In coastal areas with shallow water tables and low gradient topography, surface and groundwater coupling complicates the feasibility of pre- and post-development flow prediction, including peak flow rates. Groundwater-surface water interactions (pathways and contributions of each during a storm event) are not appropriately considered in the stormwater management practice selection and design process.
Objectives of this continuing project include actions to (1) utilize storm hydrograph separation techniques (surface and groundwater) for data collected from two comparable headwater streams draining coastal watersheds (one is slated for and is partially comprised of existing development, the other has no existing or planned development), (2) compare and contrast groundwater-surface water interactions within and between these two coastal first-order watersheds, both with shallow water tables, but each with differing yet related soil types, (3) characterize the utility of modified SCS curve numbers (CN) within respective watersheds for rainfall-runoff estimates based on previously collected data and compare to other methods currently being developed for low-gradient systems in the lower coastal plain, (4) determine the general feasibility, with respect to water quantity and quality, of enhanced infiltration versus retention and storage based on soil and water interactions, and (5) disseminate project results to regulatory agencies, local county and municipal planning and public works staff, other professional decision-makers, such as developers, engineers, surveyors, and landscape architects, and educators including extension specialists.