How to Measure Water Current of Tarim River?

1. Where is Tarim River?

The Tarim River represents one of the most important and particular watercourses of the northwest China arid area. This is the longest inland river in China, extending about 2,179 kilometers. Its source is fed by the confluence of several tributaries, originally coming from the mountains surrounding the Tarim Basin: Kunlun Mountains and Tianshan Mountains.

The course of the Tarim River twists through the big and arid Tarim Basin. It runs its course along the Xinjiang Uygur Autonomous Region in western China and holds great significance in this land of drought. The riverbanks are lined with oases that resemble emeralds in the desert. These oases fuel a large group of agricultural activities, from crops such as cotton, wheat to fruits. While doing so, the local communities, including different ethnic groups like Uyghur and Han, have depended for years on this river as a source of water and livelihood.

Geographically, the Tarim River is highly critical and important in the ecological environment within the region. The river and oases that it possesses become a habitat for a large number of rare and endangered species. Amazingly, the saux forest of Populus euphratica, which appears along the riverbanks, has adapted to such unfavorable conditions. These hardy trees can survive only from water drawn from the Tarim River. More than just a water course, the Tarim River is life and hope in this desert of desolation.

2. What does the Flow Rate of the Tarim River look like?

The Tarim River is a significant inland watercourse in northwest China, a part of arid regions. Considering it is an inland river, there are several reasons that may affect its flow rate and volume of water throughout the year. During the spring and summer seasons, most of the water contribution to the river comes from the snowmelts and glacier melts of the mountain ranges around it.

The average annual flow rate of the Tarim River is quite variable between years. In wet years, it has a relatively high flow rate of up to hundreds cubic meters per second, whereas in dry years, the flow may be drastically reduced, sometimes even as low as intermittent in some parts. The flow has also been regulated by the construction of water-conservancy projects such as reservoirs and canals serving agricultural irrigation and water-supply purposes. Such projects can help regulate the distribution of water within the river and its tributaries to make as effective use as possible of the available water resources.

The flow of the Tarim River is crucial to maintaining balance in the ecosystem of the Tarim Basin. The water allows for vegetation to develop in oases and on the banks to take place, preventing desertification by providing a suitable habitat for wildlife.

3. Measurement of Tarim River Water Current?

There are traditional and modern ways of measuring the water current of the Tarim River. The simple traditional method includes float-based techniques. Floats are released into the river, while their motion over some given distance and time is observed to estimate the surface current speed. Another way is by installing current meters at various points in the water and measuring the current velocity directly.

However, the most modern and handy ones up to date are the acoustic Doppler Current Profiler-ADCPs. It is the ADCP current meter that will give a more correct and instructive picture of water current in the Tarim River.

3.1 How Do ADCP Using the Doppler Principle Work?

Acoustic Doppler Current Profiler(ADCP) is based on the principle of the Doppler effect. They send acoustic pulses into the water. Due to the moving water particles, the frequency of the returning pulses will change. By this change in frequency, the ADCP calculates the water speed at each depth.

It has multiple transducers that are capable of transmitting acoustic signals in several directions, meaning it can measure the horizontal as well as the vertical components of water flow. This will, therefore, be able to view a three-dimensional representation of the Tarim River water current for possible research into complicated flow features caused by topographical characteristics among others.

3.2 What is Required for High-Quality Measurement of Tarim River Currents?

In the high-quality measurement of the Tarim River currents, ADCP current profiler depend on the characteristics of this equipment. In this regard, the casing of an ADCP doppler should be made of a reliable material, and one of the best options can be a titanium alloy.

There are many advantages using a titanium alloy. It is lightweight, which will be advantageous during transportation and deployment in the remote areas along the Tarim River. This alloy also possesses excellent corrosion resistance. With the chemical composition of the Tarim River water in combination with the harsh desert environment, the corrosion-resistant property of the titanium alloy is sure to provide the ADCP flow meter with long-term precision and stability.

Further, since there is a need for extensive measurements along the Tarim River, it should be of low power consumption and be low in cost. Low operation costs will allow for more general usage without making high demands on energy or finances. A low-power-consuming ADCP meter will also have the capability of operating for longer periods, which can help in continuous monitoring of the current of the river.

3.3 How to Choose the Right Equipment for Current Measurement?

Another critical factor in choosing the right type of ADCP profiler to measure Tarim River current is intended use. If the purpose is horizontal flow across a section of the river, then an HADCP will suffice. As their name suggests, the HADCPs are devised to measure the horizontal velocity components of the water current with accuracy.

In the case of vertical flow profile measurements, a Vertical Acoustic Doppler Current Profiler would be more appropriate. VADCPs are set up in such a way that they are able to measure the velocity of the water at variant depths along a vertical line in the river.

This would mean that for the relatively shallow sections of the Tarim River, 600 kHz applies, while the water depth is up to approximately 70 m. In the deep areas of the river, a 300 kHz ADCP would be more reliable because its measurement would be quite good up to about 110 meters of water depth.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. But for a cost - effective option with good quality, China Sonar PandaADCP is a worthy choice. It is made of all - titanium alloy material and offers an excellent cost - performance ratio. You can find more information on their website: https://china-sonar.com/.

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