Water sampling

The monitoring system has been designed in close collaboration with Melbourne Water within the Melbourne Waterway Research-Practice Partnership, and more especially the B2 project of the partnership untitled Major sources and fate of sediments in streams, wetlands, estuaries and bays to inform management opportunities.

The set-up installed in Quirks, Victoria is an illustration of the monitoring system installed on the different sites.

Quirks upstream monitoring site. The system monitors the water level, the flow and trigger volume-based samples.

Monitoring objectives

For each site, the objective is to monitor in real-time (6 minutes time step) the water level in the stream, the flow (using a weir), and trigger volume-based samples when  a specific water level is reached.

Quirks flow measurement weir

The system is also sending the data in real-time, including other parameters such as the cumulated rainfall (since 9 am) provide using the closest Melbourne Water weather station, the GSM signal reception.

Public platform

All the data is accessible in real-time on the Mind4Stormwater online platform. Anyone can visualise one or several parameters simultaneously and download the data.

Quirks upstream parameters from the Mind4Stormwater online platform.

Monitoring system

The system combine an expensive, accurate (1 mm) and reliable sensor, the Pressure Level Sensor (PLS) from OTT, the Sigma 900 MAX Portable Sampler from HACH, and a low-cost system for data logging, saving and communication. The system is powered by a 12V battery and connected to a solar panel to be energy-independant.

Quirks monitoring system schematics: OTT pressure level sensor + float switch + HACH portable sampler + MKR 1400 GSM + SD shield + relay shield

The low-cost system consist mainly in a MKR 1400 GSM, a MKR SD shield and a MKR relay shield. The GSM board allow sending data in real-time to a google spreadsheet and then the online platform. The board can also receive sms, allowing powerful interaction (see below).

Two-way communication with the monitoring system: data sent in real-time to the google spreadsheet and remote control of the system using SMS.

The google spreadsheet is used as an expert platform:

  • Access to the full data,
  • Quickly see when the last data arrived,
  • Receive emails when on predefined conditions:
    • Water level reached,
    • Low-battery voltage,
    • Start of a sampling campaign,
    • No data received for a specified amount of time

The interaction with the board allows:

  • To change any monitoring parameter (period, offsets, publishing frequency, power saving mode, log)
  • To test the system (start a measure, a sample)
  • To change sampling triggers (water level and volume)

Sampling campaign

Based on predefined trigger, the system will autonomously start the sample. The figure below present an illustration of a sampling campaign for both the upstream and downstream of Quirks.

Quirks sampling campaign. The campaign is started based on a predefined level, every 100 m3 of water triggers a sample and the campaign stops when a predefined (low) water level is reached.

The predefined water levels and the trigger volumes can be changed remotely (by sms) at any time. The system can be configured not to sample during the Friday or Saturday if needed.

On-site intervention

Initially, a blinking code has been developed to allow the operator to know what part of the code is running, as shown below.

Quirks monitoring site blinking system

This technique has however proven its limitation, and the next development has been to add an OLED screen in order to better inform the operator: code running and parameter measured.

Picture of the system, the OLED screen is the black element in the middle of the picture

The OLED is OFF by default to save power and can be activated for 15mn by SMS.

Arduino code

The code is accessible on Github:
Using a MKR 1400 GSM board