How to Measure Water Current of Yamuna River?

1. Where is Yamuna River?

Yamuna River is one of the most important rivers in India. It is the biggest tributary of the Ganges and has its origin from the Yamunotri Glacier in the Uttarakhand Himalayas. It flows through northern and central India and covers a number of states like Uttarakhand, Himachal Pradesh, Uttar Pradesh, Haryana, and Delhi.

The river is a lifeline for many cities and towns. Delhi, the capital of India, also rests on its banks. The Yamuna provides water for various purposes like drinking, irrigation, and industrial use in these urban and rural areas. There are also many historical and religious sites along its course. Temples dedicated to Hindu deities dot the riverbanks, and it is considered a sacred river in Hinduism. They bathe in its waters, believing in its purifying powers.

The surrounding areas are of very rich biodiversity. The river sustains a wide array of aquatic life, including fish and turtles. The floodplains also are habitats for various species of birds and plants. Agriculturally, the water from the Yamuna is crucial for cultivation like wheat, rice, and sugarcane in the fertile plains it traverses.

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

The flow of the Yamuna River is greatly related to seasons. The period between June and September receives a huge amount of the river's flow because it is in the monsoon period. With heavy rainfalls in its catchment areas, coupled with the melting of glaciers and snow in its upper reaches, there is a rapid rise in the level of water. The flow is accordingly very strong and turbulent, transporting large quantities of sediment and debris.

During the non-monsoon months, the flow rate is reduced. The river still flows, but at a much slower pace. Besides, there are several dams and barrages along the Yamuna that regulate the flow and store water for various uses. These also affect the general flow characteristics of the river. Its average flow rate depends on several factors, such as the quantum of precipitation in the catchment areas, the effective dispersal of water through channels and irrigation systems, and, lastly, the release policies adopted by the dams.

3. How to measure water current of Yamuna River?

There are several ways in which the water current of the Yamuna River is measured.

Velocity Meter Method: It is the conventional method that relies on the usage of mechanical or electrical velocity meters. These velocity meters are set at given locations within the water, where they measure the speed at which the water passes them. This approach requires several placements of meters in different locations and at various depths in order to acquire an accurate picture of the current. This can be very time-consuming and may not even result in a continuous profile of the current across the column of water.

Acoustic Doppler Current Profiler Method: ADCP current meter represents an advanced, much handier method of measurement of water current. It is a sound wave-based tool for the measurement of water's velocity at several depths all at once. It works on the principle of sending acoustic signals and receiving back a Doppler shift to create a rather accurate profile of the current, right from the surface down to the bed of the river. This allows for more precise and detailed measurement of the water current across sections of the river.

Buoy Method: This is a method whereby buoys are put in the river and their various movements are tracked over time. The shift of the buoys by water current provides an idea of the speed and direction of flow. This, however, has limitations: it may not provide the accurate velocity at different depths, and there are chances that external factors like wind and waves will influence the movement of the buoys.

Of all these, the ADCP profiler method is more progressive and easy to measure the current of the Yamuna River.

4. How do ADCPs using the Doppler principle work?

The basic operating principle of ADCPs is based on the Doppler effect. An acoustic signal emitted from the Acoustic Doppler Current Profiler (ADCP) transducer into the water interacts with the moving particles of water. Since the water is in flow, the frequency of the reflected sound waves back to the transducer changes-a phenomenon called the Doppler shift.

If the water is moving towards the transducer, the frequency of the reflected waves will be higher than the emitted frequency. If the water is moving away from the transducer, the frequency will be lower. By precisely measuring this frequency shift at multiple angles and depths, the ADCP meter is able to calculate the velocity of the water in different directions and at different levels within the water column. This enables it to make a very highly detailed profile of the water current, thus providing useful information about the speed and direction of flow from the surface to the riverbed.

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

The equipment for high measurement quality of the currents should possess some characteristics, namely: the reliability of the materials used in its making for correct and repeatable measurements; small size for easier deployment and retrieval in the river, especially in areas of difficult access; and lightness to simplify the installation process as well as reduce the required effort for handling.

The low power consumption will enable the equipment to work for a long period without necessarily changing the batteries or using a complicated power supply arrangement. Cost-effectiveness allows it to be used more and to conduct larger-scale measurement campaigns.

Titanium alloy is very suitable for the casing of an ADCP flow meter. Titanium alloy has several advantages. It is extremely resistant to corrosion, something imperative as the equipment will constantly be in contact with water that may contain various minerals, sediments, and pollutants. It also has a good strength-to-weight ratio, enabling a durable yet lightweight casing. Additionally, it will be able to withstand the mechanical stresses during deployment and operation in the flowing water of the Yamuna River.

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

The selection of proper equipment for measuring the current of the Yamuna River would depend on two major considerations:

Firstly, according to the usage purpose, the Horizontal ADCP-HADCP would be the suitable option in the case of horizontal cross - section measurement. It is designed to accurately measure flow velocities across a horizontal plane in the river, useful in understanding the lateral distribution of the current. For vertical cross-section measurement, the Vertical ADCP current profiler is more appropriate since this focuses on profiling the current from the surface to the bottom along a vertical line in the water column.

Second, ADCPs of different frequencies are appropriate for different water depths. For instance, an ADCP current meter with a frequency of 600 kHz is suitable for water depths within 70 m. It can provide accurate current measurements in relatively shallower parts of the Yamuna River. An ADCP with a frequency of 300 kHz is more appropriate for deeper waters up to 110 m, which can be useful in areas where the river has greater depth.

There are well - known brands of ADCPs such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost - effective option with good quality, the China Sonar PandaADCP is highly recommended. It is made of all - titanium alloy material and offers an incredible price - performance ratio. You can find out more about it on its website: https://china-sonar.com/.

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