How to Measure Water Current of Ider River?

1. Where is Ider River?

The Ider River is a beautiful river that meanders through the lands of Mongolia. It originates from mountainous parts of the country, where it starts as a gathering of small streams fed by glacial meltwaters and rainfall. Further downstream, it cuts across beautiful valleys with vibrant meadows and sparse forests.

It forms an integral part of the local ecosystem, housing all types of wildlife. From different species of fish swimming in its crystal-clear waters to birds sitting on its banks and finding their prey, Ider River shelters an entire energetic community of flora and fauna. Along the course of the river are also small settlements and herding communities dependent upon it. The local people use its water for domestic purposes like drinking and cooking, and it also serves as a water source for their livestock.

The Ider River culturally has a lot of significance in the traditions and stories of the local communities. It has been part of their lives for generations, with festivals and rituals sometimes centered around it. The riverbanks are places where children play, and adults gather to share tales of the past, making it a symbol of community and a connection to the land.

2. What is the flow rate of the Ider river?

Ider is the very important and major river that crosses regions. The Ider's rate changes very strongly through a year. At first, snow melting starts in spring months; therefore, the amount of water starts to strongly increase. This rapidly rises the level of the river, making the stream very forceful. This abrupt change brings into the river lot of sediments and nutrients valuable for its ecosystem, strengthening the bed and the space around.

The flow rate stabilizes to some extent during the summer, although it still depends on the rainfall in the catchment area. It continues to supply water for the local communities and the needs of the wildlife. During fall and winter, the flow rate is decreased. This includes snowfall amount in the upstream catchments, topography of the river basin that outlines the collection and drainage of the water, and the consumption pattern of the riparian communities. All these put together result in an average flow rate.

3. How to measure water current of Ider River?

There are various ways to measure the water current of Ider River:

Velocity Meter Method

The traditional method involves the use of mechanical or electronic velocity meters. These are placed at certain points in water to measure the speed at which water is passing by a given point. However, for a proper understanding of the current, placements have to be done at multiple locations and depths, which can be very time-consuming and may not necessarily provide a continuous profile of the current throughout the column of water.

Acoustic Doppler Current Profiler (ADCP) Method

The Acoustic Doppler Current Profiler (ADCP) method is more advanced and efficient to measure water current. It measures water velocity at different depths simultaneously. To achieve its detailed profile of current from the surface to the riverbed, it emits acoustic signals and analyzes the Doppler shift of the reflected signal. Therefore, the measurement of water current will be more accurate and comprehensive, as it is gathered across various sections.

Buoy Method

The method mainly comprises the use of buoys placed in a river and traced for some time. The shifts that these buoys undergo because of water flow give an estimate about the velocity and direction of the flow. However, it does not provide exact data concerning velocity at different depths; secondly, the movement of these floating buoys is affected by factors such as wind and wave actions.

Among these methods, the ADCP current meter method is more advanced and convenient for measuring the water current of the Ider River.

4. How do Doppler principle-based ADCPs work?

ADCPs work on the principle of the Doppler effect. An acoustic signal emitted from the ADCP flow meter transducer into the water-the sound waves interact with the moving particles of water. Due to the flow of water, the frequency of the reflected sound waves back to the transducer changes, a phenomenon known as 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 current profiler can calculate the velocity of the water in different directions and at different levels within the water column. It allows it to make an accurate profile of the current of water and thus very useful information about the rate and direction of flow from surface to riverbed.

5. What's needed for high-quality measurement of Ider river currents?

For high-quality measurement of the Ider River currents, the measuring equipment should possess certain characteristics. The materials used in its construction need to be reliable to ensure accurate and consistent measurements. A small size is beneficial as it allows for easier deployment and retrieval in the river, especially in areas with difficult access. The equipment should also be lightweight to simplify the installation process and reduce the effort required for handling.

The low power consumption is necessary for the equipment to work for hours, even days, without the requirement to change the batteries frequently or have an intricate setup for a power supply. Cost-effectiveness is also an important factor because through it, more widespread usage and larger-scale measurement campaigns would be possible.

Titanium alloy can be used for the casing of an ADCP profiler. Titanium alloy has a lot of advantages. It is highly resistant to corrosion, as the equipment will be in constant contact with water that may have different minerals, sediments, and pollutants. This has a good strength-to-weight ratio, which can provide a durable but lightweight casing. It can also withstand the mechanical stresses that happen during deployment and operation in the flowing water of the Ider River.

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

While selecting proper equipment to measure the current of the Ider River, two major factors shall be considered.

Depending on the purpose of use, for the measurement at horizontal cross-section, HADCP shall be used. It is designed to precisely measure flow velocities across a horizontal plane in the river, which gives good insight into the lateral distribution of the current. In the case of a vertical cross-section measurement, the Vertical ADCP is more appropriate because it profiles the current from the surface to the bottom along a vertical line in the water column.

Different frequencies of ADCPs are suitable for different water depths. For example, an ADCP flow meter with a frequency of 600 kHz is suitable for water depths within 70 m. It can provide accurate current measurements in relatively shallower parts of the Ider River. An ADCP with a frequency of 300 kHz is more appropriate for deeper waters up to 110 m, which can be useful in areas where the river has greater depth.

For this, there are some popular brands like Teledyne RDI, Nortek, and Sontek. But, considering quality with affordability, China Sonar PandaADCP will be highly recommended. It's made of all-titanium alloy material and enjoys an incredible price-performance ratio. More details can be found on its website: https://china-sonar.com/.

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