How to measure water current of North (Great Lakes) River?

1. Where is North (Great Lakes) River?

The North (Great Lakes) River is a part of a splendid and very vast water system in North America. It meanders through an area full of natural beauty as well as vibrant human culture.

It is closely associated with the Great Lakes, a series of several interrelated freshwater lakes, Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. These are surrounded by various states along its coasts, like Michigan, Wisconsin, Minnesota, Illinois, Indiana, Ohio, Pennsylvania, and New York of the United States, besides Ontario and Quebec of Canada being also connected with this mighty river system.

Numerous very attractive cities and towns dot the area along the North River, from urban jungles such as Chicago at Lake Michigan with its great skyward bound buildings and bustling cultural activities down to the quiet, historical town of Niagara-on-the-Lake at Lake Ontario famous for its vineyards and very well-maintained older architecture. The river and its surroundings host a very diverse population, with major industries like shipping, fishing, manufacturing, and tourism. The natural sceneries vary from sandy beaches along the lake shores to lush forests and rolling hills farther inland, making it a haven for wildlife and a paradise for outdoor enthusiasts who also enjoy boating, hiking, and birdwatching.

2. What is the North (Great Lakes) river like in terms of flow rate?

The North (Great Lakes) River is very significant. It is an important transportation channel in the region, shipping products ranging from raw materials such as iron ore and grain to manufactured goods. It is also a vital part of supporting a rich and diverse aquatic ecosystem. These lakes and the river are home to many species of fish, from the prized Lake Trout to the abundant Smallmouth Bass, as well as numerous other forms of aquatic life.

In terms of flow rate and discharge, it is different according to the various sections and seasons. Generally, the flow is related to precipitation, snowmelt in surrounding areas, and regulation by dams and other water management structures. During spring, it often has higher flow rates when the snow melts from surrounding mountains and higher elevations. This flow will be minimum in the summer or dry parts of the year when rain is below average. Overall, its flow characteristics are pretty complex and dynamic, with an ever-changing impact on the river's ecology and economy in the region.

3. How to measure water current of North (Great Lakes) River?

Some methods can be employed for the measurement of water current in the North Great Lakes River.

Velocity meter method: A conventional method in which water at a certain point of time is intercepted by placing a mechanical or electrical velocity meter in the water body. These meters usually consist of rotating impellers or other sensing elements that can detect the speed at which the water is flowing past them. This method, however, can be quite labor-intensive since the meters have to be manually deployed and retrieved at several points along the river, and may not provide a comprehensive picture of the entire flow profile across different depths and widths of the river.

ADCP Method: It is a more sophisticated and efficient technique for the measurement of water current. It measures simultaneously, with acoustic waves, the velocity of water at more different points in a water column. By emitting sound pulses and analyzing the Doppler shift of the reflected signals, it can obtain detailed information about the flow velocity distribution from the surface down to the riverbed. This enables a more accurate understanding of the current patterns of this river.

Buoy method: Buoys fitted with sensors can be installed in the river to measure the surface current. They can float along with the flow and transmit data about their position and movement over time. This method can give an indication of the surface flow, though it has limitations in providing information about the flow at deeper layers of the river.

Of these, ADCP is one of the favored tools as it provides more information and comprehensive data with relatively less effort compared to the other conventional methods.

4. How do ADCPs using the principle of the Doppler work?

Working on the principle of Doppler, ADCPs transmit acoustic pulses into the water. When these pulses encounter moving particles in the water-that is, sediment particles or small organisms-the frequency of the reflected sound waves shifts through the Doppler effect. Particles moving toward the ADCP profiler will shift the frequency of the reflected waves to a value higher than the emitted frequency, while particles moving away will shift the frequency to a lower value. This frequency shift is precisely measured, and, after some sophisticated algorithm manipulation, the ADCP calculates the velocity of the water at various points over its measurement range. The direction of the flow is deduced from the phase differences of the reflected signals from various directions. This will provide a detailed velocity profile, indicating the actual water flow in the horizontal direction at several depths and sections of the river.

5. What is necessary to measure the North, or Great Lakes, river currents with high quality?

Several aspects are crucial with respect to the equipment in high-quality measurements of the North or Great Lakes river currents. The material of the equipment should be reliable. Firstly, having a small size and light weight is advantageous as it makes the deployment and retrieval of the measuring devices easier, especially in different field conditions and from various types of vessels. Moreover, low power consumption is an indispensable prerequisite so as not to require frequent replacements of the battery or a large power source, especially when conducting a long-term monitoring of quite remote areas.

Costs are another critical factor: The lower the cost, the higher the feasibility to perform measurement on a large scale on various sections of the river. In the case of ADCP meter casing, the material of choice is titanium alloy. Titanium alloy possesses astonishing properties. It is highly resistant to corrosion, which is so important when the equipment constantly interacts with water, and even more so in often harsh and variable water conditions of the North (Great Lakes) River. It also possesses a good strength-to-weight ratio, allowing for making the construction durable yet comparatively light. This helps in protecting the internal components of the ADCP without adding excessive weight that may complicate the deployment process.

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

When it comes to choosing the right equipment for current measurement in the North (Great Lakes) River, two aspects should be mainly considered.

First, according to the purpose of use, if the purpose is to perform horizontal cross-section measurements, then the horizontal ADCP-HADCP will be the suitable choice. It is designed for flow velocity measurement across a horizontal plane and yields valuable data on lateral water movement within the river. Vertical cross-section measurements are better accomplished with a vertical ADCP flow meter, which concentrates on the determination of flow velocity from the surface to the bed of the river along a vertical line, helping in the analysis of the vertical flow characteristic.

The frequency of ADCPs applied is suitable for different water depths. For example, the 600 kHz frequency ADCP current profiler is perfect for water depth within 70 meters. This is accurate for relatively shallow waters. The 300 kHz frequency ADCP will be better fitted for water depths up to 110 meters and allows one to collect reliable data in deeper parts of the river.

In the market, there are a number of popular brands of ADCPs like Teledyne RDI, Nortek, and Sontek. However, a very good Chinese brand of ADCP current meter is China Sonar PandaADCP. It has a casing fully made of titanium alloy, featuring excellent strength with anti-corrosion. More importantly, the cost-performance ratio is incredibly good; it's very attractive for anyone who wants to conduct high-quality current measurements in the North River (Great Lakes). Further information about it can be found on its official website: https://china-sonar.com/.

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