ADCP Application in the Tigris River Flood Management

1. Where is the Tigris River?

The Tigris River is one of the two great rivers constituting Mesopotamia, the other being Euphrates. Originating from the Taurus Mountains in eastern Turkey, the river runs through Syria and Iraq.

Geographically, it cuts across several types of terrain. In its upper reaches in Turkey, it passes through mountainous regions with steep slopes and rapid water flow. As it enters the plains of Iraq, it slows down and meanders through agricultural areas and ancient cities such as Baghdad. Water from the river is crucial in arid and semi-arid areas where it passes through; the water for irrigation supports extensive agricultural activities, such as wheat, barely, and dates.

In terms of rainfall, the Tigris River Basin experiences a Mediterranean climate in its upper reaches and a more arid climate in the lower parts. The upper regions receive more rainfall during the winter months, which contributes to the river's flow. Snowmelt from the mountains also adds to the water volume. In the lower reaches, rainfall is less abundant, and the river's flow is maintained by the water coming from upstream and by groundwater contributions.

2. What are the causes of flooding in Tigris River?

Heavy Rainfall and Snowmelt: are the most critical conditions whereby heavy rainfall in the catchment area, particularly in the winter months, causes an extraordinary rise in the water volume of the Tigris River; similarly, snow melting on the Taurus Mountains in spring may send a great quantity of water downstream. As these factors combine together, such a kind of water inflow may exceed the usual carrying capacity of the river.

Tributary Inflows: There are many tributaries into the Tigris River. When these tributaries have high levels due to excessive rain or snow melt-off, they contribute huge amounts to the main channel of the river. If the sum of tributary and main channel flows is more than can be accommodated by its channel and floodplains, floods result.

Relief and Drainage: The course of the river includes areas with relatively flat floodplains and some narrow valleys. The flat floodplains can slow down the flow of water, allowing it to spread out and flood adjacent areas. In the narrow valleys, water can rise quickly during heavy inflows. Poor drainage in some areas can also exacerbate the flood situation.

Land Use Changes: Human activities that involve the expansion of agriculture and urban development affect the hydrologic cycle. For instance, dam and canal constructions for irrigation alter the hydrologic natural flow. Also, deforestation and conversion of natural grasslands to farmland reduce the infiltration capability of the land, leading to a greater surface runoff and causing flood disasters. In this context, the Acoustic Doppler Current Profiler (ADCP) offers a more advanced and efficient means of measurement for flood - related data compared to traditional methods.

3. How do ADCPs using the Doppler principle work?

ADCPs work on the principle of Doppler. They send acoustic signals into the water. These acoustic waves meet the moving particles in the water-sediment, debris, or water parcels with different velocities-and the frequency of the reflected signals, compared to the emitted signals, changes due to the Doppler effect.

These frequency shifts are measured by the ADCP meter, which then calculates the velocity of the water at different depths using the known speed of sound in water and the angles of the emitted and received signals. In an ADCP flow meter, multiple transducers are arranged to measure velocity components in various directions. Integrating these velocity measurements over different depths and cross-sectional areas of the river gives the flow rate and other important hydrological parameters.

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

Velocity Measurement: The ADCP current profiler can measure the velocity of water flow in the Tigris River at various locations and depths quite precisely. This information is of extreme relevance during flood events for depicting the dynamics of the flood. It indicates locations where the flow might be rapid enough to cause risks to riverbanks, bridges, and other infrastructures. It also allows for the monitoring of changes that the flow velocity experiences through time as the flood develops.

Flow Rate Measurement Application: Combining the velocity measured and the cross-sectional area of the river, ADCP current meter will compute the flow rate. It's critical to know what volume of water will pass in various sections when the river floods. This is because the potential to forecast a flood peak and its effects on downstream regions enables flood management strategies.

Sediment Transport Research: A flood in the Tigris River may carry a heavy load of sediment. Using ADCP profiler, one can conduct an analysis of sediment transport by identifying echoes of acoustic signals caused by the sediment particles. Such information gives valuable insight into how the flood influences bed evolution, sediment deposition, and erosion processes in the riverbed, which is relevant to maintaining stability in the river channel and the surrounding ecosystem.

5. How can the data measured by ADCP be utilized for flood warning and risk management of Tigris River?

Flood Warning

Velocity and Flow Rate Data Monitoring: ADCP current meter continuously monitors the data on velocity and flow rate. It permits, therefore, the early detection of abnormal increases in these parameters. Approaching or surpassing specific critical values of the flow rate serves as an indication of an impending flood peak. This will enable timely warnings to the communities and relevant authorities along the river.

Water Level Prediction and Warning: With models, the flow rate and velocity data measured can be combined with historical records of water level to predict future water level fluctuations. This gives good warnings in advance about the area which is likely to be flooded along with the height of the floodwaters, allowing them to take necessary precautions.

Risk Management

Water Conservancy Project Scheduling Decision: The ADCP data might help in the decision of planning the operation of water conservancy projects, like dams or reservoirs, on either side of the Tigris. For instance, the best and proper time and the proper amount of water release required from the reservoir to retain the flood effects at the downstream sites can be calculated with better accuracy.

Flood Disaster Assessment and Emergency Response: In the aftermath of a flood, ADCP-measured data can be used to assess the severity of the flood, such as the extent of inundated areas and the flow characteristics during the flood. This information guides emergency response efforts, including the allocation of relief resources and the planning of post-flood recovery work.

6. What's Required for High-Quality Measurement of the Currents in the Tigris River?

The equipment required for high-quality measurement in the currents of the Tigris River should have appropriate material. The casing must be such that it could bear all the harsh conditions of the river, like impacts of floating debris, corrosion of water of different chemical composition, and the wide range of temperatures in the region.

The size of the equipment should be small enough to be easily installed and deployed at different locations in the river. A lightweight design is also beneficial for ease of transportation and installation. Low power consumption is necessary to ensure continuous operation over long periods without the need for frequent battery replacements or high-energy power sources. Cost-effectiveness is another important factor to enable large-scale deployment for comprehensive monitoring.

The casing of ADCP profiler is best made from titanium alloy. It has several outstanding advantages: outstanding corrosion resistance, which is crucial for sustaining long-term exposure to river water; a high strength-to-weight ratio, which provides enough strength while keeping the weight of the equipment at a reasonable level. In addition, this durable material will guarantee stable performance under the diverse environmental conditions of the Tigris River Basin.

7. How to Choose the Right Equipment for Current Measurement?

While selecting appropriate equipment to measure current in the Tigris River, there are some factors to be considered.

First, it depends on the purpose of use, during which, if horizontal cross-section measurement is the concern, then the Horizontal ADCP-HADCP would be quite suitable as it can measure with a good deal of accuracy the flow velocity and other parameters in the horizontal direction across the river section. The Vertical ADCP is more appropriate for vertical cross-section measurement, since it can provide detailed velocity profiles along the vertical axis of the river.

Second, different frequencies should be chosen according to the actual water depth. For the water depth within 70 meters, an ADCP of 600 kHz can give accurate measurement results. While for the water depth up to 110 meters, the ADCP current meter at a frequency of 300 kHz is more effective since it has a greater depth penetration with reliable data.

There are various ADCP current profiler brands available in the market, such as Teledyne RDI, Nortek, and Sontek. However, it is worth highlighting a high-quality and cost-effective Chinese ADCP brand-China Sonar PandaADCP. It is made of all - titanium alloy material, ensuring excellent performance and durability. You can find more information on its website: (https://china-sonar.com/)

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