ADCP in Flood Prevention Management of Aruwimi River

I. Where does Aruwimi River lie?

Natural and Geographic Features 

The Aruwimi River is located in the center of Africa. The river flows in a northeastern direction and drains into the Congo River. Meandering through the heavy rainforest and savannah regions of the Congo Basin, it takes its course. All in all, the nature of the Aruwimi River is wide and slow-flowing, with a rich and diverse aquatic ecosystem. The water is often turbid since the river carries much sediment from its surroundings.

Cities and Settlements Along the River 

The Aruwimi River has various small indigenous communities and trading posts along its course. It supplies most of these communities with fish, transport, and water. As a result, the river becomes an important lifeline in the transportation of people and goods through the region.

Rainfall Situation 

The high amount of precipitation throughout the year points to a tropical climate in Aruwimi River Basin. It is more or less evenly distributed, but certain periods may peak therefore giving rise to water levels. The high rainfall in the catchment due to the ITCZ and rainforest, which also contributes to the general water cycle through evapotranspiration.

II.What are causes of flooding in Aruwimi River?

Causes of Floods

1. Heavy Rainfall: The most striking cause of the floods in the Aruwimi River is intense and continuous rainfall. Due to heavy rain, much water falls over this big river basin and easily fills up the river and its tributaries. At times when there is heavy and prolonged rain, the soil of the rainforest, with a high waterholding capacity, is brought to a saturated state and allows more runoff into the river.
2. Tributary Input: Many tributaries supply the Aruwimi River, and most of them drain portions of the forest and savannah. Where such local rainfall makes their water levels high, this causes a contribution to the volume of water carried by the main river, thereby raising the chance of flooding.
3. Geographic Features: The flat floodplains and meandering nature of the river contribute to the proneness of flooding. During periods of high water, the river may break over its natural levees and water may spread out onto the surrounding low-lying areas.

Frequency and Scale of Floods 

With such high rainfall and of that character, flooding of the Aruwimi River is just about normal. Depending on the intensity of the rainfall, frequency may vary with different years. These floods can be anything in scale, from the minimum rise of the level to inundate the riverbanks and adjacent forests to major flooding covering hundreds of square kilometers of floodplains and leading to disruption in the lives of the local communities. 

Impact of Floods

1. Infrastructure Damage: The floods have a capacity to damage the simple infrastructures such as wooden bridges, canoe ports, and water-supply systems in the local communities. This might interfere with transportation and supply of clean water.
2. Impact on Livelihoods: The local communities relying on fishing and small-scale agriculture are seriously affected. The floodwaters can wash away fishing gear and inundate the entire agricultural fields. This leads to food shortage.
3. Displacement of People: In extreme flooding, people in these lowland communities may have to be transferred to higher grounds. This causes crowding and shortages in temporary shelters.

ADCP current meter provides a more advanced and effective method of measuring and understanding the flow of the Aruwimi River, which is important for flood prevention and management.

III. How Do ADCPs Using the Doppler Principle Work? 

The basis of operation by Acoustic Doppler Current Profiler(ADCP) follows the principle of the Doppler. First, they emit acoustic pulses, that is, sound waves, into the water. Owing to the movement of the water particles, these sound waves are reflected back to the ADCP current profiler. Due to the Doppler effect, the frequency of the reflected sound waves has now changed. The change in frequency is directly related to the velocity of the water particles.

In the case of the Aruwimi River, ADCP doppler can be deployed by attaching them to boats, floating platforms, or fixed structures placed along riverbanks. The instrument sends a train of sound pulses at known frequency into the water. The internal electronics of the ADCP flow meter process the received and reflected signals. The velocity of the water column at various depth levels is determined by computing the frequency shift of the reflected signals from respective depths. With this, data can be processed and shown in real time, which gives extremely useful information on the water flow in the Aruwimi River.

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

Velocity Measurement Basically

ADCP meter has been fundamental in providing flow velocity of the moving water mass of the Aruwimi River. By finding the velocity at different depths and locations, it helps in understanding the flow dynamics and predictive capability on how floodwaters may spread and move. All this information is crucial in the evaluation of the likelihood of floods in areas around and planning evacuation and relief accordingly. 

Applications of Flow Measurement 

The ADCP profiler flow rate measurement of the Aruwimi River is very important in terms of flood control. The data can be useful in understanding the overall water balance and flood peak prediction; this information may be used to manage the water levels through the operation of whatever flood-control structures are available, although there may be few in this region, such as simple weirs or dams. 

