gentle slopes of these plains slow down the movement of water, increasing the chances of flooding. Where many tributaries join the main course, the extra water brings in during the high-flow period adds more misery to the flood condition.

Human-Induced Changes: Deforestation of the catchment area reduces the capacity of the forest to intercept and retain the rainwater. It also leads to the erosion of the top layer of soil, and the eroded top layer deposits in the river, thereby reducing its carriage capacity. Sometimes, the construction of dams and other water-related infrastructure disrupts the natural flow and drainage pattern of water, which increases the risk of flooding in the areas.

The Acoustic Doppler Current Profiler (ADCP) can help make the flow of the Amur River more understandable and well-managed in cases of flooding.

3. How do ADCPs using the Doppler principle work?

ADCPs work according to the Doppler principle. It sends out an acoustic signal into the flowing water. Due to the flow of water, this signal encounters the mobile particles of water. While reflecting back to the ADCP current meter, the frequency of the reflected signal will be different from the original one because of the Doppler effect.

The ADCP measures the difference between the frequency of the emitted signal and the received signal. By analyzing this frequency shift, it can calculate the velocity of the water at various depths. These devices usually contain several transducers, capable of sending and receiving acoustic signals in various different directions. This provides them with the capability to create a profile of the water velocity across a section of the river.

For instance, if the water is flowing towards the ADCP current profiler, then the reflected signal will be of higher frequency compared to the emitted signal. On the other hand, if the water is flowing away from the ADCP flow meter, then the reflected signal will be of a lower frequency. Precise measurement of such frequency variations and applicable mathematical algorithms enable the ADCP meter to determine the velocity of water accurately at several points falling within its measurement range.

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

Velocity Measurement

Acoustic Doppler Current Profiler (ADCP) plays an important role during the flood events in the Amur River, determining the actual velocity of water flow. By providing continuous monitoring of the water velocities at different depths and locations, it delivers real-time data regarding the speed at which the water is moving. This becomes fundamentally necessary for the examination of flood dynamics, through which the direction and intensity of the floodwaters' movement can be predicted.

Flow Measurement Application

ADCP current profiler can also work out the flow rate of the Amur River. Measured water velocities at several points across a section of the river are combined, along with the known cross-sectional area of the river, to determine the total volume of water flowing through the section per unit time-the flow rate. This information becomes highly important in the assessment of the general volume of water in cases of flooding and also in making decisions with respect to flood control and management of water resources.

Use in Sediment Transport Research

Other than flow and velocity measurement, the ADCP flow meter  proves to be helpful in sediment transport research in the Amur River during flooding. While the water flows, it carries sediments. The ADCP profiler can detect changes in the backscattered acoustic signal caused by the presence of sediments. From such analysis, one can derive estimates of amount and movement of sediments, which is crucial to understand the long-term evolution of the riverbed and the impact of floods on the river's sedimentary environment.

5. In the case of the flood warning and risk management of the Amur River, how can the data measured by ADCP be used?

Flood Warning

Velocity and Flow Data Monitoring: The real-time velocity and flow data obtained from ADCP meter are monitored continuously. If the velocity of the measured water is higher than a certain threshold or if the flow rate increases significantly, that may indicate the approaching flood peak or a potentially flooding situation. As this forms an early warning system, the relevant authorities can take precautionary measures, like moving the residents of areas prone to flooding to higher locations or strengthening the flood defenses.

Water Level Prediction and Warning: Measured flow data correlated with historic water level data using appropriate hydrological models can give the prediction of future water levels from ADCP data. If the predicted water level is likely to exceed the warning level against flood, timely warnings can be issued to the public, enabling them to prepare for the flood.

Risk Management

Support for the Decision of Water Conservancy Project Scheduling: The accurate flow and velocity data from ADCP flow meter will help make decisions on the operation of water conservancy projects like dams and sluices. According to the measured water flow, for instance, the release from a dam helps in regulating the water level in the Amur River and further depressing the impact of floods.

Flood Disaster Assessment and Emergency Response: After a flood event, the data collected by ADCP profiler can be used to assess the severity of the flood. This includes details such as the extent of inundation, the velocity of the floodwaters, and the amount of sediment deposition. Such information is crucial for formulating emergency response plans and for carrying out post - flood reconstruction and rehabilitation work.

6. What’s needed for high - quality measurement of the Amur River currents?

For high - quality measurement of the Amur River currents, several factors need to be considered. Firstly, the equipment used should have reliable materials. The casing of the ADCP meter is of particular importance. It is recommended that the casing be made of titanium alloy. The titanium alloy applies to this, owning high strength, which lets the equipment undertake the tremendous pressure and force produced by water flow in the river. Also, it is highly resistant to corrosion, which is essential considering that the water environment of the Amur River may contain various corrosive substances.

Material reliability aside, the size and weight of the equipment should be smaller and lighter. This makes it easier to install and operate the ADCP flow meter in different locations along the river, especially in areas that are difficult to access. Low power consumption is also crucial as it allows for longer continuous operation without the need for frequent battery replacement or connection to a power source. Moreover, the cost of the equipment should be relatively low to enable large-scale measurement. It is lower in cost, which means more ADCPs can be deployed along the Amur River, providing more comprehensive and detailed data regarding flood management.

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

The equipment for current measurement in the Amur River will be chosen based on several aspects. Based on the type of measurement required, if it is for horizontal cross - section measurement, it should be a Horizontal ADCP or HADCP. In this case, if it is for vertical cross - section measurement, then a Vertical ADCP will be the appropriate choice.

Second, a suitable water depth corresponds to a particular frequency. Usually, a 600 kHz ADCP could be applied in water with a depth within 70 m. In addition, if the water depth in the Amur River is in this range and the measurement requirements are in accord, a 600 kHz ADCP is workable. For deeper waters, say above 70 m to 110 m, a 300 kHz ADCP is much more appropriate since it provides better and more accurate measurements at such depths.

To date, there are some well-known brands of ADCPs on the market, which include Teledyne RDI, Nortek, and Sontek. However, for those who are on the lookout for cost-effective options, the China Sonar ​PandaADCP is a great choice. It is made of all - titanium alloy material, which ensures its durability and reliability in the water environment. Moreover, it 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.