How to Measure the Water Current of the Irrawaddy?

1. Where is the Irrawaddy?

The Irrawaddy River provides the lifeblood of Myanmar-Burma. It is the greatest and most important river in the country, cutting across the heart from north to south in this Southeast Asian nation. Originating from the confluence of the Mali and N'mai rivers in northern Myanmar near the border with China, it meanders its way southward for over 2,170 kilometers.

The Irrawaddy flows through very different terrains-from the mountainous areas in the north down to the elongated delta in the south. The broad alluvial plains along both banks give place to rich agricultural lands hosting a carpet of emerald-green paddy fields as far as the eye can see. Besides being a source of life for man, the river also hosts a great variety of flora and fauna. Mangrove forests line the edges of the delta, providing a vital breeding ground for many species of birds, fish, and crustaceans.

The Irrawaddy culturally means a lot: the epicenter of thousands of years of Myanmar's history and civilization, many cities, and ancient religious sites dot its banks. It is a veritable artery wherein innumerable watercraft in the form of boats and barges navigate and ply their goods up and down the stream, carrying people and goods across. It is also a very important source of water for domestic use, irrigation, and fishing-something that has kept the livelihoods of millions afloat.

2. What is the Nature of Flow Rate in the Irrawaddy?

The flow rate of the Irrawaddy is highly variable. During the wet season, generally from May until October, the river retains an extremely high discharge. Heavy rainfall throughout the catchment area, most of which consists of mountainous regions in the north, causes the river to swell. The current can forceful and the volume of water can increase much.

This goes down during the dry months, starting in November through to April of the next year. The width of the river goes down, with the water level going low. The flow becomes very subtle, with shallow waters at times and in certain parts of the river. The flow varies along the length of the river, with the average recorded flow also at different points. This would mean that at the higher reaches, it could run relatively faster owing to the steep gradient it has, while in the broad delta area, it would be very slow as the river spreads and deposits sediment.

Activities induced in humans that affect the Irrawaddy flow of water include construction of dams and water extraction for irrigation. Such interferences can have consequential effects quite seriously on the natural pattern of flow and overall health of the ecosystem of the river.

3. How to Measure Water Current of the Irrawaddy?

There are various means of measurement for Irrawaddy water current. Conventionally, it may be measured by a current pole. This consists of a very long pole with markings on it, immersed in the water. The deflection that the pole has from the vertical will give a rough estimate of the surface current speed.

Another method may be the use of floats. A float is released in the river and its time to travel for a known distance is observed, which allows estimating the velocity of the current. However, these methods are quite simple and probably cannot provide comprehensive knowledge about the water current at different levels.

A more sensitive way is the use of acoustic Doppler current profilers.

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

ADCP profiler is based upon the principle of the Doppler effect. The instrument sends acoustic pulses into the water. These pulses scatter off suspended particles and other materials in the water. Because the water is moving, the frequency of the acoustic signal reflected back changes.

ADCP profiler based upon the principle of the Doppler effect. The instrument sends acoustic pulses into the water. These pulses scatter off suspended particles and other materials in the water. Because the water is moving, the frequency of the acoustic signal reflected back changes.

This frequency shift is measured by the ADCP current profiler and, by using the Doppler formula, calculates the velocity at depth. The pulses of the ADCP doppler come out in many directions and at various frequencies, enabling it to give an extremely accurate profile of the water current throughout the column of water. This yields a much more accurate, even detailed understanding of the current structure in the river than traditional methods.

3.2 What is required to measure the Irrawaddy currents with good quality?

Reliability of the equipment for high - quality measurement of the Irrawaddy currents: violent monsoon currents, high sediment load during the wet season, and possibly exposed to all kinds of weather - the measuring devices must be strong enough to operate under such conditions.

The equipment must be compact and lightweight. This is important for ease of deployment, especially from remotely accessed areas along the river or from boats. The consumption of power should be low so that the equipment operates over a long time without frequently changing batteries or having an external power source. Cost-effectiveness is another crucial factor, while large-scale measurements may be essential for understanding the dynamics of the river better.

The application of casing made of titanium alloy is advantageous in ADCP current meter. Indeed, titanium alloy has a very high resistance to corrosion, which is of the essence in a water-rich environment like the Irrawaddy. Besides, the alloy also offers strength, thus being durable in supporting the physical forces exerted against it by the river current and possible impacts. Its light weight also provides more convenience during transportation and installation.

3.3 How to Choose the right equipment for current measurement?

The type of equipment that would be used for measurement of the Irrawaddy current would have to depend upon the exact nature of measurement. In general, horizontal ADCP, or HADCP, is quite suitable for horizontal measurements across any section of the river. It gives an extensive view of the flow of the current in the horizontal plane of the flow and will help in understanding the overall flow pattern of the river.

For making vertical profile measurements, an upward-looking ADCP flow meter would be more appropriate for the current. The sensor could provide information on the velocity of the water in great detail at different depths, which is an important factor in studying stratification and mixing of the water column.

For the relatively shallower parts of the Irrawaddy, up to about 70 meters, a 600 kHz frequency ADCP might be sufficient. For deeper stretches, roughly up to about 110 meters, an ADCP meter with a frequency of 300 kHz would be appropriate.

There are well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option with good quality, the China Sonar PandaADCP is a great choice. It is made of all - titanium alloy, providing durability and resistance to the Irrawaddy's environment. It also offers an excellent price - performance ratio. You can visit https://china-sonar.com/ for more information.

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