Storm Water Runoff and Deep Groundwater Drainage in Two Closed Basins

Abstract

Closed basins dotting the landscape of south and central Florida have aroused the interest of numerous hydrologists in the past. Lacking surface water drainage features such as creeks and natural streams, closed basins drain internally through the subsurface during storm events. Little is known, however, about the magnitude and role of subsurface drainage fluxes to deep groundwater aquifers. In this study, instruments were deployed to monitor the surficial and deep aquifer heads at groundwater discharge points in two urbanized closed basins. The purpose of the study was to develop and apply field methods to estimate rapid subsurface runoff following rainfall events and evaluate the effectiveness of internal drainage in urban drainage planning. The two sites were in Hillsborough County, Florida, and one location was a 6-m-deep sinkhole that receives urban runoff from the rest of the basin. The data captured rapid subsurface drainage exceeding 25 cm/day at these discharge locations following rainfall. The two locations collected subsurface runoff rapidly and released the runoff gradually into the deep aquifer system. Results have practical implications for urban drainage in closed basins.