Evaporometer | A Wireless Mesh of Open-Source Rainfall/Evaporation Gauge and Sensor Suite for In Situ Near-Real-Time Environmental Data

Access to in situ near real-time environmental sensor data in remote locations provides invaluable utility in the fields of agricultural and environmental sciences. For studies where data needs to be gathered frequently, it could be costly and dangerous to take numerous trips into the field to collect this information and to inspect multitudes of distributed devices to ensure proper operation. One solution is to develop remote sensors capable of transmitting data and status updates (like battery level) over long distances from unserviced locations to a receiver hub to be accessed in near real-time online. The Openly Published Environmental Sensing Lab at Oregon State University (OPEnS Lab) produced a low-cost Open Source environmental sensing station called the Evaporometer that collects data at precisely timed intervals including rainfall amount, rate of evaporation, temperature, humidity and light (IR and Visible spectra), while CO2 and other sensors are also being evaluated for inclusion. This project focuses on the development and deployment of the prototype Evaporometer in HJ Andrew's Experimental Forest located in Blue River Oregon. The Evaporometer was designed for efficiency and succeeds in systematically collecting environmental data in hard to reach places over long periods of time. A real time clock interrupt enables the device to enter and exit "sleep mode", allowing Evaporometers to remain in the field over long periods of time and controlling the how frequently data should be collected. A load cell measures the weight of collected water in a container. This container is tightly packed with a fiberglass wick, which draws water from the bottom to the surface for efficient evaporation. A siphon has been designed into the container to prevent any possible water overflow situations and lost collected rainfall. All data collection and transmission processes are handled by an Adafruit Feather development board equipped with a long range, low power wireless (LoRa) radio that sends encrypted data via 900MHz ISM band. This data can be transmitted up to 20km to a receiver hub with an internet connection, and uploaded directly to Google cloud storage or other online data services for convenience.