Water Quality and Flood Monitoring Networks

Environmental monitoring is one of the most compelling applications for LoRa mesh networks: sensors can be deployed in remote, power-limited locations that are difficult or expensive to reach with traditional wired or cellular connectivity.

Water Quality Monitoring

Mesh-connected water quality sensors provide real-time data for rivers, lakes, reservoirs, and municipal water systems:

Parameters to Monitor

• pH — Atlas Scientific EZO pH circuit + probe (~$80). pH outside 6.5-8.5 indicates contamination risk.
• Turbidity — Measures water clarity; spikes indicate sediment runoff or contamination events
• Dissolved Oxygen — Critical for aquatic life; low DO indicates algal bloom or organic pollution
• Conductivity/TDS — Total dissolved solids; elevated levels indicate industrial runoff or saltwater intrusion
• Water temperature — DS18B20 waterproof probe (~$5); temperature affects biological and chemical processes
• Water level — Ultrasonic or pressure transducer sensor; critical for flood warning systems

Hardware Architecture

A complete water quality node:

• RAK4631 base (ultra-low power nRF52840)
• Atlas Scientific EZO carrier board (I2C) for multi-parameter sensing
• DS18B20 waterproof temperature probe
• IP68 fiberglass enclosure with cable glands for sensor probes
• 10W solar panel + 10Ah LiFePO4 battery (year-round autonomous operation)
• Transmit interval: 15-30 minutes (low duty cycle saves power and channel bandwidth)

Flood Early Warning Systems

A creek or river flood warning network can provide 30-120 minutes of advance warning to downstream communities:

1. Deploy water level sensors at upstream monitoring points (2-3 sensors per watershed)
2. Set alert thresholds: "Advisory" at 50% of flood stage, "Warning" at 75%, "Emergency" at 90%
3. Gateway node at the monitoring station forwards alerts to community mesh
4. Room server stores alerts and delivers to all connected community members
5. Integration with community alerting: Telegram bot, email, or siren activation

Case study framework: A network of 5 sensors along a 20-mile creek watershed, each transmitting hourly with a gateway node at the nearest road bridge, can provide the downstream community with actionable flood warnings that the National Weather Service may not provide until the event is imminent.

Data Management and Visualization

# Simple data pipeline for water monitoring:
# 1. Sensor node transmits JSON over LoRa mesh
# 2. Gateway node receives and publishes to MQTT
# 3. InfluxDB stores time-series data
# 4. Grafana displays dashboard with:
#    - Current readings per sensor
#    - Historical trend charts
#    - Alert status indicators
#    - Map overlay with sensor locations

# Sample InfluxDB query for flood alert:
# SELECT last("level_cm") FROM water_sensors
# WHERE "location" = 'upstream_north'
# AND "level_cm" > 180  # alert threshold