How a Low-Cost Arduino System can Start a New Project and Save an International Field Season

Abstract:

In-situ sensors for hydrological field work can be costly, particularly for long-term or large-scale projects. Novel or high-risk projects may not be feasible due to the prohibitively high cost of commercial monitoring equipment. For long-term field studies in remote locations, there is also the risk that the expensive monitoring equipment could be lost, stolen, or destroyed while deployed.

Here we demonstrate the use of a sensitive, accurate, 6-sensor Arduino-based soil temperature and humidity array that costs less than $80 USD. Our system can be easily expanded with additional sensors and has good data stability. This array provides accurate data at higher resolution and precision relative to what can be obtained with typical off-the-shelf sensors (e.g., iButtons), at about 1/10 the price. Our initial sensor array design had only temperature and humidity sensors; however, the flexibility of Arduino allows the addition of many sensor types depending on the field application. Our recent improvements to the design include a photodiode to identify sunrise and cloud shading, and barometric pressure sensors to allow calculation of potential temperature. Our sensor array incorporates datalogging to a microSD card, which provides a higher storage capacity and prevents data loss if there is an interruption in power. Additional redundancy could also be implemented in the form of a second microSD card or cellular communication hardware for real-time data logging and monitoring.

This design was a last-minute addition to a recent field program in the Atacama Desert, and has provided one of the most robust and meaningful datasets from that field season. The custom-built design allowed us to address specific questions and retrieve reliable data with limited development time. In fact, the temperature and humidity sensors used here provided increased data precision and transformed our understanding of water dynamics in this very dry environment.

Here we show that a foundational knowledge of circuits and coding paired with some basic soldering skills can be instrumental in answering key hydrological or geophysical questions. In addition, an $80 Arduino design may just end up saving your international field season!