Onset Monitoring Flow With Water Level Loggers :

One of the challenges that are currently faced by irrigation organisations and individual farms is the accurate monitoring and recording of irrigation water usage in open-channel applications. By using the HOBO Bluetooth (BLE) water level logger to record water depth, we can use the data collected to calculate flow rates and water usage in a variety of open-channel applications. A flume is used to measure flow accurately in an open ditch by forcing the flow of water into certain upstream and downstream water levels, creating a known velocity to be used in the calculation of flow rate based on the area of the flume. A weir is another measuring device that requires more upstream freeboard and often cannot be used as effectively as a flume.

Deploying of Bluetooth hobo water level data logger

To measure the water in the stilling wells, the HOBO was installed by fastening the logger to an eye-hole screw attached to the underside of the wooden shelf in each stilling well. Using Bluetooth Low Energy (BLE) technology, the data logger communicates to a mobile device via the free HOBOmobile® app, which is available for either Apple or Android products. Bluetooth communication allows one to receive the data wirelessly as well as to check the accurate real-time water level to compare to the visual staff gauge in the canal.

Site setup and data collection

After deploying, the HOBO mobile app was used to set up each site and calibrate the water level reading with an offset to match the visual reading of the water level in the canal, flume, or weir. Offset is needed to ensure that the water level recorded is the actual measurement needed for calculating of flow rate. Once connected, configured, and began logging, the measurement for the recent water level reading and battery status will be displayed. Simply tap on the name of the station to connect to the site.

To configure the logger, tap on Configure which allows you to name the site, record the GPS location (if desired), and calibrate the water level by entering the actual depth of water into the Reference Water Level. Under Logging Setup, enter the frequency of the logging interval. Once connected to the station, tap the Readout menu item as displayed on the Connected screen. Once the data file is connected to the phone or tablet, you will see a screen showing a graph of the data.

The graph shows the fluctuations in water level and allows for a quick verification that the site is recording correctly. You can easily export the data by clicking the Share icon to email the data to yourself or upload it to a cloud drive like Google Drive or Dropbox. You can export the data in an Excel-compatible file format or in a HOBO file to be opened in HOBOware on your computer.

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