ADCP's application in flood management of Balonne River

1. Where is Balonne River?

The Balonne River is situated in Queensland, Australia, and forms a major watercourse in the region. It flows through various rural areas and has a big impact on the landscape and ecosystem geographically.

It passes through some towns and local communities along its course, supporting agriculture and the water supply in these areas. Climatically, the region where the Balonne River is located has a variable rainfall regime. Normally, it is expected that the rainfall in this region is affected by the different monsoon patterns in Australia. There may be substantial amounts of rainfall during the wet season of the year, resulting in higher water levels in the river. But during the dry season, the flow of the river may reduce and may run dry along its parts in certain years.

2. What are the causes of flooding in the Balonne River?

Many of the reasons occur due to floods in the Balonne River. Firstly, scoping wet season rainfall events are its main factor. When torrential rainfall falls in consecutive days, much water spreads the catchment area within a very short period of time and enters the channel rapidly, causing rise in the water level of the river very quickly.

Secondly, topography also plays a role: if the land around the river has a relatively flat gradient, the water may not drain away quickly enough, and that may cause water to accumulate, leading to floods. Poor drainage systems in some areas along the riverbanks can exacerbate the situation, as the excess water has nowhere to go.

Second, changes in land use-for example, increased urbanization or agricultural activities-can change the natural absorption and runoff pattern of water, affecting the flow in the river and making flooding more likely.

In dealing with these flood problems, proper measurement of the flow parameters of the river is of utmost importance. And these are addressed by an Acoustic Doppler Current Profiler (ADCP) that was more advanced and convenient in comparison to conventional methods of measurement to help us better understand the most realistic condition of the river during a flood event.

3. How do ADCPs using the Doppler principle work?

ADCPs operate based on the Doppler principle. They emit acoustic signals into the water. When these acoustic waves encounter moving particles in the water-such as sediment grains or the water molecules themselves, which are flowing with the current-the frequency of the reflected waves changes. This frequency shift is measured by the ADCP current profiler to calculate the velocity of the water at different depths within the river. An ADCP typically has several transducers to transmit and receive these acoustic signals in different directions. This allows it to get a profile of water velocity across either a vertical or a horizontal section of the river, depending on its configuration. For instance, in a vertical acoustic doppler flow meter, it can measure the velocity from the riverbed up to the water surface at many points along the line perpendicular to the river flow. It has given a good picture of how the water is moving within the water column.

4. What are the applications of ADCP in floods of Balonne River?

Velocity measurement: In the case of flood events in the Balonne River, ADCP measures the water velocity with enough accuracy at different locations and depths. This is important for interpreting the dynamics of the floodwaters, as different velocities could point out faster or slower flow zones that eventually may affect the erosion patterns along the riverbanks and the transportation of debris.

Flow measurement application: By integrating the measured velocity data over the cross-sectional area of the river, ADCP flow meter is able to calculate the flow rate of the Balonne River during floods. This serves to help identify the amount of water passing through a certain section of the river, which is highly important for flood forecasting and managing the overall water resources.

Application in research on sediment transport: Sediment movements are closely associated with the flooding of the river. Suspended sediment in the water can be detected by using ADCP meter through analyzing the backscattered acoustic signals; the method allows studies into the amount of sediment transported by flooding, which has implications for understanding long-term riverbed changes and their impact on the ecological environment of the river.

5. How can the data measured by ADCP be utilized for flood warning and risk management of the Balonne River?

Flood warning:

Velocity and flow data monitoring: The ADCP continuously monitors the velocity of water and its flow rate, enabling authorities to identify abnormal increases in the respective parameters. For instance, a sudden surge in the flow rate could indicate that a flood is imminent or gaining in intensity. Thresholds based on historical data and real-time monitoring enable early warnings to communities along the Balonne River.

Water Level Prediction and Warning: The velocity data obtained by ADCP profiler can also be used in conjunction with other hydrological models to predict changes in water level. Because the water velocity is affecting how quickly the water accumulates or drains in the river channel, accurate velocity measurements can help improve the accuracy of water level forecasts for timely warnings to residents in areas prone to floods.

Risk Management

Water Conservancy Project Scheduling Decision Support : Flow and velocity data from ADCP measurements allow for decisions to be made in the operation of water conservancy projects like dams and weirs along the Balonne River. For instance, the release of water from a dam might need modification based on the measured rate of flow during a flood to mitigate downstream flooding and at the same time ensure the safety of the dam structure.

Assessment of Flood Disaster and Emergency Response: In the event of a flood, ADCP data will be useful in ascertaining the extent of damage caused by the flood, for instance, areas of severe erosion or inundation. This information is useful for formulating the emergency response plans and also for future floods mitigation and recovery efforts.

