How to measure water current of Hadejia River?

1. Where is Hadejia River?

The Hadejia River is one of the most well-known rivers in the northern part of Nigeria. It flows as an important component of the system of the Hadejia-Jama'are River. The river runs its course through the varying landscapes from Savannah to agricultural plains.

As such, it crosses a large number of villages and towns along the way. These communities have a long-standing relationship with the river. The Hadejia River is a source of water for domestic use, such as drinking, cooking, and washing. It also plays an important role in local agriculture. Farmers depend on its waters for irrigation, being able to grow a wide range of crops, including millet, sorghum, and vegetables. These riverbanks are mostly lined with vegetation, with almost every species of bird-one thinks of herons and kingfishers in particular-finding a home and good fishing in its waters, and mammals such as muskrats making their homes among the bushes and reeds.

2. What is the flow rate of the Hadejia river?

The flow rate of the Hadejia River is quite irregular, changing from season to season. During the wet season, normally around [approximate months of the wet season in the region], there is an influx of much water as a result of heavy rains experienced in the catchment area. The flow can become rather robust with high velocities of water and relatively high discharge rates. The high-flow discharge can be in the range of [estimated high-flow discharge in cubic meters per second].

In the dry season, the situation is very different. The flow rate slows down considerably as the supply of water decreases. It may become narrower and shallower. The average flow velocity during the dry season may vary from [provide an estimated range, e.g., 0.1 - 0.5 meters per second], and the discharge can be as low as [estimated low-flow discharge in cubic meters per second]. Such variations in flow rate have a far-reaching impact on the local ecosystems and the economic activities of the communities dependent on the river.

3. How to measure water current of Hadejia River?

There are many ways of measuring the water current of the Hadejia River:

Velocimeter method: This is the traditional method, in which mechanical or electrical velocimeters are used. These instruments are placed at different depths and locations along the river. By directly measuring the speed of the water flow at these specific points, a basic understanding of the current can be obtained. However, this approach requires a lot of manual work and time, especially when trying to map out the current profile across different parts of the river.

Acoustic Doppler Current Profiler (ADCP) method: The ADCP current meter is one of the most efficient and advanced techniques. It emits an acoustic signal into the water column and determines the frequency shift of the reflected wave-a process called the Doppler shift-to calculate the water's velocity at different depths of flow. The ADCP gives a much more comprehensive picture of the flow conditions of the river in less time compared with the velocimeter method.

Buoy method: Under this method, the Hadejia River surface will be dotted with buoys carrying sensors or tracking devices. From the rate of drift of the buoys with time, the surface current speed and direction can approximately be estimated. The shortcoming is that this mainly deals with the surface flow and might not be entirely representative of conditions at greater depths.

Among these methods, the ADCP flow meter currently enjoys a reputation as a more advanced and handy method of measurement of water current of the Hadejia River because of its capability to give very detailed, multi-depth data with relatively less effort.

4. How do Doppler principle-based ADCPs work?

ADCPs operate according to the Doppler principle. They emit acoustic pulses of a certain frequency into the water. When these sound waves interact with moving particles in the water, like sediment particles or small organisms, the frequency of the reflected waves changes. This change is known as the Doppler shift.

When the particles are moving towards the ADCP meter, the reflected frequency is higher than the emitted one; when they are moving away, it is lower. By precisely measuring this frequency shift and taking into account the angle at which the acoustic signals were emitted and received, the ADCP meter can calculate the velocity of the water at different depths. Multiple transducers on an ADCP profiler are usually mounted at different orientations to measure flow velocity in various directions both in horizontal and vertical components. A detailed profile can therefore be made of the water current within the river.

5. What's needed for high-quality measurement of Hadejia river currents?

The equipment for high-quality measurement of the Hadejia River currents has to possess certain qualities. First, the materials used in the making of the measuring devices have to be reliable. The equipment has to be able to put up with the often-harsh conditions of the river environment. This includes being able to handle potential impacts from floating debris, as well as variations in water temperature and quality.

Secondly, it needs to be of smaller size, low power consumption, and low in weight. A small size can allow for the implementation of easy deployment and retrieval; this is most helpful when in a region whereby the river is somewhat challenging due to the topography and insufficiency of infrastructure in approach routes. Low power consumption can enable the operation over an extended period without replacement or use of external power supplies.

Another important consideration is cost for large-scale measurement. In ADCPs, titanium alloy is a very good choice for the casing material. There are many advantages of a titanium alloy. It has excellent corrosion resistance and thus can withstand long-term exposure to the river water without significant damage. Strong, resilient to mechanical stresses like those due to water currents and impacts, by accidents or otherwise. It is pretty lightweight for a lot of metals, hence being applied to equipment used in water current measurement.

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

To start choosing the right equipment to measure the current of the Hadejia River, consider the following:. The Horizontal ADCP would work well for a horizontal cross-section of flow in a river. That is because its design covers the flow features in a horizontal plane well. Since the vertical profile of flow might be needed down a specific vertical line along different depth levels, for this purpose, one would use a Vertical ADCP.

Different frequencies of ADCPs are suitable for different water depths. For instance, an ADCP with a frequency of 600 kHz is well-suited for water depths within 70 meters. This would make clear and precise measurements in the relatively shallow parts of the Hadejia River. Meanwhile, an ADCP with a frequency of 300 kHz is more appropriate for water depths up to 110 meters, enabling effective measurement in the deeper sections of the river.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, for a cost-effective yet high-quality option, the China Sonar PandaADCP is worth considering. It is made of all-titanium alloy material, ensuring its durability and reliability and offering an excellent cost-performance ratio. You can find out more about it on its official website: https://china-sonar.com/.

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