How to Measure Water Current of Angara River?

1. Where is Angara River?

The Angara River is one of the important rivers in Russia. It originates from Lake Baikal, which is known to be one of the deepest and most voluminous freshwater lakes in the world. Starting from the southernmost part of Lake Baikal near the town of Listvyanka, the Angara River then flows north through a complex and striking landscape.

This river flows through a territory with taiga forests, rolling hills, and large expanses of plains. Along its course, it passes through a number of cities and towns, among which Irkutsk is the most prominent, being a great urban center with rich historical and cultural traditions. The Angara River is an important contributor to all these communities. For them, it serves as a source of water supply, in industry, and it develops different branches of economy-fishing and power production.

The Angara River is culturally very significant to the people who live in this region. It has been a part of the folklore, passed down through stories and legends for generations. The riverbanks are often the sites of festivals and recreational activities, and its waters have seen the growth and development of the surrounding areas over centuries.

2. What is the Angara River like concerning flow rate?

The flow rate of the Angara River is determined by various conditions and also has some features peculiar to it. Lake Baikal is one of the important feeding sources of the Angara, and the volume of water discharged from it strongly influences the flow rate of the river.

Seasonally, during the spring, snowmelt in the surrounding catchment areas, along with the release of water from Lake Baikal, results in an increase in the river's flow. The water level rises, and the current becomes stronger. This period is crucial for the transportation of sediments and nutrients downstream, enriching the riverbed and the adjacent floodplains.

In summer, the flow is also relatively stable but continues with an adequate supply of water toward all the needs of the region. The sustenance of the river in its flow is maintained by both the continued inflow from Lake Baikal and contributions from generally small tributaries. This decreases further during the fall and winter seasons.

However, because of the enormous volume of water stored in Lake Baikal and the river's own water-holding capacity, it never dries up or actually stops flowing. Other factors affecting the average flow rate include precipitation levels in the upstream catchment areas, topography of the river basin determining catchment of water and runoff, and hydroelectric dams along the river.

3. How to measure water current of Angara River?

There are a few ways by which one can measure the water current of the Angara River:

Velocity Meter Method

This traditional approach utilizes mechanical or electronic velocity meters. Meters are installed at discrete points in the water to quantify the speed of the water passing by the meter. However, to get a decent measurement of the current, many placements at different locations and depths are needed; this can be quite laborious and may not result in a continuous profile over the depth range.

Acoustic Doppler Current Profiler (ADCP) Method

The Acoustic Doppler Current Profiler (ADCP) is an advanced method for the measurement of water current, measuring simultaneously at every depth the speed of water. By sending acoustic signals and observing the Doppler shift from the reflected signal, it could create a profile in detail of the current right from the surface to the riverbed. Thus, accurate and comprehensive measurements of the water current at different sections in the river can be recorded.

Buoy Method

In this method, buoys are placed in the river and their movements over time are monitored. The movement of the buoys by the action of the water current indicates the speed and direction of flow. Nevertheless, this method has many limitations: it cannot show the exact velocity at different levels and is usually subject to changes in external factors such as wind and waves, which may influence the movement of the buoys themselves.

Among them, the ADCP current meter method is more advanced and convenient for measuring the Angara River's water current.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of the Doppler effect. When an acoustic signal is transmitted from the ADCP current profiler transducer into the water, the sound waves encounter and interact with the moving particles of water. Due to the flow of water, the frequency of the reflected sound waves back to the transducer shifts; this is what is called the Doppler shift.

If the water is moving towards the transducer, the frequency of the reflected waves will be higher than the emitted frequency. If the water is moving away from the transducer, the frequency will be lower. By precisely measuring this frequency shift at multiple angles and depths, the ADCP flow meter is able to calculate the velocity of the water in different directions and at different levels within the water column. This enables it to make a detailed profile of the water current, carrying useful information on the speed and direction of flow from the surface down to the riverbed.

5. What is required for high-quality measurement of Angara river currents?

For high-quality measurement of currents in the Angara River, the measuring equipment should have the following features.

The materials used to build it should be reliable to give accurate and constant measures. Any defect or instability in the materials could lead to errors in the data collected on the current of the river.

A small size is advantageous to the equipment because it enhances the deployment and retrieval in the river, particularly at places that may be inaccessible. Besides being lightweight aids in ease of installation and reduces the labor of handling the equipment.

The power consumption should be low. This will ensure that the equipment can operate for extended periods without the need for frequent battery replacements or a complex power supply setup. This is particularly important given the potentially remote locations along the Angara River where accessing the equipment for maintenance might be inconvenient.

Cost-effectiveness is another important consideration. Equipment that can provide good performance at reasonable cost can be used more widely and in larger measurement campaigns, contributing to a better understanding of the current of the river over sections and time.

For the casing of the ADCP meter, titanium alloy is an excellent choice. Titanium alloy has several advantages. It is highly resistant to corrosion, which is crucial as the equipment is constantly in contact with water that may contain various minerals, sediments, and pollutants. This resistance ensures the longevity and durability of the device, protecting its internal components from damage caused by the aquatic environment.

Moreover, titanium alloy has a good strength-to-weight ratio, allowing for a durable yet lightweight casing. This allows the casing to be resistant to the mechanical stresses during its deployment and operation in the flowing water of the Angara River without adding excess weight to the equipment.

6. Selection of Equipment for Current Measurement?

While choosing appropriate equipment for measuring the current of the Angara River, two things shall be considered.

Some of the ADCPs work for different measurement requirements, depending on the purpose of use. For horizontal cross-section measurement, HADCP is the one for the job. The HADCP is designed to measure the flow velocities across a horizontal plane in the river with high accuracy; it serves to illustrate the lateral distribution of the current.

Where measurement across the vertical cross-section is involved, the Vertical ADCP would be better. It essentially profiles the current from the surface to the bottom along a vertical line in the water column to deliver highly detailed information about the changes in flow velocity with depth and its influence on the riverbed and aquatic life.

Second, different frequencies of ADCPs suit different water depths. For example, an ADCP profiler with a frequency of 600 kHz is suitable for water depths within 70 m. It can give accurate current measurements in relatively shallower parts of the Angara River. With a frequency of 300 kHz, an ADCP is more appropriate for deeper waters, up to 110 m, which could be useful in areas where the river has greater depth.

There are well-known brands of ADCPs such as Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective option with good quality, the China Sonar PandaADCP is highly recommended. It is made of all-titanium alloy material and offers an incredible price-performance ratio. You can find out more about it on its website: https://china-sonar.com/.

Here is a table with some well known ADCP instrument brands and models.