Build your own automated water quality EC sensor and transmit the data over LoRa radio.
View a live example here:
https://live.innovateauckland.nz/dashboard/28a59570-c8a9-11ea-a129-5da81effbbe6?publicId=6622f130-202b-11ea-93f1-45f1eb9a31da
- Fresh water only, non-tidal. The EC 0.1 K sensor is not suited to saltwater.
- An active community group willing to periodically check on the sensor, take samples and photographs when events happen and as required
- If the sensor will also measure water height, an over water mounting location not exceeding 2.5M above normal water level, this is because the max sonar range is 3.5 Meters
- An EC sensor tether location that allows the sensor to move freely in or near the main flow. The sensor cable is around 4 metres in length. This way, water flow automatically maintains a consistent sensor location.
- A network gateway location with line of sight 1-2Km of the sensing location.
- Ability to easily access the senor unit for maintenance, cleaning and battery changes.
- Protecting the sensor in public locations. It is preferrable to locate the sensor for good measurement over avoiding theft or vandalism. Consider how to disguise or cover the senor in areas that are accessible by the public.
Please read the user guide included here to learn about the sensor installation and operation. https://github.com/aklciot/StreamECSensor/blob/master/Userguide/USER_GUIDE_WaterEC_Sensor_0.8.8.pdf
This code can be compiled on a standard Arduino GUI.
The following libraries are required:
- OneWire.h (connects data for the dallas sensor)
- DallasTemperature.h (DS18B20 digital thermometer)
- Adafruit_SleepyDog.h (Power management)
- RH_RF95.h (Radiohead driver for the Hope LoRa radio)
- Ultrasonic.h (driver for the grove ultrasonic sensor)
This sensor is designed to work with the open source LoRa telemetry network and gateway described here:
https://github.com/aklciot/TTGO-Gateway-repeater
This guide is for anyone interested in creating their own real-time environmental data sensing network. It explains how to install and use the open source water quality sensor and the data network that makes your sensor data available on the internet.
Some of the concepts in the guide are quite technical, if you’re not sure or need clarification please email us at the address below.
We recommend you have access to people familiar with connecting computer peripherals and WiFi settings.
Low cost Real-time monitoring is an amazing new capability made possible by a collection of technologies commonly referred to as the internet of things (IOT). Most monitoring techniques involve a regular visit to the monitoring location where recordings are made and recorded manually. These visits can be weeks or months apart. In real time monitoring, measurements are made automatically every few minutes and the information is immediately processed and stored on the internet. This creates an up to date, long term and detailed record.
Streams are very sensitive to weather and pollution events. These events can occur over a very short time, often after a few hours or minutes the event is over. Monthly sampling will miss most important events that occur in your stream. With real time monitoring:
Don’t miss events. Things can change fast in a stream, if you’re not there to see it you’ll miss it, the sensor watches 24/7 and creates a continuous record.
Narrow down the cause. If your stream is monitored at multiple points you can narrow down where and when an event occurred and its possible cause.
Create positive behaviours. We all change how we behave if we know we’re being watched. With the stream monitor people become aware that dumping and faults are more likely to be detected.
See the effect of restoration work. The sensor creates long term trend data. The improvements made by restoration work can be shown over time.
You can learn more about your stream and others. Combing your data with the work done by others can lead to new insights previously unavailable.
The sensor is intended to detect acute discharge events into urban waterways that would otherwise go unnoticed. It works by monitoring the water electrical conductivity (EC), temperature, and water level. Every few minutes the sensor sends data over LoRa radio to the internet where the time is recorded and the data is processed and stored. This sensor is based on low cost open source technology and as such is not a scientific grade water quality meter, however it is good enough to give meaningful information and warnings and let you know when it is time to take a closer look. To keep the cost (and maintenance) down, it does not currently monitor other stream health metrics such as dissolved oxygen (DO), pH, Phosphates, bacteria and nutrients. Some of these will be added in the future though.
EC or Electrical Conductivity of water is its ability to conduct an electric current. Salts or other chemicals that dissolve in water can break down into positively and negatively charged ions. These free ions in the water conduct electricity, so the water electrical conductivity depends on the concentration of ions.
Salinity and total dissolved solids (TDS) are used to calculate the EC of water, which helps to indicate the water’s purity.
The purer the water the lower the conductivity. To give a real-life example, distilled water is almost an insulator, but saltwater is a very efficient electrical conductor.
The system includes the ability to alert on threshold events by SMS text, email or twitter. Data can also be extracted or forwarded to other systems for modeling and trending analysis.
- Version 2.4 Published to GitHub
- Version 2.3 Added MOSFET power control and grove ultrasonic sensor
- Version 2.2 Added EC K type Calibration to loop
- Version 2.1 Added f_ec = atof(EC); to convert char to float to resolve radio send fault
- Version 2.0 Installed Atlas Scientific EC K=0.1 sensor and EZO circuit.
- Version 1.3 Installed grove ultrasonic to improve power usage.
- Version 1.2 Changed to default LoRa radio spreading factor
- Version 1.1 Corrected water temperature and EC calculation
- Version 1.0 Initial Build