ADCP's application in flood management of Ob River

1. Location of Ob River

The Ob River is a major river in Russia. Its source is in the Altai Mountains. As it flows north, it crosses a large area of Western Siberia.

In its course, the river flows through different landscapes: from mountainous areas near its source, through vast taiga forests, to huge flood areas. The Ob River is an important watercourse supplying water for various purposes, including domestic water supply, industrial use, and agricultural irrigation, to the regions through which the river flows.

From the viewpoint of climate and rainfall, the regions that are crossed by the Ob River exhibit a continental climate. The winters are long and very cold, accompanied by heavy snowfall in the upper reaches as well as most of its catchment area. Spring and summer bring snow melting and rains. Snow melting from the mountains and the large catchment area contributes much to the volume of water the river carries. This can create serious fluctuations in the water level; during heavy precipitation or with quick snowmelt, it may result in flooding of some facilities.

2. What are the causes of floods in the Ob River?

Snowmelt and Heavy Rainfall: Spring snow melting and high rainfall from the wet season provide the chief causes of flooding. The huge volumes of meltwater from snow in the Altai Mountains and the large catchment area, plus extra rain water, can raise the water volume of the river very quickly. The mountainous catchment area next to its source accelerates the runoff downstream and channels a large amount of water.

Topography: The wide floodplains and low-lying areas along its course have given it the capability to spread out and collect water. The generally flat plains slow the flow of water, thereby giving the water a better chance of flooding. Where many tributaries join this river, the extra water they contribute during high-flow conditions increases the flood situation.

Human-induced changes: Deforestation in the catchment area reduces the capacity of the forest for interception and retention of rainwater. It causes soil erosion; this eroded soil gets deposited in the river, thereby decreasing the river's carrying capacity. The construction of dams and other infrastructure related to water sometimes disrupts the pattern of natural water flow and drainage, therefore enhancing flood risk in certain areas.

ADCP current meter is a very useful tool in understanding the flow of the Ob River and adopting various control measures during its flooding.

3. How do ADCPs using the principle of Doppler work?

The operation of ADCPs is based on the principle of Doppler. A device sends out an acoustic signal into the water. Because the water is flowing, the signal collides with the moving particles of water. When this acoustic signal is reflected back to the ADCP current profiler, the frequency of the returning signal is shifted by the Doppler effect.

The ADCP measures the differential frequency between the emitted signal and the received signal. By analyzing this frequency shift, it calculates the velocity of the water at different depths. These devices usually have several transducers that can emit and receive acoustic signals in different directions. In this way, they can make a profile of the water velocity across a section of the river.

For instance, if the water flows towards the ADCP flow meter, then the frequency of the reflected signal will be higher than that emitted. On the other hand, when the water is flowing away from the ADCP, the reflected signal has a lower frequency. By accurately measuring these changes in frequency, using the proper mathematical algorithms enables the ADCP to determine, with great accuracy, the velocity at several points within the measurement range.

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

Velocity Measurement

In the Ob River, ADCP is very critical for flood events as it measures the water flow's velocity. At shallow waters and variable locations, continuously monitoring the water current velocity it transmits real-time data on the rate of movement of water. Such becomes of great importance to understand the dynamics of the flood on, pre-diction of the direction and intensity of the floodwaters' movement.

Flow Measurement Application

ADCP profiler is also capable of measuring the flow rate of the Ob River. Knowing the cross-sectional area of the river and combining the measured water velocities at different points across a section of the river will enable the calculation of the total volume of water flowing through that section per unit time, which is the flow rate. Such data is fundamental when it comes to assessing the general water volume within the flood and in making various decisions regarding flood control and water resource management.

Application in Sediment Transport Research

Besides flow and velocity measurements, ADCP can be applied in the study of sediment transport in the Ob River during floods. The water, in its move, carries sediments. The ADCP may detect changes in the backscattered acoustic signal due to the presence of sediments. By analyzing these changes, researchers are able to estimate the amount and motion of sediments. This is an important key for assessing the long-term evolution of the riverbed and the impact of floods on the sedimentary environment of the river.

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

Flood Warning

Velocity and Flow Data Monitoring: Continuously, the real-time data obtained by ADCP meter about velocity and flow are monitored. If the measured water velocity is more than a threshold or the flow rate has a sudden rise, it may indicate that either the flood peak is approaching or the possibility of a flood situation is there. This early warning enables relevant authorities to take their preventive measures for evacuation in the low-lying areas or strengthening flood defenses.

Water Level Prediction and Warning: ADCP data may be used to predict the future water level from the correlation of measured flow data with historical water level data using appropriate hydrological models. If the predicted water level is expected to surpass the flood warning level, warnings can be timely issued to the public in order to prepare for the flood.

Risk Management

Water Conservancy Project Scheduling Decisions Support: The flow and velocity data obtained using ADCP will be able to aid the decision-making process for the operation of the water conservancy projects, namely, dams and sluices. For instance, depending on the intensity of water flow measured, it is possible to regulate the release of water from the dam to control the water level in the Ob River and reduce the impact of floods.

Assessment of Flood Disaster and Implementation of Emergency Response: The ADCP profiler recording during a flood event will help assess the magnitude of the flood - the extent of inundation, the velocity of flood flow, and quantity of sediment deposition. Such information is of importance in formulating emergency response plans and for carrying out post-flood reconstruction and rehabilitation works.

6. What is necessary for high-quality measurement of the Ob River currents?

The high-quality measurement of currents in the Ob River has several factors that should be considered. The first is that the equipment used should have reliable materials. This concern refers mainly to the casing of the ADCP meter. The casing should be recommended to be made from a titanium alloy. The titanium alloy is a high-strength alloy that allows the equipment to bear the pressure and impact of the water flowing in the river, while its corrosion resistance is very high. This is important considering the water environment in the Ob River, which might contain many corrosive substances.

Besides material reliability, the size and weight of the equipment should also be small and light. This makes it easier to install and operate the ADCP flow meter in different locations along the river, especially in areas that are difficult to access. Low power consumption is also very important because it can keep longer continuous operation without frequent battery replacement or connection with a power source. Besides, the equipment cost needs to be relatively low to enable large-scale measurement. A reduced cost, however, allows the deployment of more ADCPs in the Ob River to provide more detailed and comprehensive data in flood management.

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

When choosing the right equipment for current measurement in the Ob River, several aspects need to be taken into account. Firstly, depending on the type of measurement required, if it is for horizontal cross - section measurement, a Horizontal ADCP current profiler (HADCP) should be selected. On the other hand, if it is for vertical cross - section measurement, a Vertical ADCP current meter is the appropriate choice.

The different frequencies used correspond to different water depths. A 600 kHz ADCP, for instance, is suitable for water within 70 m depth. If the water depth in Ob River is within this depth and matches the measurement requirements of the instrument, a 600 kHz ADCP can be considered. But for deeper waters, such as those over 70 m and up to 110 m, a 300 kHz ADCP is more suitable since this device provides more accurate reading at that depth.

There are several known brands of ADCPs available in the market. These include Teledyne RDI, Nortek, Sontek, among others. However, for more budget-friendly options, China Sonar PandaADCP is one of the best options. It is made of all - titanium alloy material, which ensures its durability and reliability in the water environment. Moreover, it 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.