Universal rainfall loggers gekk0-r

Rainfall monitoring stations are a critical component of operational flood early warning systems (EWS) and climate resilience initiatives, especially in mountainous landscapes where rainfall patterns are complex. Furthermore, in data-scarce regions they are necessary to properly define warning thresholds that might otherwise only be based on hazard assessment models. However, use of traditional proprietary-technology rainfall monitoring stations can be challenging due to operational and resource-related limitations. In this paper, we describe gekk0-r, a data logging and communication system designed to support the use of (potentially any) commercially available rain gauges to operate as a quasi-automatic rainfall station as part of a monitoring network. gekk0-r uses open and free technologies to record without any degradation of data quality. It is controlled by a Raspberry Pi microcomputer with a custom-made printed circuit board (PCB) as a hat for easy connection with the selected rain gauge. It can send data to web platforms through the cellular network or any other available internet connection. To demonstrate its performance, we conducted a calibration experiment in a laboratory setting which showed that the combination of the gekk0-r logger with a commercial rain gauge achieved World Meteorological Organization (WMO) standards for rainfall intensity measurements.