How to measure water current of Dadu River?

1. Where is Dadu River?

The Dadu River is a major river in China. It lies in Sichuan Province and forms part of the Yangtze River system. The river meanders through mountainous regions with breathtaking scenery, including deep gorges and lush forests.

On its banks are many towns and villages. The river has had a profound impact on the local culture and economy. It has been a crucial transportation route in history, facilitating the movement of goods and people. The local people also rely on it for water supply and agricultural irrigation. The Dadu River's waters support a diverse range of flora and fauna. The surrounding landscapes host unique plant species and different wildlife, including fish, birds, and small mammals.

2. What is the flow rate of the Dadu river?

The flow rate of the Dadu River varies with seasons. It has a huge volume during the rainy season, normally from June to September, due to heavy rainfall and snowmelt from the upstream mountains. In this period, the flow of the river is powerful and rapid, and the flow velocity reaches a relatively high value with substantial discharge.

During the dry season, from October to May, it slows down. The river goes down and becomes mild, with average flow velocities from 0.5-1.5 meters per second during the dry season. Depending on a section or influence of upper reaches regulation facilities, it may provide for a variation in discharges from 50 to 200 cubic meters per second.

3. How to measure water current of Dadu River?

There are several methods to measure the water current of the Dadu River.

The velocimeter method: This is traditionally done by using mechanical and electrical velocimeters. Instruments used are placed at different deep and varied locations in the river. The speed of flow of water at these points being directly measured, an idea about the current is obtained. However, this requires a lot of labour and time, especially when trying to cover a wide area in the river.

Acoustic Doppler Current Profiler (ADCP) method: This is a more advanced and efficient way. It emits acoustic signals into the water column and analyzes the Doppler shift of the reflected waves. Thus, it can give the velocity of water at various depths simultaneously. Compared with the velocimeter method, this ADCP profiler method will be able to provide a more comprehensive detailed view of the flow conditions in the river in a relatively short time.

Buoy method: Buoys with sensors or tracking devices are set on the surface of the Dadu River. From the movement of the buoys over a certain period of time, an approximation of the surface current speed and direction can be estimated. This method, however, concerns the surface flow and may not give a true representation of the conditions at greater depths.

Of the methods listed in the above text, an ADCP meter is presently a more progressive and handier way to measure the water current of the Dadu River since it provides the most detailed multi-depth data with relatively less effort.

4. How do ADCPs using the Doppler principle work?

ADCPs are based on the principle of Doppler. They emit a frequency of acoustic pulses in water. If these sound waves are reflected by moving particles of water-sediment particles or small organisms-the frequency of the reflected waves shifts. This is the so-called Doppler shift.

If the particles are moving towards the ADCP flow meter, the reflected frequency is higher than the emitted frequency, while if they are moving away, it is lower. By precisely measuring this frequency shift, considering the angle at which the acoustic signals were emitted and received, the ADCP can calculate the velocity of the water at different depths. Multiple transducers on the ADCP are usually mounted in different orientations to measure the flow velocity in different directions, including both horizontal and vertical components. This enables the creation of a detailed profile of the water current within the river.

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

Such measurements of the currents of the Dadu River should possess certain characteristics, including resistance and reliability of the materials applied in the making of the measuring devices. The equipment operating in this kind of environment needs to be capable of resisting mechanical impacts resulting from floating debris or sudden changes in water temperature and quality.

Secondly, it must have a small size, lightweight, and low power consumption. A compact design makes its deployment and retrieval easier, which is of particular importance for this region, where the access to the river may be somewhat complicated because of the topography or due to poor infrastructure. Low power consumption would mean the equipment can be operable for longer without any replacement of batteries or any external source of power.

It is also very important to consider cost when doing large-scale measurements. When it comes to ADCPs, titanium alloy is really an excellent option for casing material. It has many great advantages, very good corrosion resistance, long - time immersion in river water will not make any big deal to the probe. It is also strong and durable, able to resist mechanical stresses such as those caused by water currents and accidental impacts. Besides, it is relatively light compared to a lot of other metals, which makes it a good material for equipment applied in water current measurement.

6. How to Choose the right equipment for current measurement?

While choosing the right equipment for measurement of the current of the Dadu River, consider the following. First, for the horizontal cross-section measurement of the flow of the river, the Horizontal ADCP current profiler or HADCP will be suitable. The HADCP is specifically designed to measure with accuracy the flow characteristics in the horizontal plane. On the other hand, Vertical ADCP is more suitable for vertical cross-section measurement as it provides detailed information on flow at different depths along a vertical line.

Besides, different frequencies of ADCPs are suitable for different water depths. For example, an ADCP with a frequency of 600 kHz is well-suited for water depths within 70 meters. It can provide clear and accurate measurements in the relatively shallower parts of the Dadu River. Meanwhile, an ADCP with a frequency of 300 kHz is more appropriate for water depths up to 110 meters, enabling effective measurement in the deeper sections of the river.

There are well - known ADCP current meter brands like Teledyne RDI, Nortek, and Sontek. However, for a cost - effective yet high - quality option, the China Sonar PandaADCP is worth considering. It is made of all - titanium alloy material, ensuring its durability and reliability and offering an excellent cost - performance ratio. You can find out more about it on its official website: https://china-sonar.com/.

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