How to Measure Water Current of the Balonne River

1. Where is the Balonne River?

The Balonne River is a major watercourse in Queensland, Australia, part of the Murray - Darling Basin, with origins in the Carnarvon Range. It cuts through sprawling plains and farming lands in Australia.

This river is an essential source of water for the local communities around it. The local agricultural activities, such as cotton and wheat farming, depend on the water from the Balonne River for irrigation. Along its banks, there are also small towns and rural communities. The river is home to a variety of aquatic life, including fish species like yellowbelly, which is popular among anglers. The riparian zones of the streams and rivers will support diverse vegetation, housing numerous bird species and also other wildlife such as wallabies and kangaroos.

Culturally, Balonne River is important for the Indigenous Australians. Quite often, the river finds a place in their Dream Time stories and traditional knowledge to connect themselves with the land. European settlers, too, found a source of water supply and a means of transportation in it.

2. What is the nature of flow in the Balonne river?

The flow in the Balonne River is extremely variable. The general climate of Australia, characterized by its periodic cycles of drought and heavy rainfall, significantly affects the flow of the river.

During the wet season, it is usually from December to March in the region, there is a considerable rise in its flow. The water levels go up, and it is very strong. This may be because of the heavy rains that fall in its catchment area. The increased flow carries along sediments and nutrient deposits downstream, which makes the floodplains end up rich and vegetated.

During the dry season, from April to November, the flow rate decreases. Prolonged droughts severely affect the flow of the river, and at times the flow is very low or even the drying up of parts of the river. Some of the main factors include the quantum of rainfall in its upstream catchments, the topography of the catchment area that dictates the catchment and discharge of water, and the consumptive use by the Riparian communities for agriculture and domestic use.

3. How to measure water current of the Balonne River?

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

Method of Velocity Meter

This traditional approach relies on mechanical or electronic velocity meters. These meters are placed at specific points in the water to measure the speed of the water passing by. However, to obtain a comprehensive understanding of the current, multiple placements at different locations and depths are necessary. This can be quite 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 method of water current measurement is a little more advanced and efficient. The use of sound waves makes the simultaneous measurement of the velocity of water at different depths possible. It emits an acoustic signal, then analyzes the Doppler shift of the reflected signals to create a current profile from the surface down to the riverbed. This therefore gives the possibility of much more precise and detailed measurement of the water current across various sections of the river.

Buoy Method

In this method, buoys are placed in the river and their movements tracked over time. The displacement of the buoys due to the water current gives an indication of the speed and direction of the flow. However, this method has limitations. It may not provide accurate velocity measurements at different depths and can be affected by external factors such as wind and waves, which can influence the movement of the buoys.

Among these, the ADCP flow meter method is an advanced and convenient method for the measurement of the water current of the Balonne River.

4. How do ADCPs using the Doppler principle work?

The operating principle behind ADCPs is based on the Doppler effect. A transmitting acoustic signal from the ADCP meter transducer into the water causes interaction with the moving water particles. Because the water is in flow, the frequency of the reflected sound waves back to the transducer changes; this is 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 current profiler calculates the velocity of the water in different directions and at different levels within the water column. It can thus obtain a very detailed profile of the water current, with important information about the velocity and direction of flow from the surface to the bed of the river.

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

For high-quality measurement of the Balonne River currents, the measuring equipment should have certain characteristics. The materials used in its construction need to be reliable to ensure accurate and consistent measurements. A small size is beneficial as it allows for easier deployment and retrieval in the river, especially in areas with difficult access. The equipment should also be lightweight to simplify the installation process and reduce the effort required for handling.

Low power consumption is very critical for long operation without replacement or replenishment of batteries and with no complicated power supply configuration. Cost-effectiveness due to the ability of widespread application and larger-scale measurement campaigns.

In regard to casing material for ADCP meter, a perfect option is titanium alloy. Some major advantages of the application of titanium alloy include the following:. This material is highly resistant to corrosion, which is essential because the equipment is always in contact with water that could have a variety of minerals, sediments, and pollutants. It also has a good strength-to-weight ratio, allowing for a strong yet light casing. It will also be able to resist mechanical stresses during deployment and operation in flowing water.

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

In the selection of the right equipment for measuring the current of the Balonne River, two major factors should be considered.

Depending on the usage purpose, for horizontal cross - section measurement, the Horizontal ADCP is the suitable option. The horizontal ADCP is one type of ADCP suited for measurement across a horizontal plane in the river, to realize an accurate flow velocity necessary in understanding the lateral current distribution. In the case of vertical cross-section measurements, the Vertical ADCP will be more appropriate, mainly focusing on profiling from top to bottom along a vertical line in the water column.

Second, different frequencies of ADCPs suit different water depths. For instance, the ADCP profiler frequency of 600 kHz is suitable for water within 70 m depth. It will provide an accurate current measurement in the relatively shallow parts of the Balonne River. A 300 kHz-rated ADCP is more suitable for waters as deep as 110 m and will be helpful in places where the river is much deeper.

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/.

Tsangpo River is the mighty river originating on the Tibetan Plateau. Being a component of the high-altitude ecosystem of Tibet, the river originally starts from near Mt Kailash and Lake Manasarovar.

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