Measurement of the Chi River Water Current

1. Where does the Chi River belong?

The Chi River belongs to Thailand. It is also a tributary of the Mekong River. It originates from the eastern part of the country. It flows through the entire region into a mix of agricultural areas, forests, and small villages.

The river itself is significant in terms of local agricultural activities. It waters the irrigation of crops, such as fruits, vegetables, and different types of grains. Local communities also depend on the river for fish catches and transportation. The banks of the river provide a home for numerous wildlife, such as birds of different species, reptiles like water monitors, and amphibians. The floodplains and wetlands along the river are very important to maintain ecological balances, providing breeding and feeding areas for many species.

2. What is the flow rate of the Chi River like?

The flow rate of the Chi River is subject to seasonal and climatic variations. Thailand's wet season, usually from May to October, brings heavy rainfall to the river's catchment area. During this period, the river's flow rate significantly increases. The river becomes fuller and can carry a large volume of water.

It tapers during the dry season, from November through April, but still retains a base flow that is supportive of aquatic life and capable of supporting local activities like fishing and some limited transportation. The average flow rate can thus range from a few tens of cubic meters per second during the dry season to several hundred cubic meters per second during the peak of the wet season.

3. How to measure water current of the Chi River?

Velocity Meter Method

Traditional methods make use of mechanical or electronic velocity meters. These instruments are installed at discrete points along the river and provide a direct measurement of the local velocities at their installation points. However, to be representative of the general water current, several partial measurements have to be made across the river section at different depths. This can be very labor-intensive and time-consuming for a long, variable river like the Chi River.

ADPC Current Profiler Method

A more sophisticated and opportune method to measure water currents is using the ADCP current meter. Employing the reflection of sound waves, the ADCP detects the motion of water particles. Capable of simultaneously measuring the velocity of water at different depths through the emission and analysis of the Doppler shift of acoustic signals reflected back to it,. This gives a very accurate profile of the water current and therefore a better representation of the flow conditions across the whole river. ADCPs can be fitted to boats-if the river is navigable-bridges-if available-and buoys for continuous monitoring.

Buoy Method

The buoy method involves placing buoys in the river that are fitted with sensors to measure the movement of water around them. They can float in the surface and sometimes give an indication of the current at the surface. They may not capture the full complexity of the water current as accurately as the other methods, especially for showing the variation in velocity with depth.

Among these methods, the ADCP current profiler stands out as a more sophisticated and efficient option for measuring the water current of the Chi River.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of Doppler. When an ADCP flow meter sends an acoustic signal into the water, the sound waves travel through the water and interact with the moving water particles. Since the water particles are moving, the frequency of the reflected sound waves shifts due to the Doppler effect.

If the water particles are moving towards the ADCP meter, then the reflected wave frequency is higher than that emitted. If the water particles are moving away from the ADCP, then the reflected wave frequency is lower. By accurately measuring this shift in frequency, the ADCP can determine the velocity of the water particles at various depths.

These individual velocity measurements from the ADCP profiler are then combined at various depths to develop a complete profile of the water current. This allows for a detailed realization of how the water is flowing, not only at the surface but throughout the vertical section of the river.

5. What's needed for high - quality measurement of the Chi river currents?

Such measurement of the Chi River currents would require certain characteristics of equipment for high-quality measurement.

The equipment must be highly materially reliable. The equipment should be able to bear the severe conditions of the aquatic environment in terms of contact with water, sediment, and temperature fluctuation. Flow in the Chi River can be variable, and during high flow, it can carry debris; thus, the equipment must be durable.

It also would be desirable to reduce the size and weight to a minimum and limit the power consumption. A compact, lightweight device is easier to manipulate and deploy whether from a boat or attached to a buoy. Low power consumption means that the equipment can function for longer periods of time without requiring frequent replacements of the batteries or access to a continuous power source.

This is all about cost-effectiveness. It is cheaper, so one can use as many measurement devices as one wants in order to monitor the river thoroughly.

For example, regarding the casing of the ADCP meter, titanium alloy is an excellent choice. The corrosion resistance of the titanium alloy is high, which is something important while dealing with water bodies such as the Chi River, where the equipment will always be in contact with water and likely corroding elements. It is strong, sturdy, and resistant to the different physical impacts, hence to changes in pressure that may happen during deployment and operation. However, besides all these factors, titanium alloy also has relatively low density to help with the overall purpose of keeping the equipment light in weight.

6. How to Choose right equipment for current measurement?

While choosing the right piece of equipment for measuring the current of the Chi River, several factors are to be considered.

Based on the Purpose of Use

In case the intention is to measure the horizontal cross-section of the river current, then a horizontal ADCP flow meter would be an appropriate choice. HADCPs are designed in a manner to give correct measurements of the water flow in the horizontal plane that helps explain the lateral movement of water across a particular section of the river.

If the focus is to measure the vertical cross-section of the river current, then a vertical ADCP current profiler should be selected. The vertical ADCP can accurately measure the water velocity at each depth, providing a detailed profile of how the water is flowing vertically within the river.

Based on Frequency

The frequency depends on the depth of the water in the Chi River. For water depths up to 70 meters, a 600 kHz ADCP would normally be an appropriate option. The 600 kHz frequency would provide good resolution and accuracy for measuring the water current in such moderately shallower waters.

For deeper waters, such as those over 70 meters going up to around 110 meters, the better one to use would be the 300 kHz ADCP. The low frequency of 300 kHz will be able to penetrate deeper in water and still manage to provide reliable measurements of the water current.

There are renowned ADCP current meter brands, including Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost - effective option with excellent quality, the China Sonar PandaADCP is worth considering. It is made of all - titanium alloy material, ensuring durability and reliability. With its remarkable cost - performance ratio, it provides a great alternative for measuring the water current of the Chi River. You can find more information about it on its official website: https://china-sonar.com/.

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