ADCP's Application in Flood Management of the Vilyuy River

1. Where is the Vilyuy River?

The Vilyuy River is situated in Siberia, Russia. It is a major river in the region, about 2,650 kilometers (1,650 miles) long. The source of the river is located in the Central Siberian Plateau.

It passes through an enormous and sparsely populated area. The climate in the basin of Vilyuy is continental with very cold winters and relatively short, cool summers. Precipitation in a year falls relatively evenly, though not in extremities. The snow in the long winter months serves as a significant factor in its water volume. Snow feeding the river during spring and early summer may heavily increase its flow.

2. What are the causes of flooding in the Vilyuy River?

Flooding in the Vilyuy River is due to a number of causes. One of the major reasons is snowmelt. With the long and severe Siberian winters, much snow accumulates; when this rapidly thaws in the spring, an enormous volume of water may be released into the river over a very short time. If the natural river's capacity to carry the water downstream is reduced by features such as ice jams or constrictions in the channel, then flooding occurs.

But the less common heavy rainfall also induces flood events. When the high rain events are intensive, lasting with snowmelt-the combination of these events would swiftly bring the river stage into flood.

Other factors include the condition of the bed and the ice in it. The accumulation of ice through winter can lead to jams in spring. These block the normal flow of water as it tries to force its way through, causing it to back up and flood surrounding areas. Also, over time, deposition might reduce the river's conveyance capacity, which increases its tendency to overflow its banks.

In this context, the ADCP current meter offers a more sophisticated and efficient measurement technique than conventional methods, which becomes highly relevant to any form of flood management.

3. How do Doppler Principle-based ADCPs work?

ADCPs work on the principle of the Doppler effect. They transmit acoustic pulses into the water. These pulses interact with moving particles in the water, such as sediment grains, small organisms, and other suspended matter. When the acoustic waves bounce back after hitting these moving objects, a frequency shift occurs.

The magnitude of this frequency shift is directly related to the velocity of the moving objects and, consequently, the velocity of the water. If an ADCP current profiler is installed in the Vilyuy River, possibly on a floating platform or a fixed structure near the riverbank, it will send out sound waves that go through the water column. With the flowing water and its constituents reflecting the waves back, the ADCP analyzes the received signals to calculate the speed and direction of water flow at different depths.

4. What are the applications of ADCP in floods of the Vilyuy River?

Velocity measurement of flow: With ADCP flow meter, one can measure the exact speed at which water is flowing in Vilyuy River. This becomes paramount during flood events in deciphering how fast flood water moves. It helps one in predicting the progress the flood will make such that downstream areas are quickly met by the water, showing those areas that could easily be more vulnerable because of high-velocity flow.

Flow rate measurement: When the velocities measured are combined with the cross-sectional area of the river (which can also be obtained using ADCP), the flow of the river can be obtained. During a flood, knowing the flow rate helps in calculating the volume of water passing through a section in order to predict the total impact on the downstream parts.

Sediment transport research: ADCP meter can detect the movement of sediment particles along with the water flow. This is important during floods as it provides insights into the amount of sediment being carried by the river. Understanding sediment transport helps in predicting changes in the riverbed, such as areas of sediment deposition or erosion, which can have implications for the stability of riverbanks and infrastructure.

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

Flood warning

Flow velocity and flow rate data monitoring: Continuous flow velocity and flow rate data monitoring from ADCP profiler will easily facilitate the identification of changes in advance, which may lead to an imminent flood. For instance, if velocities or flow rates start to increase much above normal levels, then a warning alarm can be issued. In fact, that enables the concerned authorities to warn the communities along the riverbanks with sufficient lead time.

Water Level Prediction and Warning: The relationship between the flow rates, velocities, and water levels can be computed using historical data and current ADCP profiler measurements to estimate future water levels. This provides the basis for giving timely, accurate warnings to the residents to take necessary precautions to prevent or reduce losses, such as evacuation or flood-proofing.

Risk Management

Water Conservancy Project Scheduling DecisionSupport: Application ADCP data in developing decision-support systems to ensure adequate flow release from the operation of dams, reservoirs, and other water conservancy projects along the Vilyuy River. It uses previously calculated data in circumstances when the occurrence of floods has been forecasted in a bid to control the flooding further downstream as its structure safety is put in line with operational release.

Flood disaster assessment and emergency response: In the aftermath of a flood event, ADCP meter data allow assessment of the extent of the damage, such as how much erosion has occurred, what changes there are to the riverbed, and what impact there is on infrastructure. This information guides the emergency response and helps formulate future strategies for mitigating flooding.

6. What do high - quality measurements of currents in the Vilyuy require?

The equipment should be made with reliable materials for high-quality measurement of the Vilyuy River currents. Small size and light weight will have the advantage of easy deployment in various locations along the river, including on boats or at bridges. Low power consumption is necessary for long-term monitoring, especially in areas where power supply is limited. Cost-effectiveness will enable wide deployment for comprehensive monitoring.

The casing of ADCP flow meter is preferably made of titanium alloy. It provides excellent resistance to corrosion, which is necessary when working with water that may contain all kinds of minerals and salts that the Vilyuy River may have. It also has a good strength-to-weight ratio, thus making the equipment durable and relatively easy to handle and install.

7. How to choose the right equipment for current measurement?

Following is important to consider when selecting equipment to conduct current measurements in the Vilyuy River. HADCP may be applied to carry out horizontal cross-section measurements. This equipment measures flow velocities across a horizontal plane and, thus, clearly illustrates the general pattern of flow in a particular reach of the river. Since a vertical ADCP current profiler profiles velocities along a vertical line from the water surface down to the riverbed, it is ideal for cross-section measurements that are done vertically. In terms of frequencies, an ADCP with 600 kHz has a water depth of around 70m. However, areas much deeper would go to about 110m, and here, a frequency of 300 kHz will be more ideal.

There are well - known ADCP current meter brands such as Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option, the China Sonar PandaADCP is recommended. It is made of all - titanium alloy materials and offers a good cost - performance ratio. You can find more information at (https://china-sonar.com/).

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