How to Measure Water Current of the Ishim?

1. Where is the Ishim?

The Ishim River is one of the major rivers in Kazakhstan. It is situated in the central part of the country, and its flow crosses from a landscape that blends steppe and semi-desert regions.

It originates from the south of the Ishim Plain, and while meandering across the plains, it serves as a source of water supply to the arid and semi-arid regions it passes through. The steppe around this river is a big grassland with an immense population of saiga antelopes, steppe eagles, and plenty of small mammals and birds.

Along its banks are small settlements and pieces of farmland. For the local inhabitants, the Ishim River is a source of irrigation, thereby serving as the basis of development for crops such as wheat and barley. The river constitutes both the natural boundary and transport route to the local community, though not as extensive as some of the larger rivers in this region.

2. What does the Flow Rate of the Ishim River look lik​e?

The Ishim River is subject to seasonal and climatic factors, which form its flow rate. In spring, due to the snowmelt in the surroundings, the river shows some increase of flow. During this period, the water level rises and the current is considerable. This higher flow period aids agriculture along its banks, as plenty of water is available for irrigation.

As summer months approach, the flow rate somewhat stabilizes, with slight variations depending on precipitation. During the dry season, which is more typical for such semi-desert areas, this rate drops. This can result in a shallow river since the flow in some places may be relatively slow. Even further, the average flow rate itself changes along the length of the river. While this is relatively rapid in the upper reaches near its source, it is decidedly retarded when the bed being flatter and spreads out.

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

There are several methods by which water current of the Ishim River can be measured.

Traditional Methods

Float Method: A very simple way to estimate water current is to use a float. The buoyant object is dropped into the river. It could be a piece of wood or even a plastic container. Surface current speed can be approximated with the distance and time it takes for the float to travel over the known distances. However, there is one major drawback with this technique. Such a measurement could easily be subject to wind and surface disturbances, as it can only provide information about the surface current - not at different depths. 

Current Meters: Either mechanical or electrical these are devices set in the water at a known depth to measure the relative speed of the water passing by them. While the readings may prove to be more accurate at that one point in the water column than the float method, it does have the limitation of just being at that depth, not recording the entire current profile throughout the water column.

Advanced Method - Acoustic Doppler Current Profiler (ADCP) The water current of the Ishim River can be gauged in a more advanced and efficient way by using ADCPs.

3.1 How do ADCPs using the principle of Doppler work?

The basic principle in the working of ADCP current meter is the Doppler effect. The device emits acoustic pulses into the water. The pulses interact with the suspended particles and other materials of the water, such as sediment and small organisms. In this flow motion of water, the frequency of the reflected acoustic signals changes. 

This frequency shift is measured by the ADCP current profiler and using the Doppler formula, it is transformed into the velocity of the water at a range of depths. By transmitting pulses in several different directions and each at a number of frequencies, an ADCP doppler can generate a highly detailed profile of the water current throughout the water column. A finer resolution of the current structure of the river is achieved than if the current is measured by traditional methods at either the surface or a single point in the water column.

3.2 What is necessary for high-quality measurement of Ishim river currents? 

Apparatus prescribed for reliable results of the Ishim river currents measurement must be applied in real conditions. Measuring devices should be able to sustain these circumstances taking into account such arid and semi-arid climate conditions as dust storms and sharp temperature fluctuations. 

The equipment has to be compact and lightweight. This is essential for ease of deployment, especially in remote areas along the river or from boats. A low power consumption is also desirable in order to operate the equipment over an extended time without frequent battery changes or the need for an outside power source. Another factor that is very important is cost-effectiveness because large-scale measurements might become necessary in understanding river dynamics. 

Using a titanium alloy casing on ADCP flow meter has advantages. It provides high resistance to corrosion, which is very essential in a water-rich environment like the Ishim River. It is very strong and durable, hence can withstand physical forces involved due to the river current and its impacts. Its light weight makes it more convenient for installation and transportation.

3.3 How to Choose the right equipment for current measurement? 

While selecting equipment for measurement of Ishim River Current, the particular requirements of measurement should be kept in mind. 

For Horizontal Measurements: Horizontal ADCP was one of the possible choices in the case of horizontal measurements across a section of the river. This instrument projects a wide fan of the acoustic signal in the horizontal plane and allows visualization of the current flow over a section of the river. 

For Vertical Profile Measurements: The same for the vertical profile measurements of current, better measured by a vertical ADCP. The information on the water velocity at various depths, important in studying stratification and mixing of the water column, can be obtained in greater detail. 

Frequency Selection: In the case of relatively shallow reaches of the Ishim River-one would estimate up to approximately 70 meters-, a 600 kHz. ADCP should suffice, while in deeper reaches-estimated up to about 110 meters-the better choice 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 Ishim 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.