How to Measure Water Current of Peace River?

1. Where is Peace River?

Peace River is a major river in the west of Canada. Its origin is in the Rocky Mountains of British Columbia. From there, it passes through Alberta and the Northwest Territories. The river passes through many different types of landscapes, from the mountainous regions at its source to the large plains and forests downstream.

This river is a vital part of the local ecosystem. It provides a habitat for numerous fish species like trout and sturgeon, as well as a host of other wildlife including beavers, deer, and various bird species. Along its banks, there are small towns and rural communities that rely on the Peace River for water supply, irrigation for agriculture, and as a means of transportation in some areas.

The Peace River has also played a very important cultural role in the history and traditions of the Indigenous peoples of the region, featuring in their stories, hunting grounds, and trading routes for many hundreds of years. As well, it has witnessed the growth and development of the settler communities over time, becoming an integral part of the shared heritage of the area.

2. What is the nature of flow in the Peace river?

The flow rate in the Peace River is seasonal. During spring, the snowmelt from the Rocky Mountains increases the flow of the river considerably. During this time, the level of the water rises and the current becomes pretty strong; it carries sediments and nutrients that are helpful to the downstream ecosystems.

During the summer, the flow rate stabilizes somewhat. Nonetheless, it remains to have provided a regular amount of its supply, to the needs of the area communities and the environment altogether. During this period of dry conditions, the river also feeds from the rainfall in its catchment area. By autumn and winter, this flow rate decreases. The average flow rate depends on factors such as the amount of snowfall in the upstream regions, the topography of the river basin that dictates how water is collected and drained, and the pattern of water usage by the local communities, including agriculture and domestic consumption.

3. How to measure water current of Peace River?

This conventional technique relies on the use of mechanical or electronic velocity meters. These meters are placed in the water at strategic points and measure the speed of water that rushes past them. However, for an integrated understanding of the current, multiple placements at different locations and depths are required. It is quite a time-consuming process and may not always yield a continuous profile of the current throughout the water column.

Acoustic Doppler Current Profiler (ADCP) Method

The ADCP current meter is a more advanced and efficient method of measuring water current, using sound waves to measure the velocity of water simultaneously at different depths. By emitting acoustic signals and analyzing the Doppler shift of the reflected signals, it can create a detailed profile of the current from the surface to the riverbed. This provides a much more accurate and comprehensive measurement of the water current across different sections of the river.

Buoy Method

The principle involves setting buoys in the river and tracking their movement over some time. Displacement of these buoys through the water current gives the speed and direction of flow. There are limitations to this method since it does not always provide accurate velocity at various depths, apart from being subject to external influences such as wind and wave actions, which may distort the buoy's movement.

Among these methods, the ADCP flow meter method is more advanced and convenient for measuring the water current of the Peace River.

4. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of the Doppler effect. When an acoustic signal is transmitted from the ADCP profiler transducer into the water, the sound waves scatter in all directions and interact with the moving water particles. Since the water is in a flow, the frequency of the reflected sound waves back to the transducer shifts, so-called Doppler shift.

If the water is moving towards the transducer, the frequency of the reflected waves will be higher than the emitted frequency. In the case where the water is moving away from the transducer, the frequency will be lower. Precise measurement of this frequency shift at multiple angles and depths allows the ADCP meter to calculate the velocity of the water in various directions and at different levels within the water column. This enables it to create a detailed profile of the water current, providing valuable information about the speed and direction of the flow from the surface to the riverbed.

5. What's needed for high-quality measurement of Peace river currents?

The measuring equipment should have several characteristics to make the measurement of Peace River currents of high quality. Construction materials used should be solid for reliable, consistent, and correct measurement. Small dimensions are advantageous because the release and raising of the equipment become much easier in the river and places that are badly accessible. It should have a small weight to keep the installation work easy to manage with less effort.

Low power consumption is necessary to allow the equipment to operate for long periods without frequent battery replacements or a complicated power supply setup. Cost-effectiveness is another important factor because it allows for wider usage and larger measurement campaigns.

For the casing of the ADCP profiler, titanium alloy is an excellent choice. Titanium alloy has many advantages. High corrosion resistance will be critical since the casing continuously has exposure to water that will very likely contain a mixture of different minerals, sediments, and pollutants. A high strength-to-weight ratio should give a strong yet light casing. The material used is resistant to mechanical stresses during deployment and while operating in the moving water in the Peace River.

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

When choosing the right equipment for measuring the current of the Peace River, two main factors should be considered.

Depending on the usage purpose, for horizontal cross-section measurement, the Horizontal ADCP (HADCP) is the suitable option. It is designed to accurately measure the flow velocities across a horizontal plane in the river, which is useful for understanding the lateral distribution of the current. For vertical cross-section measurement, the Vertical ADCP is more appropriate as it focuses on profiling the current from the surface to the bottom along a vertical line in the water column.

Different frequencies of ADCPs are fitted for different water depths. For instance, the ADCP current profiler frequency of 600 kHz is fitted for water within 70 m. This could provide current measurements that are quite accurate in the relatively shallower parts of the Peace River. Similarly, an ADCP with a frequency of 300 kHz will be more fitted for deeper waters up to 110 m, which can be useful in areas where the river has greater depth.

There are famous brands of ADCPs, including Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective option with good quality, the China Sonar PandaADCP is highly recommended. It is made of all-titanium alloy material and offers an incredible price-performance ratio. You can find out more about it on its website: https://china-sonar.com/.

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