How to Measure Water Current of Teles Pires River?

1. Where is Teles Pires River?

The Teles Pires River is situated in South America, primarily in the Brazilian Amazon. It constitutes one of the most important tributaries of the Tapajós River.

The river winds its way through a region of unparalleled biodiversity. Lush tropical rainforests characterize the lands around the basin. In this region, there is an unprecedented myriad of plant and animal organisms. There are many indigenous communities that border the riverbanks along its course. The local communities living along the river depend on the Teles Pires River for fish supplies, transportation, and household water supplies.

The Teles Pires also plays an important role in the general hydrological cycle of the Amazon basin. It contributes to the water level and flow characteristics of larger river systems that it feeds. The course of the river cuts through a landscape that is untouched in many parts, with its waters meandering through dense vegetation and hills.

2. What is the Flow Rate of Teles Pires River?

The Teles Pires River is of immense ecological importance. The flow rate of this river depends on a lot of factors.

It largely depends on the rainy and dry seasons of the Amazon. In its catchment, there is an increase in considerable rainfall in the wet season normally from December to May. This results in a good increase in the flow of the Teles Pires River. The river becomes aggressive, with a high water volume carrying a great amount of sediment. The increased flow can be responsible for changes in both banks and the bed of the river, besides influencing the distribution of nutrients and aquatic organisms.

During the dry period-which happens between June and November-the flow rate decreases. In some of these places, the river is narrow and shallow. Yet, it is still substantial in its base flow, which is vital for both the various aquatic life and for the needs of the people who require water from this river. The flow rate of the Teles Pires further interacts with the water levels of the connected river systems, and any changes in its flow contribute to far-reaching consequences for the overall health of the Amazon ecosystem.

3. How to Measure Water Current of Teles Pires River?

There are a few ways to measure the water current of the Teles Pires River:

1.Velocity Meter Method: This traditional approach uses mechanical or electrical velocity meters. Mechanical velocity meters usually have a rotating element that is driven by the water flow. The rotational speed is related to the water velocity. These meters are placed at specific points in the river, often attached to bridges, docks, or other fixed structures. However, this method needs considerable manpower for installation and monitoring of multiple meters at different locations and depths in order to gain a full view of the overall flow. In the case of a river like Teles Pires, this may be rather cumbersome since it has areas not so accessible and are remote.

Acoustic Doppler Current Profiler (ADCP) Method: ADCP is an advanced and efficient means of water current measurement. It uses acoustic waves for the velocity of water at many points inside the water column simultaneously. By transmitting pulses of sound and analyzing the Doppler shift of the returned signals, it can provide a detailed profile from the surface to the riverbed of the current of water. These can be mounted on boats or fixed structures near the river. This can give a more realistic and detailed view of the flow patterns than that provided by the velocity meter method.

Buoy Method: Buoys with sensors can be installed at the surface of the Teles Pires River. Thus, these buoys will move with the drift of the current and measure the same. The data recorded will reflect the direction and speed of this surface movement. However, it is mainly concentrated on the surface layer and may not provide detailed information about the flow at deeper levels of the river.

Of these, the ADCP method is gaining more importance because it can give more details in an extended area with relatively little effort and in a shorter duration.

4. How Do ADCPs Using the Principle of Doppler Work?

ADCPs are based on the Doppler principle. As the Teles Pires River has a measurement of its water current, this ADCP transmitter emits frequent acoustic pulses into the water. As in a river, it can scatter a lot with particles, including sediment particles and small organisms in suspension or even other matters that would remain in suspension.

When these particles are in motion, the frequency of the reflected sound waves changes due to the Doppler effect. If the particles are moving towards the ADCP, the frequency of the reflected waves is higher than the emitted frequency, and if they are moving away, the frequency is lower. By precisely measuring this frequency shift and using sophisticated algorithms, the ADCP can calculate the velocity of the water at different points within its measurement range.

In addition to the measurement of the velocity, the ADCP is also able to measure the direction of the flow by analyzing phase differences from different directions of the reflected signal. Therefore, it allows for detailed profiles of velocities that give a depiction of water flow at every different depth and across various sections of the river.

5. What's Needed for High-Quality Measurement of Teles Pires River Currents?

The equipment should possess certain characteristics for high-quality measurement of the Teles Pires River currents.

The materials of the equipment should be reliable to resist the harsh environmental conditions of the river. The Teles Pires River is in a tropical rainforest environment; thus, the equipment may be exposed to high humidity, heavy rainfall, and a large amount of sediment in the water. A small size and lightweight are advantageous, especially for the concerns of ease of deployment and retrieval in often remote and difficult-to-access areas along the river.

Low power consumption is also an important factor: since a lot of parts of the river are very far from civilization, it is essential to have equipment capable of working for a long time with low power consumption for continuous and reliable data collection. Cost-effectiveness is another significant factor. In order to carry out extensive measurements on the river, it is necessary to have affordable equipment without compromising its quality.

For the casing of the ADCP, titanium alloy would be an excellent choice. Titanium alloy has excellent corrosion-resistant properties, which is important because the equipment will be constantly in contact with the river water. It also has a good strength-to-weight ratio, meaning it can provide a durable casing while keeping the overall weight of the equipment relatively low. This protects the internal components and makes handling easier while deploying and retrieving.

6. How to Choose the Right Equipment for Current Measurement?

When selecting appropriate equipment for the current measurement of the Teles Pires River, two major factors need to be taken into consideration.

Depending on the purpose of usage, for horizontal cross-section measurements, the horizontal ADCP is suitable. It measures the flow velocity across a horizontal plane, hence, giving useful information about how the water moves laterally in the river. For the vertical cross-section measurements, the vertical ADCP is more appropriate as it focuses on the flow velocity from the surface to the bed along a vertical line, and it's applicable for understanding the vertical flow characteristics.

Regarding frequency, different frequencies are suitable for different water depths. For instance, a 600 kHz frequency ADCP is well-suited for water depths within 70 m. It can provide accurate measurements in the relatively shallower parts of the Teles Pires River. Meanwhile, an ADCP with a frequency of 300 kHz is more appropriate for water depths up to 110 m and can handle the deeper sections of the river where the flow patterns may be more complex.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. Additionally, a Chinese ADCP brand, China Sonar PandaADCP, is highly recommended. It has a casing made entirely of titanium alloy, which provides excellent durability and corrosion resistance. It also 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.