How to measure the water current of the Kura River?

1. Where is the Kura River?

The Kura River is one of the largest and most powerful rivers in the South Caucasus region, its course passing through several countries. It originates in the highlands of northeastern Turkey-precisely within the Kars Plateau area of the Anatolian Plateau-and from there embarks on a long journey.

This river flows east to form a natural boundary between Turkey and Georgia, after which it totally falls within Georgia. In Georgia, it winds through some of the most beautiful valleys and pastures, with several towns and villages falling en route with which it shares almost a traditional acquaintance. People depend on irrigation from the Kura River, which again supports their agricultural activities, since Georgia is a very farm-based country. It is used both for domestic water and was considerable in the area as a form of transportation, boats crossing it.

Further on, the Kura River flows through Azerbaijan and is crucially important in many ways for industrial and urban development within the country. The cities are lined on the steppes, like Baku, with water for industries based on this river, fishing is based on it, and also it forms part of the local ecosystem.

From a purely geographical feature, the Kura River is a cultural and ecological cornerstone. Its surrounding areas host a diverse range of wildlife, including various fish species that thrive in its waters up to birds that flock to its banks and adjacent wetlands. The floodplains along the river are fertile grounds that contribute to the biodiversity of the region.

2. What is the Kura River Flow Rate Like?

The flow rate of the Kura River has great seasonal and regional variations. During spring, there is heavy influx into the river once the snow in most mountainous parts of its upper reaches, generally in Turkey, starts melting. This gives a good reason for its flow rate to rise very much. The melting snow from the peaks and highlands around it sends a large volume of water down its way, causing it to swell.

During this high flow period of usually March to May, the river can carry a few thousand cubic meters per second of water. This ensures the replenishment of groundwater supplies, filling up reservoirs along its course, and transportation of sediments, thus enriching the riverbanks and floodplains.

In summer, as the snowmelt effects reduce, the flow rate of the Kura starts to fall. Due to the absence of considerable precipitation and increased evaporation because of higher temperatures, the water amount in the river decreases. It still holds a base flow, which is very vital in sustaining the aquatic ecosystems and their corresponding functions like fishing and minor irrigation.

In the months of autumn and winter, it is always low, often falling to a few hundreds cubic meters per second. And in very severe winters, the upper reaches partly freeze.

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

Velocity Meter Method

The method involves the use of a velocity meter for measuring water current. It uses mechanical and electric velocity meters that are normally set at selected points along the river. These are fitted to measure the current water speed where the meter is faced. For a general assessment of the Kura River in terms of its general water current, several measurements must be set at various depths and sections. Considering the fact that a river can be long and complex, this is mostly labor-intensive and time-consuming.

ADCP Method

The Acoustic Doppler Current Profiler (ADCP) is more sophisticated and handy than the above-mentioned technique for current measurement. It basically works by emitting sound waves into the water and interpreting the Doppler shift of the reflected signals back to the instrument. Because the reflected waves are interactive with moving water particles, a change in the frequency of the reflected waves signifies the velocity of those particles. Remarkably, ADCP can measure the velocity of water at multiple depths simultaneously, which allows for detailed profiling of the water current throughout the river. Acoustic doppler flow meter can be installed on boats, allowing for measurements while the boat is crossing the river, or they can be deployed from bridges or on buoys for a continuous measurement.

Buoy Method

The buoy technique consists of positioning buoys with sensors in the river. These buoys float on the surface of the water and can measure the water movement around them. It gives only some indications about the surface current and cannot capture the variation of velocity at different depths in the Kura River accurately. However, it is comparatively easy and inexpensive to get a basic sense of water movement on the surface.

Among these ADCP current meter techniques, it is much more progressive and effective for the measurement of water current in the Kura River to get more valuable and detailed information about flow conditions.

4. How Do ADCPs Using the Doppler Principle Work?

ADCP current profiler work on the principle of frequency variation due to the relative motion between the source of the wave and the observer-a concept known as the Doppler principle. In this regard, an ADCP flow meter sends an acoustic signal (a sound wave) out into the water; the sound waves travel through the water column.

