ADCP in the North Saskatchewan River Flood Management

1. Where is the North Saskatchewan River?

The North Saskatchewan River is one of the major rivers of Western Canada. It originates in the Canadian Rockies of Alberta.

Geographically, it passes through Alberta and Saskatchewan, flowing through Edmonton to Saskatoon. Topographically, the course of this river constitutes several types of landscapes. It passes through mountainous and forested regions in its upper reaches, while further eastward it passes through plains and agricultural areas. The North Saskatchewan River serves as an important source of water for many uses: municipal water supplies, agriculture, and power generation.

Speaking climatically, the river flows through the area of the continental climate. Precipitation in this area can be expected throughout the whole year but is higher during summer due to thunderstorms. In addition, the volume of water in this river is significantly fed by snowmelt in spring from the mountains. The combination of rainfall and snowmelt can sometimes bring extreme changes in the water level of the river; therefore, in cases of heavy rainfall or rapid snowmelt, the flood risks are higher.

2. Why flooding occurs in the North Saskatchewan River?

Flooding in the North Saskatchewan River has been caused for numerous reasons. One of the prime causes of flooding is when heavy rainstorms fall during the summer. In this season, water rapidly rises because thunderstorms often unleash heavy storms that fall in a limited duration of time and the river is not capable enough of dissolving that amount of water.

The second factor is the snowmelt factor in the spring. When there is a sudden rise in temperature and hence snow is melting fast, a huge volume of water enters the river within a very short time. Sometimes the river is unable to handle this sudden inflow of water, and therefore flooding may occur.

Another cause is topography. Indeed, along the river, land stretches are rather flat, and hence water may easily accumulate in such spots. Most importantly, human actions were involved in the process: growth of cities with expansion of infrastructure-almost impervious surfaces in urban areas-increased the surface run-off. Events like irrigation and land clearing in agriculture are some of the events that contribute to disturbance and stability of the soils, with increased erosion leading to deposits of sediment in the river, reducing its ability to carry more material due to reduced carrying capacity, hence flood-prone.

ADCP- Acoustic Doppler Current Profiler offers an advanced and convenient means of measurement and management of the flow conditions within the river in case of flooding.

3. How do ADCPs using the Doppler principle work?

The working of an Acoustic Doppler Current Profiler(ADCP) is based on the Doppler principle. A signal is emitted into the water acoustically. When this happens in flowing water, the signal interacts with moving water particles. When the acoustic signal reflects back to the ADCP, a shift in frequency of the reflected signal occurs due to the Doppler effect.

The acoustic doppler flow meter detects the difference in frequency between the emitted and the received signal. From this frequency shift, it can deduce the velocity of the water at various depths. Usually, an ADCP has several transducers, which could emit and receive acoustic signals in various directions. This enables them to obtain a profile of the water velocity over a section of the river.

For example, the reflected signal would have a higher frequency than that emitted if water flows towards the ADCP current profiler. On the other hand, it would have a lower frequency if water is flowing away from the ADCP flow meter. Exactly by measuring such frequency changes and with the use of appropriate mathematical algorithms, the ADCP current meter is able to determine the velocity of the water at various points within its measurement range with quite good accuracy.

4. What are the uses of ADCP in the North Saskatchewan River floods?

Velocity Measurement

The ADCP meter has played a significant role in the accurate measurement of the flow velocities during flood events in the North Saskatchewan River. It continuously monitors the water flow velocity with respect to depth and location; hence, it provides real-time data regarding the speed at which the water is moving. This proves to be an added valuable input regarding the dynamics of the flood, which in turn would be helpful in predicting the direction and intensity of the movement of floodwaters.

Flow Measurement Application

Another possible application for which ADCP can serve is the flow rate measurement on the North Saskatchewan River. By integrating the measured water velocities at different points across a section of the river and the known cross-sectional area of the river, it is able to calculate the total volume of water flowing through the section per unit time-the flow rate. It also forms the very essential data in quantifying the total quantity of water in a flood and decision-making process in flood control and management of water resources.

Application in Sediment Transport Research

Other than flow and velocity measurement, ADCP profiler is helpful in sediment transport studies along the North Saskatchewan River during floods. While the water is in flow, it carries sediments. This is possible because the ADCP is able to detect changes in the backscattered acoustic signal due to the presence of sediments. Researchers might then be able to estimate the amount and movement of the sediments from such variations, useful in understanding long-term evolution of the riverbed and the impact of floods on the river's sedimentary environment.

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

Flood Warning

Monitoring of Velocity and Flow Data: In real-time, the acoustic doppler velocity meter obtains velocity and flow data continuously. If the measured water velocity is larger than the threshold value or if there is a sudden rise in the flow rate, it may indicate the arrival of the flood peak or it is a potentially flooding situation. It allows the necessary warning in advance to relevant authorities for taking preliminary measures to evacuate people from low-lying areas or strengthening flood defenses.

Water Level Prediction and Warning: Measured flow data correlated with historical data of water level and appropriate hydrological models can serve to predict future water levels using ADCP data. If the forecasted water level is to surpass the flood warning level, timely warnings can be issued to the public for their preparation against flood.

Risk Management

Water Conservancy Project Scheduling Decision Support - With the precision of flow and velocity data, the scheduling decision can be supported in water conservancy projects such as the operation of dams and sluices with ADCPs. The release from the dam can be controlled based on the water level control in the North Saskatchewan River against floods by the measured release of water. Assessment of Flood Disaster and Emergency Response: Data from ADCP will help in assessing the magnitude of flood concerning its inundation extent, velocity, and quantity of sediment deposition afterward. It forms one of the cardinal bases for drafting emergency response plans and for conducting post-flood reconstruction and rehabilitation works.

6. What do I need to measure the currents of North Saskatchewan River with high quality?

The process of high-quality measurement involves several factors that are taken into consideration, one of which is the material of the equipment that will be in use. Much emphasis is taken on the casing of the ADCP. It is recommended to have the casing made from a titanium alloy. The titanium alloy has a couple of advantages:. It has high strength that enables the equipment to bear the pressure and impact of the flowing water in the river. It is highly resistant to corrosion, which is very important considering the water environment of North Saskatchewan River that may have various corrosive substances in it.

Besides the reliability of the material, the size and the weight of the equipment should be small and light. That will make the deployment and operation of the ADCP more straightforward at various locations in the river, including those that are not accessible. Another important point is low power consumption, which enables longer continuous operations without replacing the battery or connecting it to a power source frequently. Besides, the cost of the equipment should be relatively low to enable large-scale measurement. Lower cost will enable the deployment of more ADCPs along the North Saskatchewan River to provide more detailed and frequent data related to flood management.

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

Selection of proper equipment for the measurement of the current in the North Saskatchewan River will involve a number of factors. If the type of measurement required is horizontal cross-section measurement, then an HADCP - Horizontal ADCP - should be selected. In case the requirement is for vertical cross-section measurement, the Vertical ADCP is the right one.

Different frequencies may suit different water depth. For example, the 600 kHz could be fit for the water depth within 70 m. If the water depth in North Saskatchewan River is within the range, and the measurement requirement fits, then a 600 kHz is considered. The ADCP 300 kHz shall be fit for deeper waters, such as those exceeding 70 m up to 110 m, for better results in the measurements at such depths.

There are quite a few popular brands of ADCPs out in the market. These include Teledyne RDI, Nortek, and Sontek. But for those on a budget, one of the impressive ones would be China Sonar PandaADCP. 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.