How to measure water current of Brahmaputra River?

1. Where is Brahmaputra River?

Originating from the Angsi Glacier in Tibet, China, the Brahmaputra River flows through Tibet Autonomous Region into India and then Bangladesh. It cuts across high mountains, fertile plains, and tropical rainforests along its course.

The Brahmaputra is the lifeline for millions of people, providing water for irrigation, transportation, and power generation. It has a very rich variety in flora and fauna, hence is an important ecological hotspot.

There is great cultural importance of the river as well. The river has a lot to do with many religious and historical spots; hence, the banks are dotted with ancient temples and shrines.

2. What is the flow rate of the Brahmaputra river like?

The flow rate in the Brahmaputra River significantly differs over the year. During the monsoon-from June to September-heavy rainfall and snow melting in the Himalayas create an enormous input into this river. During such periods, it is really possible for the flow rate values sometimes to be more than several tens of thousands of cubic meters per second.

The flow rate significantly decreases during the dry season from November to May. Still, even in these arid months, the discharge of the Brahmaputra is great enough to supply critical water resources to the surrounding areas.

Construction of dams, creation of reservoirs, and changes in land use also regulate the Brahmaputra's discharge. In addition, these human activities may provide the essential modulation in the hydrology and ecology of the river.

1. How to measure water current of Brahmaputra River?

It is crucial to measure the water current of the Brahmaputra River in relation to the dynamics of this River, flood management, and environmental conservation.

Traditional methods

The conventional methods of measuring currents in a river are by current meters. These instruments are submerged in water and directly measure the velocity of flow. Still, this, being one of the ways of measurement, is very time-consuming and requires a lot of labor, which may be a little difficult in the case of big rivers like Brahmaputra.

The other conventional method is to have floats or dyes to observe its movement. By releasing a float at a known location and tracing its movement downstream, the speed of the current can be estimated. But this is a less accurate method. It is also vulnerable to wind and other environmental factors.

Modern technologies

The advances in measuring river currents have produced advanced technologies in recent years. Among those, one is Acoustic Doppler Current Profilers, which surely proved a more efficient and accurate way of measurement of water currents.

Why ADCP is a better choice?

The ADCP is based on the Doppler principle, in which it undertakes the direct measurement of the water particle velocity. It sends out sound waves and, from the frequency shift of the reflected waves analyzed, an acoustic doppler velocity meter can spot the speed and direction in which the water flow is moving at each separate depth. This enables a thorough understanding of the current profile of the river.

By far, acoustic doppler flow meter have the advantage of measuring the current in a wide area with rapid and accurate means without manual operation. It is also able to provide continuous data, thus it monitors in real time river conditions.

3.1 How do the Acoustic Doppler Current Profiler(ADCP) using the principle of the Doppler work?

ADCP current meter work by emitting a sequence of sound pulses into the water. These pulses interact with the particles moving with the water, which creates a frequency shift in the reflected waves. The frequency shift detected is used by the ADCP to determine the velocity of the particles of water.

The ADCP current profiler generally consists of a transducer that transmits and receives the sound waves, a data logger that does the recording of measurement, and software to analyze the measured data. The transducer can be mounted on a boat, on a bridge, or on any fixed structure in the river and pointed in various directions to measure current in different dimensions.

3.2 What's needed for high-quality measurement of Brahmaputra river currents?

The following various factors should be considered in order to obtain high-quality measurement for the currents of the Brahmaputra River.

Material reliability

The casing of ADCP flow meter needs to be fabricated using a durable corrosion-resistant material. So, a good choice would be to have an alloy of titanium metal due to its high strength, low weight, and good resistance to corrosion. This will also be able to cope with the demands put by the stressful environment that the Brahmaputra River comes under.

Small size and lightweight

Lightweight and compact in size, the ADCP meter will be easily transportable and deployable. This factor will help reach those remote locations in the interior parts of the Brahmaputra for current measurements.

Low power consumption

Long-term current monitoring in rivers requires low power consumption. The designing of the ADCP profiler should be in a way that they run on low power to reduce frequent changes of batteries or looking for an external source of power.

Economical compatibility

Cost is again a problem in selecting the measurement equipment. ADCP instrument are to be cost-effective and should give good value for the money spent. This can ensure its usage widely and hence, cover more on the monitoring of the river currents.

3.3 How to select the right equipment for current measurement?

For the measurement of the currents of the Brahmaputra River, some criteria are to be considered in selecting the equipment.

Identify the measurement purpose

The first task is establishing the purpose of measurement. In case the section of the river needs to be measured horizontally, then the horizontal ADCP is what shall be used. The HADCP is specially designed for the measurement of current velocity in a horizontal plane; thus, it can be of great use in giving comprehensive details relative to flow patterns and velocities across the river.

If the vertical current profile is the measurement of interest, then a vertical ADCP is the better choice. Vertical ADCP can measure the current velocity at a number of different depths, providing a better understanding of the vertical structure of the river's flow.

Choose the Right Frequency

Performance depends directly on the frequency of the ADCP. A higher frequency is used in shallower waters and can yield high resolution in the measurement of fast-flowing currents. A low frequency suits deeper waters and can penetrate through sediment and other obstacles.

For measurement in the Brahmaputra River, an ADCP operating at 600 kHz can work correctly up to a depth of 70 meters, and further extension up to a depth of 110 meters is possible using an ADCP operating at 300 kHz.

Consider cost and quality

Finally, the financial costs associated with an ADCP in its selection have to be considered. There are different ADCP brands currently available on the market, and it is essential that a trustworthy and reasonably priced one is selected.

One of the recommended brands that deal in quality China Sonar ADCP made of all-titanium alloy material is PandaADCP. PandaADCP are also famous for their great performance, reliability, and affordability. The website of PandaADCP is [https://china-sonar.com].

In other words, there is an urgent need for measurement of the water current of Brahmaputra River for a greater understanding of the complex hydrology of this river and for effectual flood management and environmental conservation. Compared to earlier methods of measurement, the ADCP were advanced and convenient ways to measure river currents. An appropriate ADCP could be selected for high-quality measurements of the currents in the Brahmaputra River based on material reliability, size, weight, power consumption, and cost.

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