ADCP in the Angara River Flood Management

1. Where is the Angara River?

The Angara River is located in Russia. This is one of the significant tributaries of the Yenisei River. The origin of this river is Lake Baikal, known as the world's deepest and one among the largest freshwater lakes.

From Lake Baikal, it enters into a vast taiga region, plain, and mountainous outcrops along its upper course. Some cities and towns lie along the way, where water supply forms an important part of the local economy, such as industrial requirements for water supply, generation of hydroelectricity, and domestic water.

The Angara River passes through areas which are characterized by the seasonal continental climate. The whole year is dominated by long, cold winters with heavy snowfalls in the upper parts. Melting of snow and rainfall mark spring and summer. Melting of snow from the surrounding regions, particularly from the mountains and the large catchment area, supports the volume considerably. Since snowmelt combined with rainfall can result in the fluctuation of water levels, heavy precipitation or rapid snowmelt may provide conditions for flooding.

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

Melted Snow and Heavy Rainfall: Spring is the time when snow melts in the mountains, and heavy precipitation at this time in the wet season is considered the major reason for producing floods. The large quantity of water melting in a huge catchment area with additional rainwater can increase the river volume in a very short time. The mountainous upper stretches hasten runoff and send an enormous amount of water downstream.

Topography: The occurrence of floodplains and low-lying areas within its course allows for water spreading and, thus, its accumulation. Such plains gently slope, slowing down the flow of water; thus, it increases the chances of flooding. Where there is a confluence of tributaries with the main stream, these can introduce additional water at times of high flow and, therefore, can aggravate the flood situation.

Human - Induced Changes: Deforestation in the catchment area leads to a decrease in the capacity of the forest to intercept and retain rainwater. In addition, it leads to soil erosion and the eroded topsoil eventually deposits in the river, thereby reducing its carrying capacity. Building dams and other water-related structures can also at times interfere with the natural pattern of the flow and drainage of water.

An ADCP current meter can also be a useful tool for understanding and managing Angara River flow during flooding conditions.

3. How do Doppler principle utilizing ADCPs work?

ADCPs apply the principle of the Doppler effect. The instrument sends an acoustic signal into the water. Because of its flow, the signal interacts with the moving particles in the water. After interaction, the reflected signal bounces back to the Acoustic Doppler Current Profiler (ADCP) with a different frequency because of the Doppler effect.

This ADCP doppler calculates the frequency difference between the transmitted signal and the received one. Using this frequency shift, it can then work out the water velocity at different depths. Most ADCPs come with multiple transducers that send acoustic signals as well as receive these in various directions. Working from them, they would then calculate a profile of water velocity across the section.

For instance, if the water is running in the ADCP direction, the reflected signal will have a higher frequency than that of the emitted one. Conversely, if the water is running away from the ADCP profiler, it would reflect a lower frequency. The change of frequency values is measured with high precision, and appropriate calculations through the mathematical algorithms return the right amount of the velocity of the water at different points within its measurement range.

4. Kinds and Areas of Utilization of ADCP in Floods of the Angara River

Velocity Measurement

The ADCP flow meter contributes to finding the actual velocity of water flow during flood events in the Angara River. Monitoring at all different depths and various locations continuously, it would give real-time data on the speed at which the water would be traveling. This is a key piece of information when trying to understand the dynamics involved with the flood-for example, predicting the direction and intensity of the movement of the floodwaters.

Flow Measurement Application

Another potential application of ADCP current meter is the measurement of the flow rate of the Angara River. By combining measured velocities at various points across a section of the river with known cross-sectional area of the river, it can compute the total volume of water that flows through the section within unit time-the flow rate. This information is valuable in determining the general volume of water during flooding and aids in making choices on flood control and water resource management.

Applicability in Sediment Transport Study

Apart from measuring flow and velocity, ADCP can be applied in sediment transport study along the Angara River during flooding. When flowing water moves, it carries with it some portions of particles in suspension. The ADCP can measure the changes in the backscattered acoustic signal produced by the presence of sediments. From these changes, researchers can estimate the quantity and movement of sediments important in understanding the long-term evolution of the riverbed and flood impacts on the river sedimentary environment.

5. How the data, acquired with ADCP, can be used for providing warnings and risk management in general, related to Angara River flooding?

Warning

Data from ADCP doppler on real-time velocity and flow data are continuously monitored for this purpose. If the measured water velocity is over a certain threshold, or if the flow rate suddenly surges, that may indicate the approach of a flood peak or possible flood. If there is an early warning, relevant authorities can ensure more preventive measures to protect the people in low-lying areas or strengthen their flood defenses.

Measured flow data correlated with historic water level data using appropriate hydrological models can help in the prediction of future water levels using ADCP flow meter data. If the predicted water level is found to rise above the flood warning level, timely warnings can be issued to the public for their preparation against the flood.

Risk Management

Support of Scheduling Decision-Making for Water Conservancy Projects: The accurate flow and velocity data obtained from ADCP meter can be used to support the scheduling decision-making for operating the water conservancy projects like dams and sluices. For example, according to the measure of water flow, the amount released from the dam should be duly regulated with a view to maintaining the water level of Angara River to minimize flood disasters.

Flood Disaster Assessment and Emergency Response: All the data which ADCP profiler is able to collect following a flood event help in determining the severity of the flood by knowing the extent of the inundation, the velocity of the floodwaters, and the amount of sediment deposition. This will become very important for the formulation of emergency response plans and for the conduct of post-flood reconstruction and rehabilitation works.

6. What are the requirements for the high-quality measurement of Angara River currents?

High-quality measurement of Angara River currents requires several conditions. First of all, equipment should be made of reliable material. The casing of ADCP meter is of special concern. It is necessary to make the casing of the titanium alloy. The titanium alloy is very strong and hence can bear the pressure and jolts of the running water in the river. It is also resistant to corrosion, which is necessary due to the aquatic environment of the Angara River, which may contain several corrosive elements.

Besides the material reliability, the size and weight of the equipment should be minimal and light as possible. This allows for an easier installation and operation of the ADCP flow meter in an arbitrary part of a river, even in areas where accessibility is poor. Low power consumption is also of prime importance to enable longer continuous operation, without frequent replacement of batteries or the need for a connection to a power source. The price of the deployed instrument should be reasonably low to enable large-scale measurement. More ADCPs in the Angara River will mean lesser cost, and with more ADCPs, there will be more extensive and precise information for flood management.

7. Which is the correct equipment for measuring current?

Selection of Equipment for Current Measurement in Angara River Various aspects have to be considered in selecting the right equipment for current measurement in the Angara River. For example, based on the nature of the measurement required, if intended to be a horizontal cross-section measurement, then a Horizontal ADCP doppler, HADCP, should be used. If the measurement required would be vertical cross-section, then a Vertical ADCP current profiler will appropriately be used.

The reason behind it is different frequencies are suitable for different water depths. Such as a 600 kHz ADCP is suitable for a water depth within 70 m. So, in case the water depth in Angara River is within this range and the measurement requirement matches, a 600 kHz ADCP can be considered. However, for deeper waters such as over 70 m to 110 m, the 300 kHz ADCP will be more fitted because it gives better measurements in that depth.

Several well-known ADCP current meter brands are available in the market. Some of them are Teledyne RDI, Nortek, and Sontek. However, for users searching for economical options, China Sonar PandaADCP is a very good 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.