Measurement of Water Current of the Murat River

1. Location and Importance of the Murat River

The Murat River flows through the eastern part of Turkey and represents one of the head tributaries of the Euphrates River. Getting its sources from the Ağrı highlands, it flows over mountainous terrain and passes through many valleys.

The river is important in the local ecosystem, providing water for various flora and fauna. There is a variety of wildlife found within the surrounding areas, with fish species adapted to the conditions of the river. Agricultural lands line its banks, where farmers depend on the water of the river for irrigation. The river is also important in the local communities for domestic water.

2. Flow Rate Characteristics of the Murat River

The flow rate of the Murat River has a very relevant seasonality. During the spring, with the melting of snows in the upstream highlands, the river shows an incredible increase in flow, increased water level, and thus strong current. Such times are crucial for the transportation of much sediments and nutrients further downstream, enriching the floodplains and the soils in the adjacent areas.

In summer and autumn, it stabilizes to a certain extent, but still depends on rainfall in the catchment area. During winter, the flow rate may decrease but never usually stops completely; it normally maintains a base flow arising from the groundwater sources and storage in the upstream areas. While, average flow rates depend on the amount of snowfall in the mountainous upstream, topography in terms of the river basin geometry that decides the collection of water and drainage, as well as consumption by the local community, mainly agriculture and household purposes.

3. Methods to Measure the Water Current

Velocity Meter Method

The traditional method uses mechanical or electronic velocity meters. These meters are placed in the water at certain points for measuring the speed of running water. To obtain a complete profile of the current, several deployments at various locations and depths are required. This is quite time-consuming. This technique also may not provide a continuous profile of the current throughout the water column.

Acoustic Doppler Current Profiler (ADCP) Method

The Acoustic Doppler Current Profiler (ADCP) method is more advanced and efficient. It uses sound waves to measure the velocity of water at different depths simultaneously. It can create a detailed profile of the current from the surface to the riverbed by emitting acoustic signals and analyzing the Doppler shift of the reflected signals. This enables the measurement of the water current across different sections of the river with greater accuracy and completeness.

Buoy Method

The buoys are located in the river and their displacements are measured after sometime. The displacement of buoys due to the water current gives an indication of the speed and direction of flow.

However, this method has several drawbacks. It may not give correct velocity at various depths and may be interfered with by external factors such as wind and waves, which affect the movement of the buoys.

Among these methods, the ADCP method is generally the more advanced and convenient option for measuring the water current of the Murat River.

4. Working Principle of ADCPs Based on the Doppler Effect

ADCPs work on the principle of the Doppler effect. An acoustic signal is transmitted from the ADCP current meter transducer into the water and interacts with the moving particles of water. Due to the flow of water, the frequency of the reflected sound waves changes as a result of the interaction back to the transducer-a phenomenon labeled as Doppler shift.

If the water is moving towards the transducer, then the frequency of the reflected waves will be higher than the emitted frequency. If the water is moving away from the transducer, then the frequency will be lower. By precisely measuring this frequency shift at multiple angles and depths, the ADCP current profiler calculates the velocity of the water in different directions and at different levels within the water column. The high resolution provided by the velocity distribution enables it to build an image-like profile of the water current, carrying information on speeds and directions of flow, both from the surface to the riverbed.

5. Requirements for High-Quality Current Measurement

The measuring device for high-quality measurement of currents in the Murat River should have the following qualifications.

Construction materials for the equipment should be reliable to allow for real and accurate measurement. The size should be small for easy deployment and retrieval in the river, especially for areas with difficult access.

It is also supposed to be lightweight in nature, which simplifies the installation process as well as reduces much effort required during handling. The power consumption has to be low so that the equipment can operate for a long period without any frequent battery replacements or any complex power supply setup. Cost-effectiveness is another major factor for the reason that it would allow wider usage and larger-scale measurement campaigns.

In this context, titanium alloy will be a great choice for the casing of the ADCP profiler. The advantages of titanium alloy are many. It is highly resistant to corrosion, and this is important because the equipment is always in contact with water that may have different minerals, sediments, and pollutants. It also has a good strength-to-weight ratio, enabling a durable and lightweight casing. In addition, it will be able to resist the mechanical stresses occurring during deployment and operation in the flowing water of the Murat River.

6. How to Select the Right Equipment for Current Measurement

When choosing the right equipment for measuring the current of the Murat River, two main factors should be considered.

Purpose-based Selection: For horizontal cross-section measurement, the Horizontal ADCP (HADCP) is the suitable option. It is designed to measure the flow velocities across a horizontal plane in the river with high accuracy, which is useful for understanding the lateral distribution of the current. In the case of vertical cross-section measurement, the Vertical ADCP is more appropriate since it focuses on profiling the current from the surface to the bottom along a vertical line in the water column.

Depth-related Consideration: Different frequencies of ADCPs are suitable for different water depths. For example, the 600 kHz frequency class ADCP is suitable for water depths within 70 m. Thus, it can provide current measurements relatively accurately in the shallower parts of the Murat River. An ADCP meter of 300 kHz is more suited for water as deep as 110 meters and would be appropriate in sections of the river with greater depths.

There are well-known brands of ADCPs such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost-effective option with good quality, the China Sonar PandaADCP is highly recommended. It is made of all-titanium alloy material and offers an incredible price-performance ratio. You can find out more about it on its website: https://china-sonar.com/.

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