With these sound waves encountering the moving water particles, an interesting phenomenon takes place-if the water particles are moving towards the ADCP profiler, the frequency of the reflected sound wave returning to the ADCP meter is higher than the frequency of the wave originally emitted. If the particles are moving away from the ADCP, the frequency of the reflected wave will be lower.

The change in frequency, caused by the Doppler effect because of particle movement, is precisely measured by the acoustic doppler velocity meter to calculate the velocity of water particles at different depths. It then takes discrete measurements of this velocity at different depths and pieces together a full profile of the water current. In this way, a close understanding of the water flow can be made, not just at the surface, but throughout the vertical section of the river.

5. What Is Required to Obtain High-Quality Measurement of the Currents in the Kura River?

High-quality measurement of the currents in the Kura River will surely be based on several key factors concerning the used measuring equipment.

First of all, the equipment needs to be highly material reliable due to the following reasons: The variation of the water level in the Kura River, the variation of sediment loads carried within it, and the temperature difference between the warmest and coldest months of every year-this environment in the Kura River puts excessive demands on measurement devices that have to withstand continuous exposure to water, abrasive sediments in periods of high flow of any given year, and thermal extremes without mechanical failure or by corrosion attack.

Desired size, weight, and power should be small. Indeed, compact-size and lightweight devices would be much easier to handle and deploy both when being installed on board a boat for mobile measurement or fixed attached to a buoy. The power consumption should be low because in that way, the equipment will have the ability to operate for longer periods of time without changing the batteries or always having a source of power, which is quite crucially needed in areas across the river.

Cost is another major factor: the lower the cost of the measuring equipment, the wider the deployment that can be done, hence the coverage area for the length and different sections of the Kura River could be covered much better.

For the casing of the ADCP, titanium alloy is one of the best materials. Many are the advantages that come with the titanium alloy. It has very good corrosion resistance, something that is considered vital in dealings that involve contact with rivers such as Kura, where water may always have in solution all kinds of dissolved salts and other corrosive substances. The material is also very powerful and resistant. It resists all physical impacts from floating debris or ice in different seasons, according to the pressure changes occurring at various depths of submersion or in variations of the flow of the river. Second, titanium alloy has a relatively low density, and that keeps the overall weight of the equipment light, further facilitating its handling and deployment.

6. How to Choose the Right Equipment for Current Measurement?

Selection of appropriate equipment for current measurement in the Kura River will be based on two aspects.

Based on the Purpose of Use

Horizontal ADCP (HADCP): If the purpose is related to measuring the current of the river in relation to the horizontal cross-section, then this type is the most suitable form of instrument. HADCPs are designed to measure the flow of water in the horizontal plane with accuracy. That, however, is very useful in understanding the general movement of water across any given section of the Kura River, such as how water is distributed and flowing between different banks or across a given reach of the river. Vertical ADCP: In case the focus of attention is on the vertical cross-section measurement, one can go for a Vertical ADCP. These sorts of ADCPs can even measure the water velocity against depth with great accuracy. This gives a very high-resolution profile of the water's vertical flow within the river, crucial to understand such processes as sediment transport and nutrient distribution within the water column, or the behavior of aquatic organisms responsive to the vertical flow patterns.

Frequency Dependence

Frequency for the ADCP would depend on the depth of water in the Kura River. The 600 kHz frequency is quite suitable for water depths up to 70 meters. As a matter of fact, it provides good resolution and accuracy with respect to measuring water current in relatively shallower waters. It effectively detects and measures the velocity variations of the water particles at different depths within this range to provide reliable data for analysis. Where there are deeper waters of more than 70 meters going to about 110 meters, a better match would be the 300 kHz ADCP. Greater in-water penetration occurs at the low frequency of 300 kHz down to depth that provides accurate measurement of the water current.

Several of these well-known brands are available on the market including Teledyne RDI, Nortek, and Sontek. However, for those searching for an affordable option without any compromising on quality, the China Sonar PandaADCP serves as a good option. It uses all-titanium alloy material in its build, guaranteeing solidity and strength. With its excellent cost-to-performance ratio, it is an excellent alternative in obtaining the water current of the Kura River. For more information about the product, refer to: https://china-sonar.com/.

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