ADCP's Application in Flood Management of Ob River

1. Where is Ob River?

The Ob River is one of the major rivers in Russia, having its origin in the Altai Mountains. It flows northward across the vast West Siberian Plain, traversing through numerous regions and playing a significant role in the local ecosystem and economy.

It flows past several major cities and towns, including Novosibirsk, a significant industrial and cultural center in Siberia. The Ob River runs its course under the conditions of a continental climate, which means pronounced seasons. The rainfall is not particularly high, but during the long winter months, snowfall is considerable. During spring, when this snow melts, it adds a lot to the water in the river, often resulting in higher-than-normal water levels and possible flooding situations.

This is a big basin covering most of the area in the West Siberian region. The topography surrounding the river varies from mountainous near its source to flat plains further downstream, which influences the flow characteristics and flood behavior of the Ob River.

2. What are the Reasons for Floods in Ob River?

Snowmelt: A great amount of snow falls during the long winter in Siberia; during spring, it melts. The fast melting may turn out a huge volume of water within a relatively short period of time into the Ob River. In such a case, if its natural drainage capacity is less than this sudden surge of water, then the water level will come up, and there are chances of floods. A case in point is a year when more than average snowfall occurs or at an increased melting rate due to high temperatures in spring.

Topography: The flat landscape of the West Siberian Plain, in which the Ob River runs for most of its length, reduces the flow velocity of the water. This allows more water to be stored and spread out over a larger area during high water. Moreover, the presence of floodplains and meandering reaches can also affect how water behaves during flood events and may contribute to the inundation of adjacent land.

Rainfall Patterns: The average rainfall in the area may not be very high, but rainfall events can be intense and long in wet seasons, adding to the water volume in the river. When combined with snowmelt water or when the river is already close to carrying its full capacity, such rainfall acts as a trigger or increases flood intensities.

In this context of the flood risks management, Acoustic Doppler Current Profiler (ADCP) emerges to be a more progressive and efficient tool in monitoring the flow characteristic closely in the river.

3. Working of ADCPs Based on the Doppler Principle

ADCPs utilize the principle of Doppler. They send out an acoustic signal into the Ob River water. When these acoustic waves interact with moving particles in the water-such as sediment particles or small aquatic organisms-being carried along by the flow, the frequency of the reflected waves is different from the frequency of the emitted waves. The shift in frequency, called the Doppler shift, is directly proportional to the velocity of the moving particles and, by extension, to the velocity of the water flow.

Because it employs numerous acoustic beams transmitted at a different angled and received echoes from reflected signal, ADCP current meter was able to measure the current in any specific place inside the water column and was able to read through with different depths and flow speed by combining advance sophisticated algorithm of these acquired signals in order to work out complete information of current velocity profile needed to ascertain the hydrodynamical characteristics of the Ob River.

4. What are the Applications of ADCP in Floods of Ob River?

Velocity Measurement: In cases of flood or high water flow in the Ob River, ADCP flow meter will be able to measure the velocity of the water at every different point of the river with great accuracy. This information is crucial in order to know the erosive power of the flood waters. For instance, high flow velocities along riverbanks can indicate areas where bank erosion is likely to occur, enabling appropriate preventive measures to be taken, such as strengthening the banks or implementing erosion control structures.

Flow Measurement Application: By integrating the measured velocity data over the cross-sectional area of the river, ADCP profiler can calculate the flow rate of the Ob River. This is very important in the handling of floodwaters, as the authorities would know the quantity of water passing through a specific portion of the river. Based on that information, decisions can be taken about the flood control measure, whether to open or close the floodgates of the reservoir or alter the operation of the water diversion channel.

Sediment Transport Research: The Ob River carries a huge amount of sediment. ADCP current profiler can be used in studying the transportation of sediment during flood periods. Analysis of the relations between water flow velocity and sediment concentration and movement pattern could interpret the way floods affect sedimentation and erosion processes in the river and, therefore, is helpful in maintaining the health of the riverbed and the overall ecological balance of the river system.

