Horizontal Groundwater Flow Patterns Through a Cypress Swamp‐Pine Flatwoods Landscape

Abstract Groundwater movement in the surficial aquifer of the lower Coastal Plain cypress swamp‐pine flatwoods landscape of the southeastern USA is poorly documented. This study was conducted to define the patterns of horizontal groundwater flow through a typical landscape with particular attention to water exchange between cypress swamps and the surrounding areas. One hundred and twenty shallow water table wells 1 m deep were installed in a 42‐ha study area, one‐third of which was covered by pond cypress ( Taxodium ascendens Brongn.) swamps. Water tables were measured approximately every 2 wk for 2 yr and the data were used to map water table elevation. Directions of horizontal groundwater flow were inferred from the water table topographic maps. Measured hydraulic heads were combined with saturated hydraulic conductivities to estimate groundwater flux. Most of the groundwater flowed through the swamps in response to the generalized surface elevation pattern. For selected ponds, the ground‐water also flowed from the swamps to the surrounding areas. It was uncommon for groundwater to flow into the ponds from the entire surrounding area. The pattern of groundwater exchange between the swamps and the surrounding area was related to the average water table depth: the deeper the average water table, the greater chance for groundwater to flow from the swamp into the surrounding area. Waterflow rates were estimated to be <56 cm d −1 . These groundwater flow patterns are different from the generally accepted pattern of water flow and should be useful in defining the hydrologic cycle of these landscapes.