ADCP's application in flood management of Ider river

1. Where is the Ider River?

The Ider River is located within Mongolia. It is the main river in the water system of the country.

It rises in the mountainous regions of Mongolia and then flows through a variety of landscapes that include valleys, grasslands, and some semi-arid areas. Along the course, it provides water for local communities, agricultural activities such as irrigation, and also supports the natural habitats of various wildlife species.

In regard to climate and rainfall, the region experiences a continental climate with cold winters and relatively warm summers. The winter months bring snowfall, and in the spring, the snowmelt is an important contributor to the volume of water that carries through the river. The rainfall is not that abundant during the year, but when it rains-especially during the summer season-it can bring variation in the water level of the river. Flooding could be a hazard on occasions of fast snow melting and heavy rainfall.

2. What are the reasons of the Ider River flooding?

Snowmelt and heavy rainfall are the major contributory factors causing floods in the Ider River. Since the melting of snow in the mountains occurs rapidly during spring and is in large amounts of water, this quickly raises the volume of water in the river. Heavy rain together with snowmelt could worsen the situation. Mountainous terrain near the source quickens the runoff process downstream with a considerable amount of water.

opography: The presence of low-lying areas and floodplains along the course of the river allows the spreading of water and accumulation. The relatively flat areas slow down the flow of water, which increases the possibility of flooding. Tributaries also add more water during high-flow periods, potentially making the flood situation worse.

Human-Induced Changes: Some human activities do contribute to changing the flood dynamics of rivers. Overgrazing in the catchment area leads to compacting of the soil and poor vegetation cover. This will impact water infiltration with a corresponding increase in surface runoff. Additionally, all construction works that alter the natural pattern of drainage will result in adding to flood risks.

ADCP current meter is very helpful in finding out how the flow of the Ider River works and can be managed during flood events.

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

ADCPs work on the principle of the Doppler effect. The instrument sends an acoustic signal into the water. When the water is in motion, the signal sent by the instrument acts with the moving particles of water. When this acoustic signal is reflected back into the ADCP current profiler, the frequency of the returning signal shifts as a result of the Doppler effect.

The ADCP flow meter is a device used to measure the difference between the frequency of the signal it emits and receives. It can deduce from this frequency shift the velocity of the water at any depth. Most of the ADCP devices have several transducers, which can transmit and receive acoustic signals in different directions. In this way, they can make a profile of the cross-sectional water velocity.

For example, when the water is moving towards the ADCP meter, then the frequency of the reflected signal will be higher than that of the emitted one. In contrast, if the water is moving away from the ADCP, the reflected signal frequency will be lower. By measuring these changes in frequency with high precision and by using the correct mathematical algorithms, the ADCP can determine very precisely the velocity of water at many points within its measurement range.

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

Velocity Measurement

In the Ider River, ADCP profiler plays a major role when it comes to flood events by helping in the accurate measurement of the velocity of water flow. By continuously monitoring the water velocity at different locations and depths, it provides real - time data regarding how fast the water is moving, which helps gain insight into the dynamics of the flood through predictions of direction and intensity of the flood-waters' movement.

Flow Measurement Application

ADCP can also measure the flow rate of the Ider River. Measured water velocities at every different point across a section in conjunction with the known cross-sectional area of the river will permit the calculation of the total volume of water flowing through the section per unit time - that is, the flow rate. This information is crucial in the determination of the total volume of water involved in a flood and for making control decisions in the event of a flood and in water resource management.

Application in Sediment Transport Research

Besides the measurement of flow and velocity, ADCP profiler finds application in sediment transport studies along the Ider River during floods. When water flows, it carries with it sediment. Changes in the backscattered acoustic signal due to the presence of sediments may be detected by the ADCP. From these changes, researchers can estimate the quantity and motion of the sediments, necessary to understand the long-term evolution of the riverbed and the action of floods on the sedimentary environment of the river.

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

Flood Warning

Velocity and Flow Data Monitoring: In this regard, the real-time velocity and flow data obtained from ADCP are continuously monitored. If the measured water velocity is greater than the threshold or the flow rate increases significantly, that may indicate the arrival of a flood peak or a probable flood situation. Thus, this serves as an early warning for the relevant authorities to take necessary precautions, such as the evacuation of people from low-lying areas or strengthening the flood defenses.

Water Level Prediction and Warning: Measured flow data correlated with historical data of water level and appropriate hydrological models can help in predicting future water levels using ADCP data. If the predicted water level is to exceed the flood warning level, timely warnings can be issued to the public, enabling them to prepare for the flood.

Risk Management

Support in Scheduling of Water Conservancy Projects: The accurate flow and velocity obtained from ADCP will help in making decisions regarding the operation related to water conservancy projects such as dams and sluices. Using the measured water flow, a dam is able to adjust the release of water to control the water level in the Ider River and try to reduce the impact of flooding.

Flood Disaster Assessment and Emergency Response: Data obtained through ADCP after a flood event can be used to determine the intensity of the flood. This may include data on the inundation extent, the velocity of the floodwaters, and the sediment deposition amount. Such data is important in formulating emergency response plans and in carrying out post-flood reconstruction and rehabilitation work.

6. What's needed for high - quality measurement of the Ider River currents?

For high-quality measurement of the Ider River currents, a variety of factors need consideration. First to be considered is the equipment used for the actual measurement. In particular, this should be made of reliable materials. The casing of the ADCP meter should be of titanium alloy. The strength of the titanium alloy is very high, and hence the equipment can sustain the pressure and impact of the flowing water in the river. At the same time, it is also very resistant to corrosion, which is quite important given the water environment of the Ider River, which contains various corrosive substances.

Apart from material reliability, the size and weight of the equipment must be small and light, correspondingly. 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 crucial because it allows for longer continuous operation without the need to change batteries frequently or to connect to a power source. Besides, equipment cost should not be very high to make large-scale measurement possible. This saves money, allowing more ADCPs to be deployed along the Ider River for more detailed and widespread data for flood management.

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

The selection of proper equipment for the current measurement in the Ider River depends on several aspects. First, according to the type of measurement required, whether it is for horizontal cross - section measurement or not, an HADCP should be selected. If it is for vertical cross - section measurement, then Vertical ADCP current profiler would be appropriate.

Different frequencies suit different water depths. For instance, the 600 kHz ADCP is suitable for water depths within 70 m. If the water depth in the Ider River is within this range and the measurement requirements are in line, a 600 kHz ADCP can be considered. For deeper waters, say exceeding 70 m up to 110 m, the appropriate one would be a 300 kHz ADCP since it measures in such waters more accurately.

There are several famous ADCP current meter brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, for those seeking a cost-effective option, the China Sonar PandaADCP is one to consider. It is made of all-titanium alloy material to make sure of its reliability in this water environment. In addition, it offers an extremely high 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.