ADCP in the Canadian River Flood Management

1. Where is the Canadian River?

The Canadian River ranks as one of the major rivers in the United States while its watershed partly stretches into Canada. Its headwaters are located in the high plains of Colorado and New Mexico.

Geographically, the river runs through Texas, Oklahoma, and Arkansas and assumes great importance in the arid and semi-arid lands it flows through. Among the cities and towns it goes by are Amarillo and Oklahoma City. Its course gets intercepted by all types of topography from plains to canyons to floodplains.

Precipitation in the Canadian River area ranges from semi-arid to a continental climate. This precipitation is highly variable and can be quite scant in some areas. Snowmelt from the mountains in its upper reaches and runoff from a big watershed supplement its water supply. Heavy rainfall events, usually less frequent but more intense, contribute much more to the river's flow and create flooding.

2. What causes flooding in the Canadian River?

Contributory factors to flooding in the Canadian River are diverse; rainfall events intense and very localized at times trigger the sudden surge of water. In a semi-arid climatic region, most of the time the soil would be incapable of absorbing more water, so in places where heavy rain falls, much of it runs off quickly into entering the river, and the water level surges up very fast.

Second, the snowmelt in the upper reaches may cause flooding of the river. If there is a warm spell that causes ultimate melting of the snow quickly, a large volume of water may add to the river system. This sudden increase in the volume of water may be more than the river's capacity and thus might cause over - bank flooding.

Topography of the river basin is another factor. Since this area has floodplains and relatively flat sections of land along the river, there is a high possibility that water could spread out and acquire during high-flow periods. Moreover, human activities-development and urbanization-will go on, increasing impervious surfaces and enhancing surface runoff. Agricultural activities including over-irrigation and soil tillage result in the erosion of soil that eventually gets deposited in the river channel, reducing its carrying capacity. This, too, often results in flooding incidents.

Presently, Acoustic Doppler Current Profiler (ADCP) is a more advanced and convenient measure in the management of flow conditions in the river in the event of flooding.

3. How are ADCPs using the principle of Doppler working?

Working principle of ADCP current meter is based on the Doppler effect. The device sends an acoustic signal into the water. Since the water is in flow, the signal starts its interaction with the moving water particles. The frequency of the reflected signal as received by the ADCP current profiler has been shifted due to the Doppler effect.

It calculates the shift in frequency between a transmitted signal and the received signal. From this, it will be able to pre-analyze the water speed at other levels in such a way that a frequency shift analysis is done. Most ADCP flow meter have multiple transducers with the capability of transmitting and receiving acoustic signals in multiple directions. This, in turn, allows them to obtain a profile of the water velocity across a section of the river.

For example, the frequency of the reflected signal would be higher than that emitted if the water is moving towards the ADCP meter, but vice-versa if it is moving away from it. This frequency shift is what the instrument is able to measure with high accuracy, and using proper mathematical algorithms, the ADCP will be able to correctly map the exact velocity of the water at every point within its measurement range.

4. What is the application of ADCP in floods of the Canadian River?

4.1 Measurement of Velocity

The ADCP profiler forms an important basis in the measurements of velocity in water flow upon flooding of the Canadian River. Offering real-time information on the rate at which the water is traveling by constantly watching its speed over different depths and distances from the apparatus. This becomes useful in understanding the dynamics within the flood for example, determination of direction and intensity of movement of the floodwaters.

4.2 Flow Measurement Application

It can also measure the flow rate of the Canadian 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, or the flow rate. It will be vital in understanding the general volume of water in case of a flood and hence in decision-making about flood control and water resource management.

4.3 Sediment Transport Study Application

Other than the flow and velocity measurements, ADCP finds application in the study of sediment transport in the Canadian River at times of floods. While the water flows, it carries sediments. The acoustic doppler flow meter can detect changes in the backscattered acoustic signal caused by the presence of sediments. By analyzing these changes, it is possible to estimate the amount and movement of sediments, an important component in understanding the long-term evolution of the riverbed and flood effects on the river's sedimentary environment.

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

5.1 Flood Warning

Velocity and Flow Data Monitoring: The actual velocity and flow data are derived continuously from ADCP. If the water velocity is found to be higher than the threshold value or if there is a greater inflow rate, then it may indicate an arriving flood peak or a situation of flooding. The advance warning in this respect enables the concerned authorities to adopt necessary precautionary measures with respect to moving people out of low-lying areas or strengthening flood defenses, among other measures.

Water Level Prediction and Warning: Measured flow data correlated with historical water level data can have their future water levels estimated using appropriate hydrological models, hence the ADCP data. In case the estimated water level is going to rise above the flood warning level, timely warnings can be issued to the public for preparation against the flood.

5.2 Risk Management

Water Conservancy Project Scheduling Decisions: Flow and velocity data provided by ADCP would be useful in operating decisions for water conservancy projects like dams and sluices. In this regard, depending on the water flow measured, the release from a dam could be regulated so as to control the level of water in the Canadian River and, hence, mitigate the impact of floods.

Evaluation of Flood Disaster and Emergency Response: After a flood occurrence, the information acquired by ADCP will be helpful in appraising the severity of the flood in terms of the area to which the flood was confined, the velocity of the floodwaters, and the amount of sediment carried and deposited. All this information shall form the basis of devising the plans for emergency response besides finding value in carrying out post-flood reconstruction and rehabilitation works.

6. What is required for the measurement of the Canadian River currents to be of high quality?

High-quality measurement of the Canadian River currents requires a number of considerations. First, the materials used in the equipment should be reliable. It is the case covering the acoustic doppler velocity meter. The casing should be made from the titanium alloy. Titanium alloy has a number of advantages. It has high strength that can bear the pressure and impact of water flowing in the river. Besides, it is highly corrosion-resistant; this again is a very vital property considering the water environment of the Canadian River, which could have many corrosive substances.

Besides material reliability, the size and weight of the equipment must be small and light. That makes it quite easy to install and operate ADCP in various river points, especially in those with difficult access. Low power consumption is one more important aspect since it gives longer operation continuously without changing batteries or hooking it to a power source. Besides, the equipment cost should also be relatively low in order to enable large-scale measurement. Because it is cheaper, more ADCPs could be installed along the Canadian River to give more detailed data relevant to flood management.

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

The selection of proper equipment for the current measurement in the Canadian River has to be done considering many aspects. Firstly, concerning the type of measurement to be done, an HADCP is to be selected if it is horizontal cross-section measurement; on the other hand, a Vertical ADCP will be appropriate if the purpose is vertical cross-section measurement.

Second, different frequencies are suitable for different water depth. For instance, a 600 kHz ADCP is suitable for a water depth within 70 m. If the depth in the Canadian River falls within this range and the measurement requirements match, a 600 kHz ADCP can be considered. Still, for waters where the depth is over 70 m up to 110 m, the 300 kHz ADCP is more suitable because that can yield an accurate measurement in such water depth.

Some well-known brands of ADCPs in the market are Teledyne RDI, Nortek, and Sontek. For those people who are budget-conscious, China Sonar PandaADCP will be an excellent alternative. 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.