Applications in Sediment Transport Research 

Large sediment loads are transported during flooding in the Aruwimi River. Doppler current profiler can measure the concentration and the amount of sediment transported. Knowledge of sediment movements is important to help maintain healthy rivers and their ecosystems. Data obtained will enable the forecasting of where sedimentation is going to occur, essential for terre-fixe construction, and understand the long-term development of the river and its regions nearby.

V. How can data measured by ADCP contribute to flood warning and risk management of the Aruwimi River?

Flood Warning

1. Monitoring Flow Velocity/Discharge: ADCP continuously monitors the water current and the actual flow of the Aruwimi River. A threshold can be set for those parameters and send warnings in case of an abnormal increase in water flow to the local authorities or leaders within the community or regional agencies. For example, a sudden rise in velocity or flow rate depicts an imminent flood. It is an early warning system necessary for the timely evacuation of the population in flood-hazardous areas and to undertake elementary actions for protection against floods.
2. Water Level Prediction and Warning: Integration of ADCP data with all hydrological data at that reach, including rainfall measurements and the water storage levels in local ponds or small reservoirs (if any), can result in much better forecasts of the water level. Comparing these forecasted levels with the historical flood water levels will enable timely warnings for the local communities.

Risk Management

1. 1. Decision Support for Water Conservancy Project Scheduling: Acoustic doppler velocity meter data provides valuable input to the operation and scheduling of any water conservancy projects in Aruwimi River. The flow rate and velocity data, for instance, can be supportive in determining the best release of water from small dams or water-storage structures to meet flood controls and water supply needs. It also helps in designing and maintaining simple flood-protection structures such as levees or flood-barriers.
2. Flood Disaster Assessment and Emergency Response: The ADCP data are very useful in disaster assessment immediately after a flood event. It analyzes the post-flood patterns of velocity and water depth in order to help emergency responders understand which areas have suffered the most; this helps them in planning rescue operations, distribution of relief supplies, and in long-term recovery and reconstruction operations.

VI. What is required to give high-intensity measurement of the Aruwimi River Currents?

Reliability of Equipment Materials 

It also needs to be made of reliable materials for the correct measurement of the Aruwimi River currents. The casing of the ADCP is preferred to be made of titanium alloy material. This is because titanium alloy has excellent strength that resists pressure and physical forces from the Aruwimi River. Moreover, it doesn't corrode easily, hence assurance of the long-term durability of the equipment from water and sediment. 

Small in Size 

A small-sized ADCP is of great importance when being deployed in the Aruwimi River. The sensor device will be installed on various platforms such as small boats, buoys, or on riverbank monitoring stations with minimal obstruction of the river flow, therefore allowing a wider range of placement possibility to obtain full current measurements. 

Light Weight 

Light - weight ADCPs are easier to transport and mount at most of the remote areas along the Aruwimi River. Field technicians, if available, can take it to any location and, within no time, set up for measurement. It's quite advantageous in emergency flood-monitoring situations. 

Low Power Consumption 

The instruments that can facilitate the running of the monitoring of the Aruwimi River over long stretches of time should have low power consumption, such as ADCPs. It is very desirable, therefore, that equipment could be used which can run for long periods without constant battery replacements or interruptions in power supply. 

Low Cost 

We would like the ADCP equipment costs to be as low as possible to make large-scale measurement along the Aruwimi River possible. That way, several units at different points of the river could be put in place to get an overall view of its currents and flood risks.

VII. Comment Choisir le Materiel Appropriate de Mesure de Courant?

Determiner par Usage

1. Horizontal Cross - Section Measurement: HADCP represents the preferable option when it comes to the horizontal cross-section measurement of the Aruwimi River. The HADCP can measure the velocity and flow rate across the river's width, allowing a full picture of the flow characteristics of the river at any given cross-section. This becomes important in knowing how the water spreads out across the river and for flood-plain management.
2. Vertical Cross - Section Measurement: In terms of vertical cross-section measurement, a vertical ADCP will serve better. It can give the velocity and flow rate at variable depth. This thus allows analysis of the vertical structure of river flow. This becomes important in understanding the stratification of water and sediment movement.

Use Different Frequencies 

Frequency depends on the depth of the Aruwimi River. Usually, a 600 kHz ADCP works for depths up to 70 meters. If sections are deeper, up to 110 meters, then 300 kHz is the best option.

Finally, there are several well - known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for cost - effective and high - quality ADCPs, the Chinese brand China Sonar PandaADCP is highly recommended. It features an all - titanium alloy material construction and offers excellent value for money. You can visit (https://china-sonar.com/) for more information.

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