ADCP's Application in Flood Management of Shatt al-Arab River

1. Where is Shatt al-Arab River?

The Shatt al-Arab River is one of the more important rivers in the Middle East. It actually originates from the confluence of the Euphrates and Tigris rivers, at or very near a small city in Iraq named al-Qurnah. It then follows its course for approximately 195 kilometers through Iran and Iraq before it pours into the Persian Gulf.

This river borders the important cities like Basra in Iraq. The economy of the region depends much on the river since it facilitates transport of goods and also supplies water to agricultural and industrial activities.

The Shatt al-Arab River basin has a semi-arid climate with regard to rainfall. The rainfall is usually scanty, and the level of water in the river depends on snowmelt from mountainous areas in the catchment of the upper reaches of both the Euphrates and Tigris rivers, apart from the release of water from dams and reservoirs in the basin. Seasonal variation in the availability of water is considerable, with higher water levels normally recorded in the spring because of melting snow and during periods of heavy rainfall events.

2. What are the causes of flooding in Shatt al-Arab River?

There are many contributory factors causing floods in the Shatt al - Arab River. The most common cause is heavy rainfall in the catchments area of the Euphrates and Tigris rivers. During intense precipitation, when a vast amount of rain falls over the catchment area, the cumulative effect of water from the tributaries may provoke a sudden rise in the Shatt al - Arab River's volume.

Another reason could be the release of massive amounts of water from dams and/or reservoirs. Water release to ensure manageable water levels within upstream reservoirs or for irrigation purposes increases the level in the down-streaming river. Besides that, flat terrain in the lower parts of the river and tidal influences from the Persian Gulf also create ground for poor distribution of water and water retention, which may be the cause of the flooding.

With the importance of flood management in this area, advanced measurement techniques like the Acoustic Doppler Current Profiler have become increasingly important. This ADCP meter mode of measurement is far more efficient and accurate for flow characteristics in rivers than traditional methods.

3. How do Doppler principle-based ADCPs work?

ADCPs operate according to the Doppler principle: the instruments emit acoustic signals into the water. The frequency of these acoustic waves, while interacting with moving particles in the water-sediment grains and water molecules that are part of the current-changes. This change in frequency, the so-called Doppler shift, is linearly related to the velocity of the moving particles.

Transducers in multiple numbers are fitted on ADCPs, which emit acoustic pulses in various directions. For instance, a downward-looking ADCP profiler would be able to measure the velocity profile of the water column from the water surface down to the riverbed. Through analysis of the Doppler shifts of the reflected signals at various depths, the ADCP current profiler is able to compute the velocity of water flow at each depth. With this velocity information and knowledge of the cross-sectional area, it can then calculate the flow rate and other relevant parameters of flow.

4. What are the applications of ADCP in floods of Shatt al-Arab River?

Velocity Measurement: In the case of a flood, ADCP profiler can precisely measure the velocity of water flow at various locations and depths along Shatt al - Arab. This information is crucial for the understanding of speed and direction of the floodwaters. For example, by monitoring the velocity near critical infrastructure such as ports and oil terminals, authorities can assess the potential impact of the flood and take appropriate preventive measures.

Flow Measurement Application: ADCP flow meter provides the flow rate of the river by integrating the velocity data over the cross-sectional area of the river. In flood, this measurement helps in determining the total volume of water passing through a specific section of the river. This information is highly useful in flood forecasting and understanding the magnitude of flood.

Application of Sediment Transport Research: The sediment load in the Shatt al - Arab River is high during floods. The ADCP current meter will be able to work with backscattered acoustic signals to study the movement of sediment. Knowledge of sediment transport by flooding is of importance regarding the changes in the bed topography and consequences for navigation and also in the forecast of future flood risks due to deposition and erosion of sediments.

5. How does the data measured by ADCP contribute towards flood warning and risk management in Shatt al - Arab River?

Flood Warning

Velocity and Flow Data Monitoring: With the help of ADCP flow meter, velocity and flow data is continuously monitored to quickly identify abnormal changes in the flow of the river. When there is a sudden rise in the velocity or flow rate of the river, this signals an oncoming flood or increase in the flood situation. The data can be interfaced with flood warning systems for the issuance of timely warnings to the public and the appropriate authorities.

Water Level Prediction and Warning: Measured flow data from ADCP current profiler combined with other factors, such as the cross-sectional geometry of the river and historical records of water levels, can be used in predicting future water levels. In case the water level is predicted to exceed flood stage, early warnings can be issued to facilitate evacuation and other emergency measures. Risk Management:

Water Conservancy Project Scheduling Decision Support: The ADCP data is highly useful in making decisions with respect to the operation of water conservancy projects, which could include dams and reservoirs in the Shatt al-Arab River basin. In the case of a flood, for instance, it will consider flow data to determine an appropriate release rate from a dam that will reduce the impact of that flood further downstream.

Flood Disaster Assessment and Emergency Response: Immediately after a flood, ADCP measurements can be employed in assessing the level of flood-induced damage. This will include impacts on areas due to high-velocity flows, sediment deposition amount, and other relevant factors that would ensure accurate emergency response and recovery.

6. What is necessary for good quality Shatt al-Arab River currents measurement?

The measuring device should be made of good quality and reliable materials as the high-quality measurement of Shatt al-Arab River currents requires withstanding water corrosion and impacts from the mass of floating debris continuously in touch with the ADCP flow meter.

The equipment should also be small in size and light in weight, with low power consumption. A small and light-weight ADCP profiler is easier to install and deploy, especially in areas difficult for people to reach. Low power consumption can maintain longer-term operation without frequent battery replacement or complex power supply requirements. Besides, a device of low cost is preferred to facilitate large-scale measurement.

From the point of view of the casing material, this is an excellent choice: titanium alloy. Titanium alloy is characterized by high strength; it protects the ADCP current meter from external forces. Besides, it has great corrosion resistance, which can ensure long-term performance for this equipment in the water. Its relatively low density helps to reduce the overall weight of the device while maintaining its structural integrity.

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

The first thing to be considered while selecting the equipment for the measurement of current in Shatt al-Arab River is the purpose of use. If the focus is horizontal cross-sectional measurement, a Horizontal Acoustic Doppler Current Profiler (HADCP) is one of the suitable choices. The Horizontal Acoustic Doppler Current Profiler measures the flow velocity and other parameters across a horizontal section of the river.

If the measurement is to be taken for a vertical crosssection, then a vertical ADCP is appropriate. It can measure the velocity profile from the water surface down to the bed of the river along a vertical line.

Besides, different frequencies of ADCPs are fitting for various water depth ranges. For instance, a 600 kHz ADCP would be suitable for water depths up to 70 meters, whereas up to 110 meters, it would be worth using an ADCP current profiler with a higher frequency of 300 kHz.

There are well - known ADCP flow meter brands such as Teledyne RDI, Nortek, and Sontek. Additionally, there is a Chinese brand, China Sonar PandaADCP, which has a casing made of titanium alloy and offers good cost - performance ratio. You can visit its website (https://china-sonar.com/) for more information.

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