Alternate Title

Tidal and Wind-Driven Circulation through Lignum Vitae Basin, Florida Bay


Current meter time series collected between1995 and 2001 are used to describe the exchanges of water through five tidal channels that connect Lignum Vitae Basin, a large subbasin in eastern Florida Bay, with adjacent subbasins and Atlantic shelf waters. Current data were combined with measured or simulated water levels, and channel geometry measurements were incorporated, to quantify volume transport through the channels. Results indicate a long-term inflow to Lignum Vitae Basin from the northwest through Gopher Keys Cut at an average rate of + 11.9 m3 s-1 during a 13-mo study period and from the west through South Twin Keys Cut at +9.6 m3 s-1 during a 7-mo study period. A quasi-steady long-term outflow was observed to the east through Steamboat Channel, to the southeast through Indian Key Channel, and to the southwest through Bowlegs Cut. Outflow rates averaged -7.1, -25.8, and -6.5 m3 s-1, respectively, through these three channels. Interactions between tidal water-level fluctuations and ebbs or floods resulted in a tide-induced outflow from Lignum Vitae Basin through Gopher Keys and South Twin Keys cuts at rates of -0.06 and -0.09 m3 s-1, respectively. Tidal residual inflows of +5.8, +0.11, and +0.04 m3 s-1 were calculated for Indian Key Channel, Steamboat Channel, and Bowlegs Cut, respectively. Comparisons of local winds with channel transport indicate that winds from any direction will force water through every channel except Steamboat Channel over most time scales greater than about 2 d. Flow through Steamboat Channel was coherent only with winds out of the northeast quadrant over time scales greater than about 1 d. Longterm flow was generally upwind through all channels except Bowlegs Cut.