5. How can the data measured by ADCP be used in flood warning and risk management of Ob River?

Flood Warning

Velocity and Flow Data Monitoring: Continuous monitoring of water flow velocity and flow rate by ADCP flow meter provides real-time data. When these measured values exceed certain predefined thresholds, it can serve as an early warning signal for an impending flood. For example, if the flow rate at a key monitoring point on the Ob River suddenly starts to increase rapidly and approaches the historical flood level flow rate, it triggers an alarm to alert the local communities and relevant departments.

Water Level Prediction and Warning: The velocity data from ADCP profiler can be combined with other hydrological models in order to predict the water levels of the future. By establishing a relationship between flow velocity and change in water level, one could get better forecasts of when and by how much the water would rise, giving people ample time to prepare for any flooding that might occur.

Risk Management

Water Conservancy Project Scheduling Decision Support: The data from ADCP flow meter is very useful in deciding on the operation of conservancy projects in the Ob River, for instance, dams and reservoirs.

For example, if the measured flow indicates that a large flood is coming, the reservoir manager may elect to make pre-release in order to create space for the arriving floodwater, minimizing the chance of overtopping and resulting in the project's safety.

Flood Disaster Assessment and Emergency Response: In the event of a flood, the ADCP data is utilized to evaluate the effect of the flood in terms of the area eroded, deposition in various locations, and morphological changes to the river channel. Such information is of paramount importance when planning the necessary emergency responses and post-disaster recovery processes.

6. What's Needed for High-Quality Measurement of Ob River Currents?

Several factors have to be considered in order to make high-quality measurements of the Ob River currents: first, the equipment should be highly material-reliable. Considering the cold climate and long harsh winters, and taking into account that in different seasons there may be ice and debris in the river, only materials that are resistant to such conditions can be used.

Secondly, a smaller size, lighter weight, and low power consumption are preferable. Compact and lightweight ADCP meter is easy to install and deploy at different locations along the river, including remote areas.

Low power consumption will provide longer continuous operations without frequently replacing the power source or undertaking maintenance activities, which again is vital for large-scale and long-term monitoring. Besides, a lower cost is preferred to enable the use of more pieces of equipment in the comprehensive measurement of the river. When it comes to the casing of ADCP flow meter, titanium alloy is a good option. The advantages of using a titanium alloy are numerous.

It is highly strong and thus able to withstand the mechanical forces exerted by the flowing water, ice impacts, and collisions with debris. It also has very good corrosion resistance, important in the aquatic environment of the Ob River, possibly with many chemical substances and long-term moistening. This helps to make sure the performance of the ADCP current meter is stable and accurate for long periods.

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

Based on the Usage Purpose: If the measurement is focused on the horizontal cross-section of the river, the horizontal ADCP, or HADCP, is more suitable. It can provide detailed information about the flow velocity distribution across the horizontal plane of the river section, which is useful for understanding the overall flow pattern. In the case of vertical cross-section measurement, a vertical ADCP should be selected because it is designed to measure the velocity profile in the vertical direction precisely, which helps analyze the variation of flow velocity with depth.

Based on Different Frequencies: Different frequencies of ADCPs are suitable for different water depth ranges. For example, an ADCP with a frequency of 600 kHz is typically appropriate for water depths within 70 meters.

It can give relatively accurate measurements in the shallower to moderately deep waters of the Ob River. While an ADCP with a frequency of 300 kHz is more suitable for water depths up to 110 meters, making it a good choice for deeper sections of the river where a more detailed velocity profile is needed. There are several well-known ADCP flow meter brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective option, it is highly recommended to check out the China Sonar PandaADCP. It is made entirely of titanium alloy material, which not only ensures its durability but also offers an incredible cost-performance ratio. You can find out more about it on its official website: (https://china-sonar.com/).

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