Brief Communication: Investigating the invisible subsurface stormflow process through a thorough and systematic study across sites and scales

Abstract. Subsurface stormflow (SSF) is one of the least studied and therefore least understood runoff generation processes because detecting and quantifying SSF is extremely challenging. However, the impact of SSF on streamflow dynamics and water quality is much larger than commonly assumed. The hydrologic community should therefore not shy away from the challenge to monitor SSF, but should instead join forces, make creative use of novel sensing techniques and systematically tackle the investigation of this elusive process. While this endeavor is high in effort and risk, it also comes with the potential of high gain. We here describe the challenges and propose a possible way forward.