6. What is required to have high-quality measurement of the currents of the Balonne River?

The high-quality measurement of the currents in the Balonne River requires a few aspects of the equipment. This starts with the material reliability of the ADCP. It must be such that it can stand up to the harsh aquatic environment of the river and not be easily tampered with by water, sediment, and variable water chemistry.

Secondly, a smaller size, lighter weight, and lower power consumption are desirable characteristics. A smaller and lighter ADCP is easier to deploy and retrieve, especially in areas that may be difficult to access along the river.

Low power consumption allows for longer operation times without the need for frequent battery replacements or power source connections, which is beneficial for continuous monitoring. Besides, lower cost allows for wider application of the equipment to perform large-scale measurements at different parts of the Balonne River.

The casing of the ADCP is preferably made of titanium alloy. Some key advantages with the use of titanium alloy include excellent corrosion resistance in the generally corrosive water of the river, high strength, and toughness for the mechanical stresses caused by water in flux and possible impacts from debris. Besides that fact, it also features relatively low mass density, adding to the lightweight nature of the device.

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

In order to choose the right ADCP equipment for current measurement in the Balonne River, several factors should be taken into consideration. Based on the usage purpose, during the horizontal section measurement, the Horizontal Acoustic Doppler Current Profiler (HADCP) is an appropriate choice. It is designed to measure the water velocity across a horizontal plane, providing valuable information about the flow patterns in a specific reach of the river.

For vertical section measurement, the vertical ADCP is more appropriate because it can accurately record the velocity profile from the riverbed to the water surface along a vertical line perpendicular to the flow direction. Second, different frequencies of ADCP are suitable for different water depths. For instance, a frequency of 600 kHz for ADCP is normally suitable for water depths within 70 meters. It can be used to make relatively detailed and accurate measurements in shallower parts of the Balonne River.

Whereas an ADCP with a frequency of 300 kHz is more appropriate for deeper waters up to approximately 110 meters, which can be useful in areas where the river has a greater depth. There are quite a few famous brands of ADCP in the market, like Teledyne RDI, Nortek, and Sontek. The best selection in economical quality could be the China Sonar PandaADCP. Material: All-titanium alloy. Not only can it make sure that the instrument will be durable, reliable, and resistant in the river environment, but also provide an amazing price-performance ratio. You can know more about it on their official website: https://china-sonar.com/.

The Finlay River originates in British Columbia, Canada. It forms one of the major tributaries of the Peace River. The river rises in the Rocky Mountains.

It flows across the landscape, covering portions of forest, mountain valleys, and some meadowlands. It supports local ecosystems for fish and other aquatic life, as well as providing some limited agriculture and household water sources in local communities.

It has a continental climate in terms of climate and water sources. Through spring and summer, there is snowmelt from mountains that feeds the river, apart from rainfalls. Such water inputs bring changes in the river's water level. Flooding can occur in areas with heavy snow melting or during instances of heavy rainfall and may be more pronounced in generally lower-lying areas and in known flood-prone areas along its course.

2. What are the reasons for floods in the Finlay River?

Snowmelt and Heavy Rainfall: Flooding in the Finlay River is mainly caused by rapid spring snowmelt and heavy rainfall throughout the wet season. The enormous volume of water contributed by snow melting in the Rocky Mountains and catchment area, in addition to rainwater, raises the river's volume in a very short period. The mountainous terrain around its source hastens the runoff process, channeling a large volume of water downstream.

Topography: Floodplains and low-lying areas along the river's course allow water to spread out and collect. The gentle slopes reduce the speed of the water, making it even easier to flood. The confluence of tributaries adds extra water when at high flow, making a flood condition worse.

Soil and Vegetation Changes: Changes in soil and vegetation cover due to human activities or natural causes can lead to the modification of flood patterns. Deforestation in the catchment area reduces the absorbing and water-retaining capacity of the land. This leads to increased surface runoff and a more rapid influx of water into the river, increasing the flood risk.

The Acoustic Doppler Current Profiler (ADCP) is an indispensable tool in the understanding and managing of the Finlay River flow during floods.

3. How do ADCPs using the principle of the Doppler work?

The ADCPs work on the principle of the Doppler effect. The instrument sends out an acoustic signal into the water. Due to the flow of water, the signal is scattered by the moving water particles. When the acoustic signal is reflected back to the ADCP current profiler, because of the Doppler effect, the frequency of the reflected signal is changed.

The ADCP measures the differential frequency of the signal emitted and the signal received. From this frequency shift, it can determine the velocity of the water at various depths. These devices normally have multiple transducers that are capable of emitting and receiving acoustic signals in various directions. In this respect, it is able to build up a profile of the water velocity across a section of the river.

