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River level monitoring with IoT

The ability to remote monitor river and stream levels is possible with IoT technology. IoT allows you to remotely monitor river levels in multiple locations accurately, and the data can be transmitted back wirelessly in real-time. In this blog post, we look at the different components and sensors required to monitor river levels.

Libelium Smart Cities
An ultrasonic sensor fitted to the Libelium Plug&Sense

The three most common sensors used to measure river levels with IoT are ultrasonic, radar and depth sensors. In this post, we are going to focus on the use of the ultrasonic sensor.

To provide a simple explanation, we have broken the solution into Sensors, Network and Cloud.

  • Sensors. 
    • Libelium Plug&Sense (Smart Water Xtreme or Smart Cities), with the Ultrasonic Sensor (Maxbotix MB7040). A radar sensor can be used in place of the ultrasonic sensor, with the added benefit of increased accuracy and range.
    • Milesight EM500-UDL sensors incorporate a Maxbotix sensor, 19,000mAh battery and LoRaWAN. The IP67 sensor can be rapidly deployed and are suitable for harsh environments.
  • Network. The Libelium Plug&Sense supports LoRa, 3G/4G, Sigfox, WiFi and Zigbee/XBee. For remote locations, there is also the option of using a LoRa-Satellite gateway.
  • Cloud. A range of cloud platforms is supported. The most common platforms that we work with include Microsoft Azure, AWS, and custom web applications and conventional database systems.

Sensors

Libelium Plug&Sense sensor node allows you to connect a variety of sensors (up to six).

For this scenario, we will be connecting the Maxbotix ultrasonic sensor. You may also want to include temperature, humidity and pressure, a weather station, and even a water-flow meter for river applications.

An ultrasonic sensor works by emitting sound toward an object and detecting the sound reflecting. The sensor then measures the time between each point to determine the distance between the sensor and the object being measured. The sound emitted by the sensor is at a high frequency, inaudible to the human ear, but it allows for a focused ‘beam’ (42KHz).

The Maxbotix I2CXL can detect the distance of an object at a range of up to 10m, with a 1cm granularity.

How do I power the sensor?

The Libelium Plug&Sense includes a built-in 6000mA-H battery and support for an external solar panel. The use of batteries and renewables allows the sensor nodes to be deployed in remote environments.

Network

Smart Water
The Libelium Plug & Sense Smart Water has dozens of sensors to detect chemicals, turbidity and the presence of metals.

Wireless technologies such as LoRa, WiFi, 3G/4G and Sigfox are supported by the Libelium Plug & Sense.  The flexible range of options allows you to choose the right wireless technology to send data back to your systems or application servers. For very remote locations, a technology such as LoRa (supported by the node) and a LoRa-Satellite gateway allows water monitoring from any location in the world!

Cloud

Data from the sensors (once transmitted) needs to be processed and stored. The use of cloud platforms such as Microsoft Azure is perfect for IoT. However, the platform supports sending data to Azure, AWS and familiar application/database servers. Once in the cloud, you can develop additional functionality such as alerting and notifications (i.e. if the river level exceeds a given level or there is an upwards/downwards trend of significance).

Remote water level monitoring solution

The Sensor node is attached to a river structure such as a bridge or installed on a pole adjacent to the river that needs to be monitored. The Ultrasonic sensor is connected to the node and installed above the body of water. At this point, the sensor will be measuring the distance between itself and the body of water.

If you know the depth of the river at this point – any increase or decrease in the sensor value (i.e., 25cm) would indicate a reduction in water levels, while any increase (+15cm) would suggest an increase in water levels.

Ultrasonic Probe for River Monitoring
The node is installed on the bridge with the ultra-sonic sensor pointing towards the river. The sensors measure the distance between the sensor and the river to an accuracy of 1cm. These measurements are then used to assess the height of the river. The sensors work at a range of up to 7.6m (10m in the extended version). Data is then transmitted using LoRa/4G/3G/WiFi/Sigfox.

Sampling Intervals

The sensor node (Libelium Plug&Sense) will then transmit this measurement back to the cloud platform. Measurement intervals can be as little as a few seconds, but a practical range would be every 15 minutes. For higher-risk rivers or where pre-emptive flood detection is needed – you may want to measure levels every minute.

The only disadvantage of more aggressive sampling intervals is the battery life of the sensor node.  More measurements mean more power consumption – an important consideration if the sensor node is being powered from the battery and solar.

Alert and notifications

Once the data is in a cloud platform, applications can be developed that do the following:

  • Visualise the water-level data on a dashboard.
  • Send text messages when water levels exceed a given value.
  • Generate alerts (text or e-mail) when the water levels increase at a given gradient.
  • Send messages via Slack, Microsoft Teams or WhatsApp when thresholds are exceeded.
  • Combine reports with weather data to understand the correlation and risk factors associated with water levels and weather.

Early warning flood monitoring

It is easy to see how remote water level monitoring can also be used in flood monitoring and flood protection scenarios:

  • Sensors can be deployed throughout the Long Profile of a river or river network (i.e. lower, middle and upper courses).
  • IoT sensors can monitor levels of rivers, lakes and streams throughout the network.
  • River sensors can be combined with weather stations to monitor rainfall.
  • The rate at which river levels increase throughout the network can be monitored in real-time.

Flow-rate monitoring

It is possible to monitor river velocity and flow using radar planar microwave technology, with doppler radar technology.

River flow / streamflow monitoring

When level sensors are combined with flow sensors, it is possible to calculate the volume of water flowing down a river. Monitoring river flow is covered in the following article.

Digital Twins – Rivers

Digital Twins can use the data arising from sensors to create detailed models of rivers systems. IoT technology can be the foundation of a Digital Twin solution when coupled with data analysis, machine learning, artificial intelligence (AI) and visualisation tools.

Digital Twins can incorporate additional sensors into their modelling:

  • Soil moisture sensors at different depths allow you to monitor the status of the water table.
  • Weather stations allow accurate weather data analysis such as rainfall, pressure, temperature, wind and solar radiation.
  • External data sources such as topographic and terrain data.

Data visualisation and reporting

The data collected from IoT sensors can naturally be used for detailed data analysis and reporting. Depending on the choice of platform, data can be brought into common database platforms such as Microsoft SQL Server or MySQL. The data can then be visualised using tools such as Power BI, Tableau and Zoho Analytics. For more simple use-cases, data can be downloaded in CSV or Excel format.

Sensor summary

  • River level sensor – Ultrasonic, radar and pressure sensors.
  • Weather stations – Rainfall, wind, solar radiation, pressure and temperature.
  • Turbidity, ORP, Dissolved Oxygen
  • Soil moisture sensors – available at different depths
  • River flow and velocity sensors – Radar/Doppler sensors

What else can I monitor?

In addition to water levels, we can monitor a wide range of parameters associated with water, such as pH, ORP, Dissolved Oxygen, BOD/COD and conductivity. To learn more, review the following blog posts:

Conclusion

IoT is an excellent solution for remote monitoring river levels in a high accuracy manner. Ultrasonic sensors and the Libelium Plug&Sense offers a field-proven and reliable solution that supports a range of communications technologies.

More information

If you would like to learn more about our products and services, request pricing, or discuss a project requirement - you can MTG using the details below. Alternatively, you can e-mail sales@mtg.im for more information.

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Joe Hughes is the CEO of Manx Technology Group. Joe has a background in software development, information security, networks, datacentres and enterprise IT.
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