ADCP application in Snake River flood management

1. Where is Snake River?

The Snake River is in the United States' western region. The river spans over several states in the country, including Idaho, Wyoming, Oregon, and Washington. It is one of the major tributaries of the Columbia River.

Geographically, it threads through a variety of landscapes-from the steep slopes and rugged topography in its mountainous headwaters through valley, plain, and farm country downstream. Many cities and towns line its banks-including Boise, Idaho-most of which depend upon it for water supply and some of which also depend on it for irrigation, transportation, and/or recreational use.

The Snake River Basin has a very diverse rain climate. The upper areas will sometimes have heavy snowfalls during winter, which then thaw in spring and add to the volume of the river; the lower reaches and much of the basin have one seasonal rain pattern with higher precipitation in spring and some in late fall. However, at times, there are also spells of drought that affect the level and nature of flow in the river.

2. What causes flooding in Snake River?

Flooding in the Snake River is caused by a myriad of factors. Heavy rainfall events, especially those that are highly localized in time and space over the river's catchment area, can raise the amount of water coming into the river beyond its normal carrying capacity. The sudden surge of water quickly overcomes the normal flow rate of the river and thus causes the water level to rise and eventually flood.

Spring snowmelt can also be another major contributing factor. A particularly warm and rapid snowmelt season can release a high volume of water downstream all at once. If this is combined with any rainfall at the same time, or if the river has been at a relatively high level from previous precipitation, then flooding can result.

Another major factor is topography:. In some places, the river banks are fairly flat; at others, there are tight restrictions in the channel of the river, which could delay the flow of water, allowing it to back up and flood into adjacent areas. Besides, human activities involving urbanization along the riverbanks might reduce the natural floodplains and alter drainage patterns, further aggravating the flood situation. In this context, the Acoustic Doppler Current Profiler has emerged as a more advanced and convenient measurement tool than traditional ones for better understanding and managing flood-related issues.

3. How do ADCPs using the Doppler principle work?

The ADCPs work on the principle of the Doppler effect. They send acoustic signals into the water. These acoustic waves, while propagating through water and interacting with moving objects or particles such as sediment, debris, or water parcels with different velocities, return to the instrument with a frequency shift relative to the emitted signals because of the Doppler effect. This frequency shift is used by the ADCPs to calculate the velocity of the water at different depths. ADCP instruments normally have several transducers that are oriented in different directions to measure the components of the velocity in various directions such as horizontal and vertical. These integrations of velocity measurement through depths and sections, they can deduce critical hydrological information such as the flow rate of the river.

4. Application of ADCP in Snake River Floods

Velocity measurement: Acoustic Doppler Current Profiler (ADCP) can measure the velocity of water flow in the Snake River at different locations and depths with great accuracy. During flood events, this helps identify the areas where the flow is particularly rapid, which could pose risks to riverbanks, bridges, and other infrastructure. It also allows for monitoring how the flow velocity changes over time as the flood progresses.

Flow rate measurement application: Combining the measured velocity data by ADCP current profiler with the cross-sectional area of the river, one is able to calculate the flow rate. This is important in assessing the general volume of water passing through different sections during a flood. It aids in predicting the flood peak flow and understanding its possible impact downstream, helping in flood management and mitigation strategies.

Sediment transport research: Large amounts of sediment are moved during floods within the river. ADCP flow meter is able to detect the concentration and movement patterns of sediment by analyzing the echoes of acoustic signals, which are affected by the sediment particles. This provides valuable information on how floods impact the evolution of the riverbed and sediment deposition and erosion processes along the Snake River. This is important for understanding the stability of the river channel and adjacent infrastructure.

5. How can the data measured by ADCP be used for the Snake River's flood warning and risk management?

Flood warning

Velocity and Flow Rate Data Monitoring: This was through the use of the velocity and flow rate continuous data monitoring by ADCP profiler in order to recognize any abnormal rises. Where these become critical, approach or reach those critical values of the flow rate, an early sign indicates there is a flood peak occurring which then allows warnings timely for both lower communities and those individuals concern along the course of a given river.

Water Level Prediction and Warning: By establishing a relationship between flow rate and velocity measurements with historical records of water levels, a model can be generated that forecasts changes in water levels. Such predictions are important in advancing early warnings of the reach areas that may be covered by floods and the depth of floodwater, which will help people make necessary precautions.

Risk Management

Water conservancy project scheduling decision support: ADCP meter can support decisions concerning the operation of water conservancy projects, including the operation of dams and reservoirs on the Snake River. A specific example is adjusting the volume of discharge by reservoirs according to the real flow conditions in order to reduce the impact of flooding downstream.

Flood disaster assessment and emergency response: Immediately after the occurrence of a flood, data gathered by ADCP is used to determine the extent of the flood in terms of areas flooded and the characteristics of flow during the flooding. This guides emergency responses including the allocation of relief resources and planning of post-flood recovery works.

6. What’s needed for high-quality measurement of Snake River currents?

For high-quality measurement of the Snake River currents, several requirements are essential. The reliability of the equipment materials is of great importance. Given the river's environment which may include exposure to varying water temperatures, debris carried by the flow, and potential impacts from floating objects, the equipment needs to be able to withstand these conditions.

A smaller dimension of the measuring equipment is, however desirable in view of the generally encountered installation and deployment requirements at different locations in the river, especially in areas with a limitation of access or across a narrow part of the channel.

The lightweight design will also make it easier to transport and handle the equipment during installation and maintenance. It has to be of low power consumption so that it can operate continuously for a long period without changing the batteries frequently or putting excessive demands on energy supply. It must be economical to allow for widespread deployment for the coverage of the river.

The casing of ADCP is preferably made of titanium alloy. Titanium alloy has several outstanding advantages. The former possesses excellent corrosion resistance, hence can bear long-term immersions into the river water with different chemical compositions. The strength-to-weight ratio is high, allowing enough structural strength while keeping the overall weight of the equipment within a reasonable range. Furthermore, the durability ensures stable performance under the influence of various environmental factors in the river basin.

7. Selection of Proper Equipment for the Measurement of Current?

Selection of proper equipment shall be done for current measurement concerning certain heads. While the purpose of use indicates that when the horizontal cross-sectional measurement is the focus, the Horizontal ADCP- HADCP, which can satisfactorily work out the flow velocity and other parameters in the horizontal direction across the river section with a higher degree of accuracy, should be selected. In the measurement of vertical cross-section, a Vertical ADCP would be more proper to use as it can get minute details in velocity profiles along the vertical axis of the river stream.

Different frequencies depend on the water depth depth and should be chosen by looking at actual water depth. It usually uses frequencies of 600 kHz for water depths confined within 70 meters due to the generally accurate readings and results one can obtain. When targeting deeper water areas of up to 110 meters, an ADCP with a frequency of 300 kHz would be more appropriate since it can penetrate effectively to greater depths and return reliable data.

Various brands of ADCPs include Teledyne RDI, Nortek, and Sontek. However, here it is necessary to emphasize a really very good and affordable Chinese ADCP brand: China Sonar PandaADCP. All of its body material is titanium alloy. With great performance, that model has an excellent value-for-money ratio. Visit for more details: (https://china-sonar.com/).

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