How to measure water current of Krishna River?

1. Where is Krishna River?

The Krishna River is one of the biggest rivers in the Indian subcontinent. It originates in the Western Ghats near Mahabaleshwar in Maharashtra, India. Flowing eastward across the Deccan Plateau, it traverses through the states of Maharashtra, Karnataka, Telangana, and Andhra Pradesh.

This river is a lifeline for millions of people. Along its banks, there are a number of cities and towns. One such bustling city in Andhra Pradesh is Vijayawada. The river has played an important role in the development of these urban centers by providing water for drinking, irrigation, and industrial purposes. The landscape is interspersed with both fertile plains, wherein agriculture flourishes because of the waters, and also arid areas, which equally receive sustenance from the same.

The Krishna River abounds in cultural and religious significance as well. The river is sacred in Hinduism, with a number of temples and pilgrimage places along its course. Apart from these, several annual festivals and religious congregations held around its banks attract a deluge of devotees while adding colors of vibrancy with spiritual feel to the realm. Water in this river has always figured in folklore and mythology that form part of beliefs among local people as if gods and goddesses emanated their origin and its flow.

2. What is Krishna River like in Flow rate?

Krishna River is significant to the agricultural and economic welfare of the regions through which it passes. The river acts as a great source of irrigation waters, thus enabling the irrigation of a wide range of crops like rice, sugarcane, and cotton.

The Krishna River has variable discharges. The flow in the river increases extensively during the monsoon period that usually prevails over India during the months of June to September. Heavy rainfall over its catchment area raises the level of water and often gives a high flow velocity. The river can contain a large volume of water, and flooding in low-lying areas is common. During non-monsoon months, the flow rate decreases. Reservoirs and dams along the river help in controlling the flow, storing water in the wet season and releasing it in the dry seasons to cater to the demands in agriculture, domestic use, and industry.

The average flow rate is affected by the amount of rainfall in the Western Ghats, its source region; the efficiency of water diversion through canals and irrigation systems; and the water storage and release policies of the various dams. In general, its flow is a critical determinant of the ecological and economic stability of the regions it serves.

3. How to measure water current of Krishna River?

There are several methods for measuring the water current of the Krishna River, including the following.

Velocity Meter Method: This conventional technique utilizes conventional devices such as current meters. These usually come in mechanical or electronic forms and are installed at particular points in the river. They measure the speed of water that passes by their point of installation. However, this method requires the manual deployment and retrieval of the meters at different locations and depths to get an overall understanding of the current. It is a time-consuming process and may not provide a continuous profile of the current throughout the water column.

Acoustic Doppler Current Profiler (ADCP) Method: The ADCP current meter is an advanced and efficient way of measuring water current. This makes the product capable of measuring the instantaneous speed of water at different water depths simultaneously by using a range of sound waves. Measuring the Doppler shift from an acoustic signal emitted and received, it can generate the details on a current profile from the water surface to the riverbed. This allows for precise and comprehensive measurement of water current across different sections in the river.

Buoy Method: Under this method, buoys are placed in the river. The movement of the buoys due to water current is tracked over a length of time. Their displacement provides an idea about the speed and direction of flow. This, however, has its inadequacies. It does not give precise velocity at a varied depth. Moreover, wind and waves may affect it, transferring the buoy with them.

Out of these, ADCP current profiler is relatively more advanced and handy technique for the measurement of Krishna River's water current.

4. Working of ADCPs based on Doppler Principle

The basic operating principle of ADCPs is based on the Doppler effect. When an acoustic signal is emitted from the ADCP profiler transducer into the water, the sound waves interact with the moving water particles. Since the water is in flow, the frequency of the reflected sound waves back to the transducer changes-a phenomenon well known as 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, 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 create a detailed profile of the water current, which gives great insight into the speed and direction of the flow from surface to riverbed.

5. What is required for high-quality measurement of Krishna river currents?

Such a measurement of Krishna River currents requires equipment with certain characteristics for high - quality measurement. The materials used in the making of the measuring device should be reliable. Small size is preferable for easy deployment and retrieval in the river, especially in areas that are difficult to access. The equipment should not be heavy as it simplifies the installation process besides reducing the amount of effort required in handling.

Its electric consumption should be minimal so as not to limit operation time before the need to replace the batteries or take a large complex system of power; cost-effectiveness is also desirable to spread its use in more projects and measurement campaigns on larger scales.

This ADCP flow meter casing should also be fabricated in titanium alloy due to various benefits. It is highly resistant to corrosion, which is important because the equipment is always in contact with water that may contain a variety of minerals, sediments, and pollutants. It also has a good strength-to-weight ratio, which allows for a strong yet lightweight casing. Finally, it will be able to resist the mechanical stresses during deployment and operation in the flowing water of the Krishna River.

6. Selection of Correct Equipment for the Measurement of Current

The selection of the right equipment for current measurement in the Krishna River will depend on the following two factors.

The purpose of usage-for horizontal cross-section measurement, the Horizontal ADCP is suitable. That's by the design to measure with better precision the flow velocities over a horizontal plane in the river in order to understand the current lateral distribution. In case vertical cross-section measurement is intended, the Vertical ADCP current profiler fits even more accordingly, since it's purpose is to profile from top to bottom the current profile along a vertical line of the water column.

Different frequencies of ADCPs are suitable for different water depths. For example, an ADCP current meter at a frequency of 600 kHz is suitable for water depth within 70 m; it can provide accurate current measurements in relatively shallower parts of the Krishna River. An ADCP with a 300 kHz frequency is more suited for deeper waters up to 110 m, which can be useful when the river has greater depth in certain areas.

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.