How to Measure Water Current of Kherlen River (Heilong Jiang)?

1. Where is Kherlen River (Heilong Jiang)?

The Kherlen River (Heilong Jiang) is a significant river that lies in Northeast Asia. It mainly runs through Mongolia and forms part of the greater Heilong Jiang system. The river originates from mountainous areas of Mongolia.

While meandering across the Mongolian landscape, the river flows through boundless steppes and semi-arid areas. These areas are a home for numerous wild horses, gazelles, and many species of birds. These animals find in the river a vital source of water, just as the flora that surrounds them does. Along its banks are nomadic herding communities, which rely on the Kherlen River (Heilong Jiang) for watering of their livestock and for their domestic water needs.

The river culturally breathes into the traditions of the Mongolian people, where it was included in the nomadic life and history of the Mongolians. Its waters are usually associated with various stories and songs passed between generations and symbolize bonds between people and land.

2. What does the discharge of the Kherlen River (Heilong Jiang) look like?

The Kherlen River (Heilong Jiang) is crucial in the local water circle and ecosystem. Its flow rate heavily depends on the seasons.

In spring, snowmelt in the mountains upstream raises the river's flow by a fair amount. The water level goes up, and the current gets rather strong. This is the critical period for the transport of sediments and nutrients that enrich the areas downstream and the floodplains sideways.

During summer, to a certain extent, the flow rate stabilizes. It nonetheless remains a regular water source for the local communities as well as the wildlife that need it. Its flow depends on a combination of factors that relate to rainfall in the catchment area and release of groundwater from the ground. In fall and winter, the flow rate is low. Its average flow rate is influenced by various factors such as how much snow falls in its upstream regions, the topography of its river basin, and how water collected is drained downstream by local communities.

3. How to measure water current of Kherlen River (Heilong Jiang)?

There are several methods that measure the water current of the Kherlen River (Heilong Jiang):

Velocity Meter Method

Conventional systems of current determination traditionally make use of mechanical or electronic velocity meters. A series of meters would be placed in the water at specific locations and measure the speed of water that moves around them. However, for an intensive study of the current, multiple placements at various places and different depths will be required, which could be quite time-consuming and not give a continuous profile across the water column.

Acoustic Doppler Current Profiler (ADCP) Method

The ADCP is a more modern and efficient method of measuring water current, utilizing sound waves to measure the velocity of water simultaneously at different depths. By emitting acoustic signals and analyzing the Doppler shift of the reflected signals, it can create a detailed profile of the current from the surface to the riverbed. This enables a more precise and comprehensive measurement of the water current across different sections of the river.

Buoy Method

In this method, buoys are installed in the river and their movements tracked with time. The displacement of the buoys due to the current water gives an indication of speed and direction of flow. Nevertheless, this method has its limitations, including not being able to provide velocity at different depths with considerable accuracy, besides being at the mercy of wind, waves, and other disturbing forces that can affect the buoy's motion.

Among these methods, the ADCP method is the more advanced and convenient option for measuring the water current of the Kherlen River (Heilong Jiang).

4. How do ADCPs using the Doppler principle work?

ADCPs work according to the principle of the Doppler effect. A specific acoustic signal is given off from the ADCP transducer into the water, and through its movement, the sound waves interact with the moving particles. Due to the flow of water, reflected sound waves back to the transducer have a different frequency level, which is called a Doppler shift.

This principle states that if the water is moving towards the transducer, the frequency of the reflected waves will be higher than the emitted one, whereas the frequency will be lower when the water is moving away from the transducer. These angular, small-scale changes in frequency-precisely measured-the ADCP calculates the velocity of water along and across the direction at various levels within the column. This enables it to create a detailed profile of the water current, providing valuable information about the speed and direction of the flow from the surface to the riverbed.

5. What's needed for high - quality measurement of Kherlen River (Heilong Jiang) currents?

The measuring equipment for high - quality measurement of the Kherlen River currents should possess some relevant characteristics. First, its materials of construction should be of dependable quality to ensure that the measurements taken would be correct and repeatable. Small size is appropriate to allow for easier deployments and recoveries in a river, especially in areas with difficult access. It has to be lightweight also so as to simplify the operations of installation and handling with minimal effort.

While in that it may work several hours without additional charge, low-power consumption can be achieved with sufficient care in hardware design. Costs also needed for the measuring campaign to permit wide spreading and larger - scale campaigns.

The other very essential feature is on the housing of the ADCP is it highly prefers with the alloy of titanium: " Titanium alloy has very great advantages. Because this piece of equipment is in constant contact with the water, which may carry an assortment of minerals, sediments, and pollutants, high corrosion resistance is absolutely necessary. Good strength to weight ratio: this ensures that the casing will be strong enough, yet as lightweight as possible. Be able to handle the mechanical stresses it experiences as the structure is deployed into and functioning in the moving water of the Kherlen River (Heilong Jiang).

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

The selection of the appropriate equipment to measure the current of Kherlen River (Heilong Jiang) depends basically on two major factors.

Depending on the purpose of use, for example, in the case of a horizontal cross-section, Horizontal ADCP (HADCP) is quite suitable. It is designed to effectively measure the flow velocities over a horizontal plane in the river, which is useful in understanding the current's lateral distribution. Vertical cross-section measurement would be better suited to the Vertical ADCP since this deals with profiling the current from surface to bottom along a vertical line in the water column.

Different frequencies of ADCPs would be suitable for different water depth conditions. For example, an ADCP with a frequency of 600 kHz is suitable to measure water depths within 70 m, while it will be ideal for the relatively shallower part of the Kherlen River (Heilong Jiang), providing current measurements quite accurately. An ADCP having a frequency of 300 kHz is more appropriate when the water is up to 110 m deep, which can be useful in areas of the river with greater depths.

There are well - known brands of ADCPs such as Teledyne RDI, Nortek, and Sontek. However, for those looking for 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.