Towards an improved understanding of biogeochemical processes across surface-groundwater interactions in intermittent rivers and ephemeral streams

Surface-groundwater interactions in intermittent rivers and ephemeral streams (IRES), waterways which do not flow year-round, are spatially temporally dynamic because of alternations between flowing, non-flowing dry hydrological states. Interactions surface groundwater often create mixing zones with distinct redox gradients, potentially driving high rates carbon nutrient cycling. Yet a complete understanding how underlying biogeochemical processes across surface-groundwater flowpaths IRES differ among various states remains elusive. Here, we present conceptual framework relating spatial temporal variability water-groundwater to processing hotspots IRES. We combine review theIRES biogeochemistry literature concepts hydrogeomorphology to: (i) outline common distinctions IRES; (ii) use these distinctions, together considerations carbon, nitrogen, phosphorus cycles within IRES, predict the relative potential for different reach-scale (flowing water, fragmented pools, hyporheic zones, groundwater, emerged sediments); (iii) explore entire networks. Our approach estimates greatest when reaches into isolated water highlights relatively understudied such as sediments. Furthermore, fluvial networks dominated by is likely more than variable. conclude that research would benefit from focusing on cycles, states, consideration network architecture. outlines opportunities advance studies expand