ADCP's Application in Flood Management of Aldan River

1. Where is Aldan River?

The Aldan River is located in the frigid and expansive Siberian region of Russia. It serves as the largest right-bank tributary of the Lena River. Originating from the northern slopes of the Stanovoy Range, it winds its way northward across the Sakha Republic (Yakutia).

This river passes through several small settlements and towns that rely on it for water supply, fishing, and transportation during the ice-free season. Prominent among them are areas where indigenous communities have thrived for generations, maintaining their unique cultural traditions tied to the river. The climate in the Aldan River basin is extreme, with long and bitterly cold winters, and short, cool summers. Precipitation is relatively scarce throughout the year, mainly falling as snow during the winter months. In spring, the melting snow plays a crucial role in swelling the river’s volume, leading to the primary flow peak.

2. What are the Reasons for Floods in Aldan River?

Snowmelt: Given the Siberian climate, heavy snow accumulates in the Aldan River’s catchment area during winter. As temperatures start to rise in spring, the snowpack melts rapidly, discharging a large volume of water into the river. If the rate of snowmelt is too swift and exceeds the river’s natural drainage capacity, water levels can surge, resulting in floods. For instance, an unusually warm spring or a thick snowpack from the previous winter can trigger this scenario.

Ice Jams: During the spring thaw, ice floes break up and start moving downstream. In some cases, they can pile up and form ice jams, obstructing the normal flow of water. This causes water to back up and inundate the surrounding areas, leading to flood conditions. The relatively flat sections of the river course exacerbate this issue as the water has less kinetic energy to break through the ice blockages.

Rainfall Events: Although annual rainfall is not high, intense and sudden rainstorms during the summer can contribute to flooding. When heavy rain falls over a short period, and the ground is already saturated from previous snowmelt or light rain, the excess water quickly runs off into the river, adding to its volume and potentially causing it to overflow.

Given these complex flood scenarios, the need for advanced and accurate measurement tools is essential. ADCP (Acoustic Doppler Current Profiler) has emerged as a more sophisticated and convenient solution for closely monitoring the Aldan River’s flow dynamics.

3. How do ADCPs Using the Doppler Principle Work?

ADCPs operate based on the Doppler principle. They emit acoustic signals into the water of the Aldan River. When these acoustic waves encounter moving particles in the water, such as sediment, small aquatic organisms, or ice fragments being carried by the current, the frequency of the reflected waves changes compared to the original emitted waves. This frequency shift, known as the Doppler shift, is directly related to the velocity of the moving particles and, by extension, the velocity of the water flow.

By using multiple acoustic beams sent out at different angles and receiving the reflected signals, ADCPs can measure the water flow velocity at various depths and locations within the water column. Advanced signal-processing algorithms then convert these measurements into detailed velocity profiles, which are crucial for understanding the hydrodynamic characteristics of the Aldan River.

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

Velocity Measurement: During flood events or periods of high water flow, ADCP current profiler can precisely measure the velocity of the water at different points along the Aldan River. This information is vital for assessing the erosive power of the floodwaters. For example, high-velocity flows near riverbanks can signal areas prone to erosion, allowing for timely implementation of preventive measures like bank reinforcement or the installation of erosion-control structures.

Flow Measurement Application: By integrating the measured velocity data over the cross-sectional area of the river, ADCP current meter can calculate the flow rate. Knowing the flow rate is essential for flood management as it enables accurate prediction of the amount of water passing through a specific section of the river. This data can guide decisions regarding flood-control structures, such as the opening or closing of sluice gates in small dams along the river.

Sediment Transport Research: The Aldan River transports a certain amount of sediment, especially during floods. ADCP flow meter can be used to study the movement of sediment during these events. By analyzing the relationship between water flow velocity and sediment concentration and movement patterns, it’s possible to understand how floods impact the sedimentation and erosion processes in the river, which is beneficial for maintaining the health of the riverbed and the overall ecological balance.

5. How can the Data Measured by ADCP be Utilized for Flood Warning and Risk Management of Aldan River?

Flood Warning

Velocity and Flow Data Monitoring: Continuous monitoring of the water flow velocity and flow rate using ADCP profiler provides real-time data. When these values exceed predefined thresholds, it can trigger an early-warning system. For example, if the flow rate at a key monitoring point near a populated area reaches a level indicating a high risk of flooding, an alert can be sent to local authorities and residents immediately.

Water Level Prediction and Warning: The velocity data obtained from ADCP meter can be combined with other hydrological models to predict water levels. By understanding 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, giving people ample time to prepare for potential floods.

Risk Management

Water Conservancy Project Scheduling Decision Support: The data from ADCP current meter is invaluable for making decisions about the operation of water conservancy projects along the Aldan River, such as small reservoirs and diversion channels. For instance, if the measured flow indicates a large flood is approaching, reservoir managers can release water in a controlled manner in advance to make room for the incoming floodwaters, reducing the risk of overtopping and subsequent damage.

Flood Disaster Assessment and Emergency Response: After a flood event, ADCP data can be used to assess the impact of the flood. This includes evaluating the extent of erosion, sediment deposition in different areas, and changes in the river channel’s morphology. Such information is crucial for formulating effective emergency response and post-disaster recovery plans.

6. What’s Needed for High-Quality Measurement of Aldan River Currents?

For high-quality measurement of the currents in the Aldan River, the equipment must meet several criteria. Firstly, it requires high material reliability. Given the harsh Siberian environment, with extreme cold, ice impacts, and the presence of sediment and debris in the river, the casing of the ADCP current profiler needs to be durable.

Secondly, a smaller size and lighter weight are preferable. This facilitates easy installation and deployment in the often remote and hard-to-reach areas along the river. Low power consumption is also essential to ensure continuous operation, especially in locations with limited power supply. Cost-effectiveness is another crucial factor, as large-scale deployment might be necessary for comprehensive river monitoring.

Titanium alloy is an ideal material for the ADCP flow meter casing. It has remarkable strength, enabling it to withstand the mechanical forces exerted by flowing water, ice collisions, and debris impacts. Additionally, it exhibits excellent corrosion resistance, which is vital in the water-rich environment of the Aldan River, ensuring the long-term stability and accuracy of the equipment’s performance.

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

Based on Usage Purpose: For horizontal cross-section measurement of the river, horizontal ADCP (HADCP) is the optimal choice. It provides a detailed view of the flow velocity distribution across the width of the river, which is useful for understanding the overall flow pattern. For vertical cross-section measurement, vertical ADCP should be selected as it can accurately measure the velocity profile in the vertical direction.

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 appropriate for water depths up to around 70m, which can cover many sections of the Aldan River. A 300 kHz ADCP is more suitable for deeper water, up to about 110m, and can be used in areas where the river is deeper.

There are several well-known ADCP profiler brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective alternative, the China Sonar ​PandaADCP is highly recommended. It is made of all-titanium alloy material, offering excellent durability and 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.