A LOW-COST, DIY ULTRASONIC WATER LEVEL SENSOR

A low-cost (~$100), do-it-yourself (DIY) ultrasonic water level sensor/datalogger has been designed, constructed, and tested for use in education, citizen/community science, and research settings. The sensor package comprises an ultrasonicdistance sensor, a microcontroller running Arduino firmware, a micro-SD card for dat-alogging, a real-time clock for timekeeping and sleep functions, and an OLED screenfor real-time display. Electronics are housed in low-cost custom containers using eitherupcycled plastic containers or laser-cut acrylic. Reported ultrasonic sensor accuracyis 5 cm across a range of 15–645 cm, with an estimated power budget of 76 days ofoperation on a rechargeable 10 amp-hr battery. The DIY sensor has been field testedalongside two commercial sensors for 18 days in Wilmington, North Carolina, includ-ing during Tropical Storm Colin, with all sensor measurements in close agreement(e.g., root mean squared error of 1.5 cm between the DIY sensor and a proven commer-cial unit). Potential applications, design and construction, and deployment recommen-dations for the sensors are described, as well as simple and inexpensive modificationsto the sensor and its packaging that could further improve performance. Preliminarylesson plans written to accompany the device for high school- and undergraduate-leveleducational projects are available.