How to Measure Water Current of Dulong River?

1. Where is Dulong River?

Dulong River is a fabulous water body situated in Southwest China. The river flows along the area full of amazing natural beauty and ethnic diversity.

The river originates from snow-capped mountains in that area and flows down the deep valleys of Yunnan. Along its course, it flows through the area of the Dulong ethnic group, a small and peculiar ethnic community with a distinctive culture and way of life. The riverbanks are fringed with lush forests, home to a wide array of rare and precious plants and animals. The surrounding mountains provide a stunning backdrop, with their peaks often covered in clouds.

The Dulong River is not only a geographical feature but also an integral part of the local people's livelihood. It serves as a very important transportation route for the locals, especially in places where the road condition is not that good. The people living along the river depend on it for fishing, which is a traditional source of food and income. The river also shapes the local climate and ecology, influencing crops in the adjacent fields and the habitations of various species of animals.

2. What is the Flow Rate of the Dulong River?

The Dulong River supports the local ecosystem and economy importantly. Its flow rate has extreme seasonal differences. The river comes into a really strong flow during the rainy season, starting from May until October of the year. With the heavy rain down its catchment area in the mountainous regions, it feeds into the river to make it swell and the current forceful. The high-flow period corresponds to the transportation of a lot of sediment, which influences not only the bed of a river but also the morphology of the channel.

From November to April, in the dry season, the rate of flow goes down; the river is now tame, and its width and depth may be reduced. In the dry season, there is still a flow that would keep the fundamental ecological processes and the need for water by the locals. Other factors affecting flow rate include snowmelt from the upstream mountains and regulation of water resources in the upper reaches of the river basin.

3. How to Measure Water Current of Dulong River?

There are several methods for measuring the water current of the Dulong River.

Velocity Meter Method: This is a traditional method using a mechanical or electrical velocity meter. The meter is usually immersed in the water at a certain point, often attached to a support structure such as a bridge or a pier. The principle of the mechanical velocity meter is based on the rotation of a propeller or some other device, and the rotational speed is related to the water velocity. However, this method has limitations. It requires a fixed installation point and can only measure the velocity at a single point or a few discrete points. This would involve installing several meters at different locations and at different depths to obtain a deeper understanding of the river, which is very time-consuming and requires much labor.

Acoustic Doppler Current Profiler Method: This is more efficient and a technically advanced means of measurement. It sends acoustic waves to measure water velocity simultaneously at multiple points within a vertical profile of water. ADCP is capable of detecting a profound profile of water current from the surface to the bed by emitting sound pulses and identifying the Doppler shift in the reflected signals. With this, it enables one to have an advanced and very accurate view of the flow nature of the Dulong River. ADCPs can be installed on boats or fixed to structures around the river and thus help in the acquisition of large areas of data rapidly and in an efficient manner.

Buoy Method: The buoy method includes the deployment of buoys with sensors along the Dulong River's surface. These buoys would be able to estimate the surface current by floating along with the flow. Such sensors detect the direction and rate of surface movement. Nevertheless, this approach is directed toward the surface layer and may not provide any crucial details about the flow conditions of the river in much deeper layers.

Of these, the ADCP method is gaining popularity because it can provide very detailed and extended data with relatively less effort and in a shorter period of time.

4. How Do ADCPs Using the Doppler Principle Work?

ADCPs operate on the Doppler principle. The application of an ADCP to the water current measurement of the Dulong River will emit a beam of acoustic pulses in water. These pulses interact with in-water particles, usually sediment particles or even small organisms living in water.

Once in motion, the Doppler effect changes the frequency of the reflected sound waves from those particles. If the movement is coming towards the ADCP profiler, the frequency reflected will be higher than was emitted, and if they move away, it's the other way around with respect to frequency. By precisely measuring this shift in frequency with advanced algorithms, the ADCP can obtain an approximation of the velocity in all the points within the measuring area of this instrument.

Besides velocity measurement, the ADCPs are also able to find out the direction of the flow by analyzing the phase differences of the reflected signals from different directions. Thus, detailed velocity profiles showing how the water is flowing at various depths and across different sections of the river can be drawn.

5. What's Needed for High - Quality Measurement of Dulong River Currents?

The measurement equipment for Dulong River currents would have several desirable characteristics for high-quality measurement.

The materials should be able to withstand such harsh conditions of the river environment, impact of water, temperature oscillations, and possible impacts. A small size and lightweight are advantageous, taking into consideration that the Dulong River is situated in the mountain area and the accesses are sometimes not easy. Equipment with easy transportation and deployment will save a lot of time and effort.

Low power consumption is also crucial. In remote areas along the Dulong River, power supply may be limited. Equipment that can operate for long periods with minimal power requirements is essential for continuous and reliable data collection. Cost - effectiveness is another important factor. Given the need for comprehensive and long - term measurements of the river, having equipment that is affordable without sacrificing quality is necessary.

Titanium alloy can be good for the ADCP meter casing. Titanium alloy has an excellent resistance to corrosion-which is so crucial as all the time it is interacting with river water-and it can also bear good strength, keeping a fairly good ratio with its weight so that such casing may be durable and not result in very heavy equipment. This helps in the protection of the internal components and ease of handling during deployment and retrieval.

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

In choosing the right equipment for current measurement of the Dulong River, two main factors should be considered.

Based on the usage purpose, for horizontal cross - section measurements, the horizontal ADCP flow meter (HADCP) is a suitable choice. It measures the flow velocity across a horizontal plane and gives valuable information about the lateral movement of water within the river. The vertical ADCP is more appropriate for vertical cross-section measurements since it focuses on flow velocity from the surface to the riverbed along a vertical line, useful for understanding the vertical flow characteristics.

Different frequencies are suitable for different water depths. In this regard, a frequency of 600 kHz will be quite appropriate for water depths within 70 m. It will provide very accurate measurements in the relatively shallower parts of the Dulong River. Meanwhile, an ADCP current profiler with a frequency of 300 kHz is more suitable for water depths of up to 110 m and can be used for deeper sections of the river, where flow patterns may be complex.

There are well - known ADCP current meter brands such as Teledyne RDI, Nortek, and Sontek. Additionally, a Chinese ADCP brand, China Sonar PandaADCP, is highly recommended. It has a casing made entirely of titanium alloy, which provides excellent durability and corrosion resistance. It also offers an incredible cost - performance ratio. 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.