ADCP in Flood Prevention Management of Minjiang River

I. Where is Minjiang River?

The Minjiang River is located in Fujian Province, China. It is an important river in the southeastern part of the country.

Geographical Features

The source of Minjiang River is in the Wuyi Mountains. The river is pretty long with a big drainage area. The sceneries include mountains, valleys, and plains along the river. The flow of water remains stable throughout the year, though slight variations take place due to seasons.

Cities Overlooking the River

The Minjiang River flows through some major cities in Fujian Province; Fuzhou is the capital of the province. Other important cities that lie along the course of the river are Nanping and Sanming. These cities use the Minjiang River for water supply, transportation, and economic development.

Rainfall Situation

Fujian Province belongs to the subtropical monsoon climatic zone, where there are abundant rains in the Minjiang River basin. Generally, the rainy season starts in May and June, then again in August and September. In these months, heavy rainfall may raise the water level of this river by as much as several meters within a very short period of time.

II. Causes of Floods in Minjiang River

Causes of Flooding

1. Heavy Rainfall: Heavy rains during the rainy season account for a great contribution to floods in the Minjiang River. Torrential rains can raise the water level of the river beyond capacity very quickly, hence leading to flooding.
2. Typhoons: Very strong typhoons have always attacked Fujian Province and brought heavy rain and strong winds along with them. This might cause severe damage to the catchment area and result in flooding.
3. Topographic Condition: The Minjiang River basin is of complex landform with many mountains and valleys intertwined, so there are lots of local places where the bottom of the river is narrow, the flow is congregate, and it has poor anti-flood ability.
4. Human Activities: Improper land use without control and deforestation increase the runoff and sediment load of the river and enhance the flood hazard locally.

Flood Frequency and Severity

In the Minjiang River, relatively more frequent flooding is possible, in particular at the time of a rainy season or a typhoon's hit on this area. Its scale depends on the intensiveness of rains and strength of typhoons. Severe flooding may result in heavy losses in infrastructure, agriculture, and human life.

Impacts of Floods

1. Infrastructure Damage: It could inundate all roads, bridges, buildings, and all that sort of infrastructure, thus disrupting transportation and communication.
2. Impact on Agriculture: The floods might submerge fields, hence destroying crops and impacting agricultural production.
3. Human Dislocation: In extreme conditions of flooding, this is likely to dislocate people from their homes, hence bringing about a displacement problem that causes many hardships amongst the people.
4. Losses in Economic Activities: Floods cause losses as far as business, industries, tourism amongst others are concerned.

Lastly, it has to be mentioned that now ADCP is the more advanced and convenient measurement method of monitoring the Minjiang River while performing the forecast of floods.

III. How Do the ADCP Using Doppler Principle Work?

Acoustic Doppler Current Profiler(ADCP) work by taking advantage of the Doppler principle. The instrument projects a sound wave into the water and measures the shift in frequency of that sound wave as it is reflected back from particles in the water. The frequency shift is generated by movement of the water particles-the Doppler shift-which can then be related to the velocity of the water flow.

In the Minjiang River, ADCP current meter is deployed from a boat or fixed platform. The instrument sends out a suite of sound pulses and then listens for the returning signals. The returned signals are processed by the ADCP's on-board electronics into the water's velocity at an array of depths. Normally, the data processed would show on the instrument screen in real time and provide good data for flood prevention management.

IV. What are the applications of ADCP in Minjiang River floods?

Velocity Measurement

ADCP current profiler will be able to measure the velocity of the water flow in the Minjiang River quite accurately. In fact, this dataset is very much needed for understanding flow dynamics and developing flood risks in this river. The amount of velocity at each depth and at different parts of the river will help engineers and researchers estimate the severity of floods and take appropriate action.

Flow Measurement Applications

ADCP doppler can also be used to measure flow velocity in the determination of the flow rate of the Minjiang River. The measurement of flow is very significant in flood management. When the flow rate is determined, the authorities will be able to estimate the capacity of the river and make necessary decisions on the prevention or mitigation of floods.

