ADCP's Application in Flood Management of Khatanga River

1. Where is Khatanga River?

Khatanga River is situated in the far northern part of Siberia, Russia. It is a major river that empties into the Khatanga Gulf of the Arctic Ocean.

Geographically, it passes through a region dominated by tundra and permafrost. Its course is a very significant part of the Arctic ecosystem: it provides a home for various cold-adapted species such as Arctic char, polar bears that may use its riverbanks and ice floes near the river, and a number of migratory birds during the short Arctic summer.

The Khatanga River Basin has a polar climate in terms of climate and rainfall. The area receives heavy snowfall during the long winter months. The snowmelt in spring, along with some limited summer rainfall, is the main contributor to the river's water volume. The summer is brief and relatively cool, and precipitation during this period is not as abundant as in more temperate regions.

2. Why Are There Floods in the Khatanga River?

Snowmelt and Heavy Rainfall: The leading cause of floods in the Khatanga River is snowmelt in spring with subsequent heavy rainfall during the short summer. With the vast area of the catchment, enormous water amounts may appear in the river in relatively short terms. This occurs when snow melts rapidly due to a sudden warm spell in conjunction with heavy rainfall, wherein the capacity of the river is surpassed.

Tributary Inflows: The Khatanga River has numerous tributaries. When these tributaries are experiencing high water levels due to their own snowmelt or rainfall, they can contribute a lot to the main river channel. Where there is a confluence of many such tributaries, this results in an instantaneous increase in the Khatanga River's water level and can be very flood-prone.

Topography and Drainage: The river flows through stretches with essentially flat floodplains, with some natural constrictions. On the flat floodplains, water slows down its flow and spreads over adjacent areas to flood them. The constrictions can impede the normal flow of water, causing it to back up and increase the water level upstream. Additionally, the permafrost in the area can affect the drainage patterns. When the permafrost thaws, it can change the soil's permeability and lead to waterlogging and flooding.

Climate Change-Induced Changes: In recent years, climate change has had an impact on the Arctic regions. Warmer temperatures can lead to more rapid snowmelt and changes in precipitation patterns. These alterations can increase the frequency and severity of floods in the Khatanga River. In this context, the Acoustic Doppler Current Profiler (ADCP) provides a more advanced and efficient measurement solution for flood-related data compared to traditional methods.

3. How Do ADCPs Using the Doppler Principle Work?

The operation of an ADCP current meter is based on the principle of the Doppler effect. ADCPs transmit acoustic signals into the water. When these acoustic waves interact with moving particles in the water, such as sediment, debris, or even water parcels with different velocities, the frequency of the reflected signals changes from the frequency of the emitted signals 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 Khatanga River?

Velocity Measurement: ADCP can measure the velocity of the water flow in the Khatanga River at different locations and depths with high accuracy. This information is highly 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 to the riverbanks, bridges if any, and the local settlements. It also allows monitoring how the flow velocity changes over time as the flood progresses.

Flow Rate Measurement Application: Combining the measured velocity data with the cross-sectional area of the river, ADCP can determine the flow rate. This becomes crucial in predicting the volume of water that will pass through different sections of the river during a flood. This helps in anticipating the peak flood and its consequences downstream, which is useful for planning flood management strategies.

Sediment Transport Research: Flooding in the Khatanga River can transport a huge amount of sediment. ADCP current profiler is able to analyze the sediment movements by detecting echoes of acoustic signals affected by sediment particles. This gives a lot of valuable information about how floods affect the evolution of the riverbed, sediment deposition, and erosion processes, which is very important for maintaining stability in the channel and the ecosystem.

5. How Can the Data Measured by ADCP Be Utilized in Flood Warning and Risk Management of Khatanga River?

Flood Warning

Velocity and Flow Rate Data Monitoring: ADCPS will continuously monitor the information about velocity and flow rate. This will result in an early warning about abnormal increases in these parameters, which can be considered critical as the flow rate approaches or has already exceeded certain critical values that may indicate a flood peak. This enables the issuance of timely flood warnings to the local communities and concerned authorities.

Water Level Prediction and Warning: The model can be developed by correlating the measured flow rate and velocity data with historical water level records to predict future changes in water level. This helps in providing advance warnings about the areas that may get inundated and the height of floodwaters.

Risk Management

Water Conservancy Project Scheduling Decision Support: Data from ADCP meter may help support decisions related to operating water conservancy projects along the Khatanga River, including small dams or reservoirs. For example, when it comes to decision-making, ADCP may be of assistance in making a correct choice about how much and when to discharge water from the reservoirs for the control of floods further downstream.

Flood Disasters Assessment and Emergency Response: In cases of just occurred floods, ADCP-measured data can be utilized directly to assess the extent of the flood, like extents of inundated area, flow characteristics during the flood, among others. All of this information guides the actual emergency response, hence determines the relief resource allocations, as well as the post-flood recovery work planning.

6. What is necessary for high-quality measurement of Khatanga River currents?

For high-quality measurement of Khatanga River currents, this equipment should be made from really reliable materials. The casing must be resistant to impacts in the river, including the ones from floating debris that might be more serious during floods; it should be resistant to the corrosion of water with its specific chemical composition, caused by the Arctic environment and huge differences in temperature from winter to summer.

The size of the equipment must be of a size that is manageable to install and deploy at multiple locations in the river, given the inaccessibility at some locations in the interior of the region. A lighter design also makes the equipment far easier to transport and install at the site of operation. It has to be of low power consumption to allow for continuous operation over long periods without changing batteries frequently or the use of high-energy power sources. Cost-effectiveness is another factor so that large-scale deployment can be allowed for wide area coverage of monitoring.

The casing of ADCP profiler is preferably made of titanium alloy. Titanium alloy has several outstanding advantages: it has excellent corrosion resistance, which is crucial for withstanding the long-term exposure to the river water; it has a high strength-to-weight ratio, providing sufficient strength while keeping the equipment's weight at a reasonable level. This material's durability ensures stable performance under the diverse environmental conditions of the Khatanga River Basin.

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

During the selection of appropriate equipment to measure current in the Khatanga River, the following factors should be considered. Depending on the purpose of usage, if the horizontal cross-section measurement is the point of concern, then the Horizontal ADCP-HADCP will be quite suitable as it can provide very accurate flow velocity and other parameter measurements in the horizontal direction across the river section. It will be more appropriate to apply the Vertical ADCP in vertical cross-section measurement, as it can obtain detailed velocity profiles along the vertical axis of the river.

Different frequencies should be chosen based on the actual water depth. Within 70 meters, the frequency of an ADCP is usually 600 KHz, which can offer relatively accurate measurement results in such a depth range. For deeper water areas of up to 110 meters, an ADCP with a frequency of 300 kHz is more suitable because it can penetrate effectively to greater depths and obtain reliable data.

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.