Rivers and resilience: A longer term view from the drylands

Some previous assessments of dryland river resilience have focused on potential future adjustments to river flow regimes but consideration of the associated adjustments to river geomorphology (e.g. natural channel-floodplain structures) that may also influence riverine ecology or human land use is less common. How can we close this conceptual and practical gap to help enhance river management decision making? Here, we focus on Southern Hemisphere case studies where aerial image interpretations, field investigations, palaeohydrological calculations and geochronology have enabled reconstructions of dryland river responses to changing Holocene hydroclimates. We examine how knowledge of these river responses may provide important insights for improved conceptual definition and practical application of resilience thinking in dryland fluvial geomorphology and cognate disciplines. In particular, we: (1) demonstrate the range of past – and possible future – dryland river responses under changing boundary conditions and forcings; (2) highlight the significance of distinguishing between dryland ‘river behaviour’ and dryland ‘river change’ when considering resilience; (3) stress the importance of identifying proximity to quantified geomorphic thresholds to help distinguish between ‘river behaviour’ and potential ‘river change’; and (4) identify key conceptual and data gaps that need to be addressed to ensure better uptake of these insights in research and management.