Subsurface storage as a regulator of streamflow was investigated as an explanation for the large proportion of pre-event water observed in urban streams during storm events. We used multiple lines of inquiry to explore the relationship between pre-event water proportion, subsurface storage, and streamflow under storm conditions. First, we used a three-dimensional groundwater-surface water flow and transport model to simulate an idealized hillslope to perform model-based chemical hydrograph separation of storm flow. Second, we employed simple dynamical systems analysis to derive the relationship between subsurface storage and streamflow for three Baltimore watersheds (3.8-14 km2 in area) along an urban-to-rural gradient in the BES LTER. Last, we applied chemical hydrograph separation to high-frequency specific conductance data in nested urban watersheds (~50% impervious surface cover) of Dead Run, Baltimore County, Maryland.
Bhaskar, A.S. and C. Welty (2015), Analysis of subsurface storage and streamflow generation in urban watersheds, Water Resources Research, doi: 10.1002/2014WR015607.