ADCP's application in flood management of Finlay River

1. Where is the Finlay River?

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.

There are several well - known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost - effective option, the China Sonar PandaADCP is a great choice. It is made of all - titanium alloy material, which ensures its durability and reliability in the water environment. Moreover, it offers an incredible cost - performance ratio. You can go to its official website for more details: (https://china-sonar.com/).

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