Open-Source, Low-Cost Sensor for Custom Water Level Monitoring in Observation Wells and Piezometers

摘要

Many commercial sensors exist for monitoring water levels in piezometers and wells. However, these sensors tend to be expensive and contain proprietary hardware and software that make customization by users difficult. Recently, the vast open-source Arduino programming community has enabled the development of highly customizable, low cost sensors with the precision and accuracy needed for scientific research. Here, an ultrasonic distance sensor is developed to monitor the water level in a 2” piezometer with sub-centimeter resolution, powered by a lead-acid battery and solar cell to record sub-minute time increments for duration of days to weeks. This sensor was developed specifically to identify centimeter-scale, daily fluctuations of the water table due to increased daytime evapotranspiration in fens and wetlands in central Oregon. Initially, condensation of water vapor caused the sensor to malfunction, but addition of a fan and humidity sensor was able to circulate air during times of high humidity and prevent condensation, mitigating the problem at the cost of higher power consumption. The open-source programming of the sensor is easily customizable by the user to optimize power management and time resolution to fit a wide variety of other specific tasks at a total package cost far below that of commercially available products.