“…Thus, the human sensors concept implies that in hydrology, citizen science data are not always generated for a scientific purpose, in opposition to traditional monitoring practices. The human sensors component, representing a humanmachine-environment interface, provides qualitative and quantitative observations that can be used within quantitative hydrological studies, with careful attention to the accuracy and scale of these observations (Buytaert et al, 2014, Kosmala et al, 2016, Mazzoleni et al, 2019, Seibert and Vis, 2016). See Table 1 for the definition of 'human sensors'.…”