How to Measure Water Current of the Aldan River?

1. Where is the Aldan?

The Aldan River is a major water body of the Russian Far East. It is located in the Sakha Republic (Yakutia), which is the most extensive and cold region. The river originates in the Stanovoy Highlands and passes through a land composed mainly of taiga forests with permafrost.

The mountainous terrain falls into the higher courses of the Aldan River. The clear, cold waters are supplied partly by snowmelt and partly by springs in the highlands. While meandering down through the taiga, it forms a very important source of water for the entire forest ecosystem. Its banks support elk, lynx, and numerous bird species, including fish such as grayling and lenok, which form a very important fishery.

It has served as one route of communication and transportation for many years, besides playing a significant role in the history and culture of native peoples in the region. Small settlements line its banks, some totally dependent on the river for water supplies, fishing, and small-scale hydroelectric power generation.

2. How does the Flow Rate of the Aldan River portray itself?

The flow rate in the Aldan River is highly seasonal. During spring, with the beginning of the melting of snow and ice in the Stanovoy Highlands and areas around it, there is a sudden rise in the river's flow. With the rise in water volume, the current becomes very strong. This period of high flow bears crucial relations with the general dynamics of the river and with downstream transport of sediments and nutrients.

During the very long and cold winter, the flow rate is radically reduced. The river freezes over; in some areas, this is often used as an ice road. The average flow is also modified through a river- from the source to the mouth. In the upper reaches, closer to its source, the much steeper gradient might force the water to flow a little faster. While advancing through the flatter regions, the flow is slower and the river wider.

3. How to Measure Water Current of the Aldan River?

There is more than one way of measuring the water current of the Aldan River.

Traditional Methods

Float Method: A very basic and traditional way of estimating the water current is by using a float. For instance, a buoyant object, such as a block of wood or a plastic container, is dropped into the river. By estimating the time it travels over a known distance, one could get an approximate value of the surface current speed. However, this technique is greatly affected by the wind and wave disturbances on the surface. Furthermore, it cannot provide any data concerning the lower layers but information about the surface current alone. 

Current Meters: These can be mechanical or electrical and can also work out the speed of the water at any single point. These meters are positioned in the water at a certain depth and give the speed of the water that is passing through it. These meters give an accurate measurement on a single point rather than floats, but they do not provide the entire current profile across the column of water.

Advanced Approach: Acoustic Doppler Current Profiler (ADCP) 

ADCPs are the higher degree and efficient method of measurement concerning the water current of the Aldan River.

3.1 How do the ADCPs using the principle of Doppler work?

ADCP current meter work on the principle of the 'Doppler effect'. The instrument emits an acoustic pulse through the water. The pulses interact with in-water suspended particles and other materials, like sediment and small life forms. If the water is moving, the frequency of the reflected acoustic signals will change. 

The ADCP current profiler measures this frequency shift by using the Doppler formula and computes the water velocity at different depths. An ADCP doppler sends out pulses in several directions with varied frequencies, based on which it develops a detailed profile of the water current throughout the depth of the water column. This serves as an overview of the structure of the current of the river in more detail compared to traditional methods.

3.2 What needs to be done to achieve the high - quality measurement of the currents of the Aldan River? 

Reliable equipment for high - quality measurements of the Aldan river currents is necessary. Considering the very low temperatures and possible ice damage, the measuring devices have to be capable of operating under such conditions. 

The equipment to be used must be compact and lightweight, as this will be necessary in terms of deployment: some sites along the river might not be easy to access. The power consumed should also be low to enable substantial length in operation without changes in batteries or external power supplies. Cost-effectiveness is very key to this, in that it may require large-scale measurements. 

Application of titanium alloy in the casing of ADCP flow meter is valuable. Such alloys have great resistance to corrosion, which is important in water-rich environments like the Aldan River. It is also strong and able to resist physical forces that may result from the river current and any possible impacts; it is light, thereby making installation and transportation easier.

3.3 How to Choose the right equipment for current measurement?

Selection of equipment for the measurement of the Aldan River current should be based on the peculiarities of measurement at hand. 

For Horizontal Measurements: Horizontal measurement across the section of the river is a good choice if one wants to use an HADCP. Its wide viewing of current flow in the horizontal plane adds to our understanding of general patterns of flow that the river follows. 

For Vertical Profile Measurements: Vertical profile measurements of current can be better carried out by a vertical ADCP. It should provide detailed information on the velocity of the water with depth, which in turn is important for studying stratification and mixing of the water column. 

Frequency Choice: For frequency choice, a 600 kHz ADCP could work for the Aldan River at relatively shallow stretches-up to about 70 meters-or a better choice for deeper reaches, up to about 110 meters, is a 300 kHz ADCP.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option with good quality, the ChinaSonar PandaADCP is a great choice. It is made of all - titanium alloy, providing durability and resistance to the Aldan River's environment. It also offers an excellent price - performance ratio. You can visit https://china-sonar.com/ for more information.

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