Tracing hydrological connectivity

Abstract

When investigating fundamental hydrological functions of catchments (i.e. collection, storage and release of water and matter), the spatial and temporal variability of hydrological connectivity is a key element (Black, 1997). Introduced in hydrology in the early 1980s by Burt & Gadiner (1982), the concept of hydrological connectivity has only recently attracted the attention of the scientific community. Over the past two decades, hydrological connectivity has become an important conceptual framework within which the spatial and temporal variability of streamflow generation and sediment transport can be conceptualised from a holistic perspective, considering the structural and functional connectivity between the Chapter structures and connectivity pathways (Cammeraat, 2002;Wohl et al., 2019). Failure in assessing these heterogeneities may lead to erroneous process conceptualisation and discrepancies between processes observed at smaller scales and responses that may occur at larger scales (Ward and Packman, 2019). Assessing system heterogeneities is also particularly important for restoration purposes (Ward and Packman, 2019;Wohl et al., 2019), since the management of systems' hydrological (and ecological) functions should account for this variability to be properly implemented.Recently, Wohl et al. (2019) and Blöschl et al. (2019) have highlighted the need to consider hydrological systems as borderless, in a way that the transition zones (or interfaces) between different landscape elements should be characterised for their own processes and fluxes to have a better perception of where and when connectivity may take place. Similarly, Krause et al. ( 2017) stressed the importance of system interfaces as "hot spots of ecological, biogeochemical and hydrological processes" arguing that an improved understanding of large-scale landscape interactions will only be possible once interface processes would be incorporated in system conceptualisation. Advancing hydrological connectivity understanding through interdisciplinary approachesWhen investigating hydrological systems connectivity, it is fundamental to consider the ecological and geomorphic components of the landscape and the way they interact with the hydrological components. In this sense, research on hydrological connectivity intrinsically requires a certain level of interdisciplinarity (i.e. incorporating knowledge and techniques from different disciplines) (Paton et al., 2019;Turnbull et al., 2018). During the last decade, several authors have emphasised the importance of interdisciplinary approaches -and of improving the dialogue between hydrologists and specialists of different disciplines -in order to further advance our understanding of hydrological connectivity (Cooper, 2010;Smith et al., 2019;Wainwright et al., 2011). More specifically, Wainwright et al. (2011) suggested that we should focus on developing new interdisciplinary approaches able to obtain information about the system's structure (spatial variability) and functions (both spatial and temporal va...