MENGUJI DIGITALISASI DATA PICHE EVAPORIMETER SEBAGAI DASAR PERHITUNGAN EVAPOTRANSPIRASI REFERENSI MENGGUNAKAN SENSOR LOAD CELL

Abstract

Evaporation measurements using a Piche evaporimeter at the East Java Climatological Station are still performed manually, making the process susceptible to human error and preventing continuous data recording. This study developed a digital Piche evaporimeter system based on a load cell sensor integrated with an HX711 analog-to-digital converter (ADC), an ESP32 microcontroller, MicroSD storage, and a MySQL-based web interface. The system employs a two-stage filtering approach consisting of a Median Filter and an Exponential Moving Average (EMA, α = 0.05) filter to stabilize the sensor signal. Evaporation was calculated from the water mass loss measured at two-hour intervals and subsequently converted into reference evapotranspiration (ET₀) estimates using the Piche coefficient. Comparative testing demonstrated an average error of 0.01% with a coefficient of determination (R²) of 99.9975%. During the observation period from 1 to 5 July 2026, the system recorded daily evaporation values ranging from 3.07 to 3.86 mm and estimated ET₀ values ranging from 2.15 to 2.51 mm day⁻¹. These results demonstrate that a low-cost, automated, and accurate evaporation monitoring instrument can support climatological observations for educational purposes and community-scale agricultural applications.