Date of Award
Master of Science in Coastal Marine and Wetland Studies
Coastal and Marine Systems Science
Richard N. Peterson
Richard F. Viso
Susan M. Libes
It is well understood that urbanization results in changes to the hydrologic cycle, namely increasing surface runoff production rates. Precipitation falling on impervious areas is typically directed via a network of drainage pipes to detention reservoirs, a process shown to negatively impact aquifer recharge rates. Historically, urban hydrologists have focused primarily on surface processes with little consideration to subsurface implications of the urban water cycle. Here, we present an approach to construct long-term, high-resolution water budgets for a coastal stormwater catchment resolving surface runoff and groundwater fractions within the water body and associated source-specific fluid exports to the coastal ocean. We use the radiotracer 222Rn to delineate groundwater fraction within the reservoir, calculate direct precipitation inputs, and by difference, determine surface runoff contributions to the total water budget. By determining total output rates from Dogwood Swash, we also examine relative source outputs at both high- and low-resolution temporal scales from 2012 through 2013. While surface runoff constituted the majority of the water budget, both groundwater and surface runoff fractions varied by 36.5% suggesting the subsurface source to contribute significantly to the stormwater catchment fluid budget. However, long-term records indicate a decline in groundwater fraction (by 35%) and export (14%) from the system as aquifer residence times increased. Constructing water budgets for sub-basin tributaries within the larger Dogwood Swash drainage complex suggest reduced source water variability, lower groundwater fractions, and longer aquifer residence times with greater impervious surface area. Our approach to water budget construction may be applied to other environments providing the framework for source-specific material budgets. Such assessments could then be used by stormwater managers to best maintain desired ecosystem health in both urban streams and the coastal ocean.
Peterson, Leigha E., "Constructing Water Budgets for a Coastal Stormwater Catchment to Examine Temporal Dynamics Between Urban Groundwater and Surface Runoff" (2014). Electronic Theses and Dissertations. 41.