# Real-World IoT Applications # 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 ``` # Air Quality and Environmental Monitoring Networks Urban air quality monitoring is an underserved application for community mesh networks. Low-cost sensor nodes can build hyperlocal air quality maps that government monitoring stations - typically spaced miles apart - cannot provide. ## Why Low-Cost Sensors Matter The EPA and state agencies typically maintain one air quality monitoring station per 100+ square miles in urban areas. These stations are highly accurate but expensive (~$100K per station) and capture only regional averages. Community mesh nodes with low-cost sensors ($50-200 per node) can provide neighborhood-level data that reveals hotspots, traffic corridors, and industrial emission events invisible to the regional monitoring network. ## Sensor Options for Air Quality
ParameterSensorCostAccuracyNotes
PM2.5 / PM10Plantower PMS5003 or SDS011$15-25±10 µg/m³Most important for health; needs temperature correction
CO₂Sensirion SCD40 or SCD41$35-50±50 ppmTrue NDIR sensor; accurate without calibration
VOCsSGP30 or SGP41$15-20Semi-quantitativeGood for trend and event detection; not precise absolute levels
NO₂ / O₃Spec Sensors electrochemical$50-100 each±20 ppbHigher cost; good for near-road monitoring
Temp + HumidityBME280 or SHT31$3-8±0.5°C, ±3% RHEssential for correcting PM sensor readings
## Building a PM2.5 Monitoring Node ``` # Hardware: RAK4631 + RAK1906 (BME680) + external PMS5003 # Connect PMS5003 to UART on RAK19007 base board # RAK1906 provides temperature/humidity for PM correction # MeshCore SENSOR firmware sends telemetry packets # Meshtastic: use Telemetry module with custom I2C sensor support # Or: use ESP32 (T-Beam) running custom Arduino firmware that # packages PMS5003 + BME280 data into Meshtastic environment telemetry format # Meshtastic custom telemetry (advanced): # Modify device firmware to include PMS5003 data in telemetry packets # Or: use a Raspberry Pi co-processor that reads PMS5003 via UART # and injects formatted messages into the mesh via Python API ``` ## Community Air Quality Network Design For a neighborhood-scale (10-50 node) air quality network: - **Spatial coverage:** 1 node per 0.5-1 km² in residential areas; denser near industrial sources and major roads - **Transmission interval:** 5-15 minutes (PM sensors need averaging to reduce noise) - **Data aggregation:** Central room server or MQTT gateway with InfluxDB backend - **Public dashboard:** Grafana public dashboard showing real-time map (use Leaflet.js for geographic visualization) - **Calibration:** Collocate 2-3 nodes with nearest EPA monitoring station for 2-4 weeks to develop calibration coefficients ## Community Value and Partnerships - Share data with PurpleAir, AirNow, or OpenAQ platforms for broader visibility - Partner with local universities for calibration studies and data analysis - Provide data to neighborhood environmental justice organizations - Submit findings to local air quality district as citizen science data