Development of a grid-cell topographic surface for Okefenokee Swamp, Georgia

The Okefenokee Swamp is at 160,000 ha freshwater wetland in Southeast Georg ia, USA that developed in a landscape basin. Hydrologic variability across the swamp suggests that water-surface elevations are not uniform across the swamp. The topographic surface map discussed herein was developed to descr ibe the swamp topography at local to landscape scales and relate the swamp peat- and sand-surface elevations to elevation above mean sea level. These data were then used to relate water-surface elevations across the swamp so that the swamp hydrologic environment could be described spatially and temp orally with a spatial hydrology model. The swamp was divided into 5 sub-bas ins that reflect similar seasonal hydrodynamics but also indicate local con ditions unique to the basins. Topographic gradient influences water-level d ynamics in the western swamp (2 sub-basins), which is dominated by the Suwa nnee River floodplain. The eastern swamp (3 sub-basins) is terraced, and th e regional hydrology is driven less by topographic gradient and more by pre cipitation and evapotranspiration volumes. The relatively steep gradient an d berm and lake features in the western swamp's Suwannee River floodplain l imit the spatial extent of the Suwannee River sill's effects, whereas syste m sensitivities to evapotranspiration rates are more important drivers of h ydrology in the eastern swamp.