How to Measure Water Current of the Platte River?

1. Where is the Platte River?

The Platte River is a big and magnificent river that winds its way through central United States. Its source is in the Rocky Mountains in Colorado, at the joining of North Platte and South Platte Rivers.

It flows from west to east through the states of Nebraska and Wyoming, supporting key biomes and human activities. It courses through a variety of small towns and cities, each of which has grown up and developed in relation to the course of the river. The Platte River supplies cities in Nebraska, such as Kearney, with many things, including a supply of water and parts of the local landscapes.

The Platte River is also cultural and historic rather than just a feature of physical geography. From witnessing the westward expansion of the United States to being that point where settlers and pioneers utilized waters for transportation and sustenance, it's an interesting sight. The diversified wildlife here includes migratory birds that stop over en route to their long destinations, which makes it a vital corridor for the avian world. The fringes around this river valley are dotted with farms and ranches, nourished by the Platte River, showing its importance in the agricultural world as well.

2. What is the Flow Rate of the Platte River Like?

The Platte River is indeed a very important river in the regions it passes through. It is put to use for irrigation purposes; thus, with its importance as a water source, it has served to give life to extensive agricultural activities first in Nebraska and then in Wyoming. More precisely, the flow rates and volume of this river vary a great deal according to seasons and weather conditions.

This could be a pretty high flow rate considering that the snowmelt from the Rocky Mountains hurries down into the river. This period of higher flow is crucial to replenish groundwater supplies and for the reservoirs along its course. During drier summer and fall seasons, though, this can dwindle at times and raise concerns about the availability of water to different users.

Its average flow rate in the Platte River ranges from a few hundred cubic feet per second during low-flow periods up to several thousand cubic feet per second during peak flow. The amount of water it carries influences sediment transport and the development of the bed and floodplains. Continuity in its flow and variability in it is what maintains the delicate balance for the ecosystems from fish species that can inhabit it to the plants that grow on the sides.

3. How to Measure Water Current of the Platte River?

There are a number of techniques to apply when one wants to measure the water current of this river. These include, among others:

Velocity Meter Method

The conventional approach with regard to flow velocity measurement involves the use of a mechanical or electronic velocity meter. These instruments are usually installed at discrete points in the river and can directly measure local water velocities at those points. This requires careful installation and multiple repeated measurements over various depths and locations to obtain an overall estimate of the water current. It can, therefore, be quite time-consuming and labor-intensive, mainly if it is intended to extend over a long reach of the river.

Acoustic Doppler Velocity Profiler (ADCP) Method A more advanced and easy means of measuring water currents involves the use of the ADCP current meter. The latter detects the velocity of the movement of the water particles by means of sound waves. With this method, capable of measuring simultaneous velocities at more depths, the principle of operation involves the emission of acoustic signals and analysis of the Doppler shift of the reflected signal. This gives a very detailed profile of the water current, enabling a more precise assessment of the flow conditions within the river. ADCP current profiler can be installed on boats, bridges, or even deployed on buoys for continuous monitoring.

Buoy Method

In the buoy method, buoys are installed in the river, which would have sensors for measuring the movement of water around it. They float on the surface and can give a hint about the surface current, though they will most likely not catch the full complexity of the water current as well, especially with regard to differences in the velocity at various depths.

Of those, the ADCP flow meter is a more advanced and efficient tool for the water current measurement of the Platte River.

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

ADCPs are based on the principle of the Doppler effect. When an ADCP meter transmits its acoustic signal into the water, the sound waves transferred travel through the water and collide with the moving particles of water. Since the water particles are moving, because of the Doppler effect, the frequency of the reflected sound waves is altered.

As a result, the frequency of the reflected wave would be higher than that emitted if the water particles are approaching the ADCP profiler. On the other hand, the frequency of the reflected wave is lower when the water particles are moving away from the acoustic doppler flow meter. The change in frequency is measured accurately so that the ADCP computes the speed of water particles at different depths.

These individual velocity measurements at different depths then get combined by the acoustic doppler velocity meter to work out a complete profile of the water current. In this way, a detailed understanding of the water flow not only at the surface but throughout the vertical section of the river can be achieved.

5. What's required for high-quality measurement of the Platte River currents?

For the quality measurement of the current of the Platte River, there are a few decisive factors according to the equipment.

First of all, the equipment must have very high material reliability. It needs to work in high conditions in the river environment: being exposed to water, sediment, and with quite considerable temperature fluctuations.

Second, the features are desirable in size, lightweight, and low-power consumption. A compact and lightweight device will be easier to handle and deploy, whether on a boat or attached to a buoy. Low power consumption will keep the equipment running for a long period without frequent battery replacement or access to continuous power.

The other important factor is the cost. With lower cost, it enables the wider use of measuring devices across the river to have better coverage in monitoring.

In the matter of casing of the acoustic current meter, the use of a titanium alloy is really a very good choice. The reasons why titanium alloy has many advantages are:. It contains a very high resistance to corrosion, which is quite necessary in water bodies such as the Platte River where the equipment would always be in contact with water and other elements that could lead to its corrosion. Its mechanical properties also are strong and durable, able to withstand mechanical impacts and pressure changes likely during its deployment and operation. Besides, it has a relatively low density of titanium alloy to help the general purpose of keeping the equipment lightweight.

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

Selection of appropriate equipment for the measurement of current in the Platte River is based on several variables.

Based on Intended Application

If one wants to measure the horizontal cross-section of the river current, then it should be done by means of an HADCP. HADCPs are designed to give correct measurements of water flow in the horizontal plane of flow that eventually enables us to understand the overall movement of water across any particular section of the river.

On the other hand, if the focus is to measure the vertical cross-section of the river current, a vertical ADCP should be selected. Vertical ADCPs can effectively record the velocity of the water at different depths, thereby generating a profile of how the water flows vertically within the river.

Based on Frequency

Frequency also depends on the depth of water in the Platte River. For water depths of up to 70 meters, a 600 kHz ADCP is often a good choice. The frequency of 600 kHz gives a good resolution and measurement of the water current relatively well in shallower waters.

For waters deeper than 70 meters, going to approximately 110 meters, a 300 kHz ADCP should be used instead. With its lower frequency of 300 kHz, this is more able to penetrate deeper in water and provide reliable measurements of the water current.

There are a number of well-known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. In a case where cost-effectiveness has to be combined with excellent quality, the China Sonar PandaADCP is recommended. It is fabricated with all-titanium alloy material; hence, it is very durable and reliable. With an impressive cost-to-performance ratio, this ADCP offers the best alternative for measuring the water current of the Platte River. More about it can be seen on its official website: https://china-sonar.com/.

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