Applications in Sediment Transport Research

Except for the measurement of flow and velocity, the ADCP flow meter can be used in the study of sediment transport in the Minjiang River. Quite often during floods, the quantity of sediment carried by the river is enormous, while its impact on the riverbed and ecosystem can also be very important. Measurement of sediment concentration and transport rate by ADCP will help the researcher in understanding the processes of sediment movement and developing the strategy for river management and environmental protection.

V. How can the data measured by ADCP meter be utilized to benefit from flood warning and risk management of Minjiang River?

Flood Warning:

1. Velocity and Flow Data Monitoring: ADCP profiler can continuously monitor the velocity and flow rate of the Minjiang River. With this data analyzed, early warnings are provided to the authorities over the change of status in the river. For example, if the velocity or flow rate has reached a level beyond threshold values, a flood is likely to occur.
2. Water Level Prediction and Warning: Along with other hydrological information, ADCP data can be used to predict water level. Comparing the predicted water level with historical data and flood threshold can therefore enable the authorities to issue warnings to the people who face this disaster.

Risk Management:

1. Scheduling Decision Support in Water Conservancy Projects: ADCP data may provide substantial information about flow rate and average velocity on rivers, hence helping to decide the scheduling for water conservancy projects. Using such information, it would be easy for an engineer to operate the dams and sluices to control the water level, reducing the chances of flooding.
2. Flood Disaster Evaluation and Emergency Response: In cases of a flood disaster, ADCP data will contribute to disaster assessment and assist in guiding appropriate responses. Using the depth and velocity of floodwaters measured, rescue teams would know which routes were safe enough for evacuation and other relief operations.

VI. What's needed for high-quality measurement of Minjiang River currents?

The following are needed in the carrying out of high-quality measurements of the currents in the Minjiang River:

Reliability of Equipment Materials

The equipment has to be made with reliable materials that provide for the accurate running of the measurement. One of the best kinds of metals applied in making an ADCP casing is a titanium alloy. This is because of the excellent attributes it has, which include high strength, corrosion resistance, and light weight. These properties make it suitable for use in harsh environments such as rivers and oceans.

Small Size

It should be small in size and easily deployed at every different location along the river. A small-sized ADCP would be installed on boats, buoys, or fixed platforms with no more significant interference with the flow in the river.

Light Weight

Light weight will also make transportation and deployment easy. The field personnel would find it easy to carry a lightweight ADCP and have its installation done quickly in case of emergencies.

Low Power Consumption

The essential factor for long-term monitoring is its low power consumption; lower power consumption allows ADCP to continue operating for a longer period of time without replacing frequently the batteries or connecting the power supplies.

Low Operation Cost

Equipment cost should be as low as possible for large-scale measurement. The low-priced ADCP can be installed at several places along the river and hence fully cover the river for flood prevention management.

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

Determine by Usage

1. Horizontal Cross-Section Measurement: In the case of horizontal cross-section measurement for the Minjiang River, a horizontal ADCP is recommended. This HADCP could measure the velocity and flow rate across the width of the river and provide substantial understanding about the flow characteristics in that river.
2. Vertical Cross-Section Measurement: For this purpose, the vertical ADCP will be suitable. The vertical ADCP measures the velocity and flow rate at various depths, which allows for the analysis of the vertical structure of the river flow.

Select Different Frequencies

Frequency depends on the depth of the river. A 600 kHz ADCP is sufficient for a depth of up to 70 meters, but a 300 kHz ADCP is required for depths up to 110 meters in the case of the Minjiang River.

Last but not least, it has to be mentioned that there are quite a few brands in the market for ADCP, like Teledyne RDI, Nortek, Sontek, and many more. However, for people looking for an affordable yet good-quality ADCP, one Chinese brand, China Sonar PandaADCP, is highly recommended. It uses all-titanium alloy material and enjoys an excellent price-value relationship. You can check more at https://china-sonar.com/.

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