For instance, when the water is moving towards the acoustic doppler velocity meter, the frequency of the reflected signal is higher than that of the emitted one. In contrast, if the water moves away from the ADCP, it detects a signal with a lower frequency. Since these changes in frequency are measured very accurately with the ADCP and mathematical algorithms for treatment applied correspondingly, one can obtain the velocity at different points within the measurement range.

4. What are the applications of ADCP in floods of the Finlay River?

4.1 Velocity Measurement

During flood events in the Finlay River, ADCP flow meter is important for measuring the actual velocity of the water flow. It continuously monitors the water velocity at different depths and locations and hence provides real - time data about the speed at which the water is moving. This will be crucial to understand the dynamics of the flood: to understand the direction in which the floodwater is going to move and the intensity with which it will travel.

4.2 Flow Measurement Application

ADCP profiler can also measure the flow rate of the Finlay River. By combining the measured water velocities at different points across a section of the river with the known cross - sectional area of the river, it can calculate the total volume of water flowing through the section per unit time - that is, its flow rate. This information is of paramount importance to determine the general volume of water during a flood and, therefore, is useful for decisions on flood control and water resource management.

4.3 Application in Sediment Transport Research

Besides flow and velocity measurement, ADCP is helpful in sediment transport studies along the Finlay River during flooding. Whenever the water flows, it carries sediments. The ADCP is effective in detecting changes in the backscattered acoustic signal that may originate from the presence of sediments. It is possible to estimate, from such changes, the quantity and movement of sediments. This information is relevant for the characterization of the long-term evolution of the riverbed and for assessing the consequences of floods on the sedimentary environment of the river.

5. How does the data measured by ADCP be applicable to flood warning and risk management of the Finlay River?

5.1 Flood Warning

Velocity and Flow Data Monitoring: In this regard, real-time velocity and flow data obtained from ADCPs are continuously monitored. When the velocity of the water measured is higher than a certain level, or the flow rate is increasing obviously, it may indicate that a flood peak is arriving or a flooding situation may occur. This allows necessary early warnings to relevant authorities on the evacuations of people in low-lying areas or reinforcing flood defenses.

Water Level Prediction and Warning: Measured flow data correlated with historical water level data using appropriate hydrological models can be used to predict future water levels from ADCP data. In case the predicted water level is going to exceed the flood warning level, timely warnings can be issued to the public, enabling them to prepare for the flood.

5.2 Risk Management

Support for Water Conservancy Project Scheduling Decisions: The accurate flow and velocity data from ADCP can help the decision-maker on the operational aspect of water conservancy projects such as dams and sluices. For example, based on the measured water flow, the release of water from a dam can be regulated to control the water level in Finlay River and mitigate the impact of floods.

Assessment of Flood Disaster and Emergency Response: The ADCP data after the flood event contribute to assessing the intensity of the flood. It includes information like the area of inundation, velocity of floodwater, and sediment deposition during this process. This type of information is important for formulating emergency response plans, as well as for carrying out post-flood reconstruction and rehabilitation work.

6. What’s needed for high - quality measurement of the Finlay River currents?

For high - quality measurement of the Finlay River currents, several factors need to be considered. Firstly, the equipment used should have reliable materials. The casing of the ADCP is of particular importance. It is recommended that the casing be made of titanium alloy. The strength of the Titanium alloy is very high, thus allowing the equipment to resist the pressure and impact resulting from the water flow in the river. The material is also highly resistant to corrosion; this is very important given that the water environment at Finlay River may contain different corrosive substances.

Besides material reliability, the size and weight of the equipment should be as small and light as possible. This makes installation and operation of the ADCP in various locations along the river easier, particularly in the most inaccessible areas. Low power consumption is also very important, as this enables longer continuous operations without frequent replacement of batteries or connection to a power source. Besides, the cost of the equipment should not be so high to enable large-scale measurement. A lesser cost enables more ADCPs to be deployed along Finlay River, hence offering an increased solution of comprehensive and detailed data for flood management.

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

The following are some of the aspects that should be considered in choosing the right equipment for current measurement in Finlay River: first, if it is to be used in horizontal cross-section measurement, an HADCP must be chosen; otherwise, in the case of vertical cross-section measurement, a Vertical ADCP would be proper to be used.

Secondly, different frequencies apply to different water depths. For instance, a 600 kHz ADCP would be suitable for water depths within 70 m. If the water depth in Finlay River is within this range and meets the requirements of measurement, then a 600 kHz ADCP may be considered. If the water is much deeper, say over 70 m and up to 110 m, a 300 kHz would be much more appropriate, since it can provide more accurate measurements in such depths.

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