ADCP in the Athabasca River Flood Management

1. Where is the Athabasca River?

The Athabasca River is one of the major rivers across Alberta, Canada. It originated from the Columbia Icefield in the Rocky Mountains.

Starting from its geographically diversified landscape-from mountainous areas at its source, giving way to vast expanses of boreal forests and plains further downstream toward the north-it flows through key cities such as Fort McMurray. Besides being an important waterway for transportation, it supplies a helping amount of water not only for industrial needs of various kinds but also for oil sands operations and ecosystem needs locally.

This region wherein the Athabasca River is located falls under a subarctic climate in terms of rainfall. The precipitation here is principally all-year round, though with a very large proportion falling as snow during winter. During the spring and early summer seasons, the melting of snow substantially contributes to the water of the river. The general rainfall amount during the summer months contributes a lot to the flow of the river. It is prey to fluctuation in the water level because of a combination of snowmelt and rainfall, and in years with heavy precipitation or rapid snowmelt, there is a possibility of floods.

2. What are the causes of floods in the Athabasca River?

There are many contributory elements that cause flooding in the Athabasca River. The primary factor is the melting of the snow in the spring, which tends to happen very rapidly. Due to sudden rises in temperature, the heavy amount of snow collected in the mountains and other places during winter months melts at a tremendous rate. This sudden volume of water may be more than the river can handle, hence the water level starts to rise and creates flooding.

The second factor contributing to flooding is high summer rainfall. Intense and continuous rain showers cause the level of water in the river to surge high. The possible incapacity of the land in the area, particularly in the upper reaches of the river, to absorb the great volumes of water may be due to the nature of the soil and, in some parts, a permafrost condition. This results in most of the rainwater running into the river.

Topography also plays a vital role on the river basin. Flat areas and floodplains along the river basin create room for water to spread out and amass. Human activities such as developing the oil sands are another factor. Construction and expansion within this area disrupts the natural drainage of the area. Also, activities that concern the extraction of resources lead to soil erosion and sedimentation in the river, reducing its carrying capacity and increasing the possibility of flooding.

Acoustic Doppler Current Profiler (ADCP) has become a more sophisticated and convenient measurement technique for much-needed better understanding and management of flow conditions of the river during flood events.

3. How Do Doppler Principle ADCPs Work?

The principle of working for ADCP profiler is Doppler. When an ADCP metersends an acoustic signal into the water, the signal bounces off the moving particles of the water. Since in case of a flow, the frequency of the reflected acoustic signal will fall different after it reaches the ADCP due to Doppler's effect.

The ADCP measures the frequency difference between the emitted signal and the received signal of the acoustic. It estimates by analyzing the frequency shift the velocity of the water at various velocities. Commonly, several transducers that may send and receive acoustic signals in different directions are fitted on the device, which thus can obtain a profile across a section of the river.

For example, if the water is moving towards the ADCP flow meter, then the frequency of the reflected signal would be higher than the emitted one; vice versa if the water is moving away. The accurate measurement of such frequency changes, with appropriate mathematical algorithms applied, therefore allows the ADCP current profiler to correctly calculate the velocity of the water at different points within its measurement range.

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

4.1 Velocity Measurement

The application of ADCP current meter in the measurement of the velocity of water flow during flood events along the Athabasca River is very important. The continuous measurement of water velocity at different locations and depths gives real - time information on the speed at which water is moving. This information shall be very useful in the dynamics of understanding the flood in terms of predicting the direction and intensity of the movement of the floodwaters.

4.2 Flow Measurement Application

The acoustic doppler velocity meter can also perform flow rate measurement on the Athabasca River. Its mechanism includes computation of the total volume of water flowing through a section in a unit time, namely, the flow rate, by combining the measured water velocities across a section of the river at many points and the already known cross-sectional area of the river. This information is very vital to determine in general the quantity of water during a flood and, therefore, acts as a basis for decision making on flood control and water resources management.

4.3 Application in Sediment Transport Research

Apart from flow and velocity measurement, ADCP is useful in the sediment transport research along the Athabasca River during floods. Carried within the flowing water are lots of sediments, and the acoustic doppler flow meter detects changes due to sediment presence in the backscattered acoustic signal. The researchers would have been able to make estimations of the quantity and movements by analyzing these changes. Such knowledge is important for long-term understanding in the evolution of the riverbed and the impact that floods have on the sedimentary environment of this river.

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

5.1 Flood Warning

Velocity and Flow Data Monitoring: ADCP continuously monitors the real-time velocity and flow data. If the velocity of the water as measured goes above a threshold value or if the flow rate is too high, such conditions may be indicative of the approach of a flood peak or that there is a possibility of flooding. The possibility of issuing early warnings through such advance indications may allow relevant authorities to take appropriate precautionary measures by evacuating people from low-lying areas or strengthening flood defenses.

Water Level Prediction and Warning: Measured flow data correlated with historical water level data using appropriate hydrological models can facilitate the prediction of future water levels from ADCP data. If the predicted water level is to exceed the flood warning level, timely warnings can be issued to the public to prepare for the flood.

5.2 Risk Management

Support decisions in operating water conservancy projects: the accurate flow and velocity data from ADCP supports decisions in operating water conservancy projects, like operating a dam or sluices. For example, regulating the quantity of released water from a dam by the water flow measured controls the water level in the Athabasca River and reduces the impact caused by floods. Flood Disaster Assessment and Emergency Response: Data collected by the ADCP on flooding can be used to assess the severity of the flood in terms of the area covered, the speed of floodwaters, and the sediment load carried. This is indeed essential information that has to go into the formulation of emergency response plans, and indeed even in the implementation of post-flood reconstruction and rehabilitation work.

6.What is necessary to make high-quality measurements of the currents of the Athabasca River?

High-quality measurement of the current of the Athabasca River requires many aspects. The equipment used for measurement should have reliable materials. In this regard, the casing of the ADCP is most important. It is recommended that the casing must be manufactured from the Titanium alloy. The Titanium alloy has many advantages. It is of high strength, enabling the equipment to bear the pressure and impact of the flowing water in the river. It is also highly resistant to corrosion, something that would be important considering the water environment of the Athabasca River, which may contain many corrosive substances.

Apart from the reliability of the material on the equipment, the size and weight of the equipment should also be small and light. This makes the installation and operation of the ADCP in places along the river, especially those that are not accessible, easier. It should also have low power consumption for longer continuous running with fewer battery replacements or hookups to a power source. The cost of the equipment should also be relatively low to be able to make large-scale measurement. Cost is lesser, which would enable more ADCPs being deployed along the banks of Athabasca River providing more comprehensive and detailed data for flood management.

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

Considering proper equipment for the current measurement in the Athabasca River, a number of aspects are taken into consideration. For instance, depending on the type of measurement, the kind of instrument required for horizontal cross - section measurement is Horizontal ADCP (HADCP). While in case of measurement of vertical cross - section, a Vertical ADCP is applicable.

Then, different frequencies are suitable for different water depth. Such as the 600 kHz ADCP suits for water depth within 70 m. If the water depth of the Athabasca River is in this range and fits the measurement requirements, the 600 kHz ADCP can be considered. More appropriately, it would be a 300 kHz ADCP that can work in waters over 70 m up to 110 m for more detailed flow velocity measurements.

Presently, there are several well-known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those who seek a cost-effective option, the China Sonar PandaADCP is perhaps one of the good options available. 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 find more information about it on its official website: (https://china-sonar.com/).

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