Circulation and water renewal of Florida Bay, USA

Abstract

The circulation and exchange processes controlling transport and water renewal within the western subregion of Florida Bay, USA, are presented and compared to our previous findings for the north-central and northeast subregions of the bay. We find there is a common bank/basin flow response to wind forcing that is the primary driver of water renewal for each of the regions studied. Florida Bay is a patchwork of shallow basins surrounded by very shallow banks that are cut through with deeper channels connecting to nearby basins. We observed that, for each subregion studied, there was a net downwind basin outflow through the larger channels that was approximately balanced by a net basin inflow over the surrounding shallow banks. The resulting basin through flows are used to estimate exchange times for renewal of western basin waters of approximately 1 mo. This exchange time is sufficient to prevent hypersalinity and degradation of water quality in the western basin, in contrast to the north-central subregion, where hypersalinity development is an annual occurrence. Our results highlight the importance of wind induced water renewal in shallow coastal bays with weak to moderate tidal exchange. In addition, we have discovered a significant clockwise circulation pattern through the western basins from strong inflows of coastal waters through Flamingo Channel that turn southward through the western basins before rejoining the coastal flow toward the Florida Keys tidal passages and Atlantic coastal zone. A practical solution to control hypersalinity, sea grass die-off, and water quality degradation of Florida Bay is proposed.