Streamflow (De)generation—How Do Streams Lose Flow?

Abstract

Streamflow loss is a key process for stream drying and has been studied across various environments and scales. So far, there has been little effort to conceptualise processes that lead to streamflow loss. To address this gap, we introduce a conceptual framework of streamflow degeneration based on subsurface characteristics governing the capacity to convey streamflow inputs and the boundary conditions of the reach. Using the capacity to convey streamflow inputs to distinguish between processes of streamflow loss is consistent with the conceptual framework of streamflow generation, where precipitation serves as the primary input. We show how six distinct streamflow loss processes modify a hypothetical hydrograph along a stream reach under idealised conditions. Using the streamflow degeneration framework, we propose fieldwork and modelling to address key questions on the importance of streamflow loss. This conceptual framework provides a common vocabulary to the community to facilitate comparisons between sites, generalise findings across environments and scales, and ultimately enhance our understanding of where and why streamflow loss occurs.