How to build a low cost river monitor

How residents of Crudwell built a small Internet of Things network for live river level monitoring.

In Crudwell, several residents have setup home weather stations. The longest running is IMALME1 which is located at the south end of the village. On the day of the Storm Bert floods, IMALME1 measured 65mm of rainfall.

We think having a local weather station like IMALME1 improves flood preparedness, because all residents can easily access and see local weather data at any time of the day or night.

What type of Personal Weather Station is it?

IMALME1 is an Ecowitt weather station, and Ecowitt have a number of products including additional sensors which upload data to the cloud and can be displayed on their website or in their smartphone App.

The bit that measures rainfall is self-empting, the owner doesn’t have to check a gauge each day. The approximate cost of a weather station like this is £100.

Image 1: The IMALME1 weather station in Crudwell

How can it monitor the river level?

Ecowitt also sells additional sensors, including a laser distance sensor that would typically be used for measuring snowfall or measuring a water tank. One of Crudwell’s residents has successfully tried one out measuring the depth of the river. To do this he:

  • bought a new weather station with the optional Internet of Things (IoT) Gateway
  • bought and mounted the battery-powered laser sensor above the river, ensuring line of sight back to the weather station.

The main issue is how to mount the laser pointing straight down at the surface of the water. Some straightforward calibration is also required. The results speak for themselves, because the depth of the river is now displayed in real-time in the weather app alongside wind and rain!

Image 2: the Ecowitt laser distance sensor, pointing down at the surface of the river.

This is a huge step forward for our community. A year ago, we didn’t know the depth of the river nor the depth of the floods. Now, with a bit of ingenuity and off-the-shelf technology, we have a second weather station and know the depth of our main watercourse at any time of the day or night. We think that this complements the national EA Flood Alerts service, by giving our community more accuracy and confidence in the run-up to a possible flood.

Image 3: Screen of the app showing river depth.

How did you mount it above the river?

We currently have the laser sensor on a scaffolding pole, and are keeping a close eye on this temporary installation. We think this is a compromise, and might not to be suitable in the long term for a number of reasons. Please e-mail us if you have ideas about how to mount a downward-facing sensor without being in the river bed nor in the flow of water.

How can I see the river level?

Read our blog about the River Levels website and the Ecowitt weather app.

Where can I find more information about deploying my own river level sensor?

Click here for instructions about what to buy and how to get it working. The approximate cost is £150-300 depending on whether you have the Ecowitt weather station or not.