Understanding Spatial and Temporal Drivers of Stream Intermittency and Connectivity in Urban River Networks

Urban development transforms catchment hydrology, disrupting natural flows and complicating stormwater management. Hydrological alteration and climate change are making urban systems drier and increasingly intermittent, yet highly modified, low-gradient river networks remain poorly understood, limiting effective, context-specific strategies. We investigated how urban land cover, subsurface characteristics, and antecedent weather influence ephemeral stream dynamics to identify the drivers of urban intermittency and strengthen sustainable water management. Contrary to expectations, tributaries with less impervious cover were more intermittent due to enhanced infiltration in permeable soils and paleo-sand deposits, underscoring the role of subsurface conditions in stream connectivity. Active drainage length correlated with antecedent rainfall and effective precipitation over 1–60 days, peaking at six days, indicating that stream expansion reflects hydrologic accumulation more than immediate runoff. These findings show that hydrometeorological and subsurface conditions jointly control urban stream connectivity, offering a stronger foundation for better understanding driving processes and building urban watershed resilience.