Depressional Wetlands and Episodic Flows: Conceptual Hydrologic Model for The Dougherty Plain of Georgia

摘要

The Dougherty Plain physiographic province of southwest Georgia has karstic topography with deeply incised streams, deep sandy regolith with interbedded clay lenses, and permeable, vuggy carbonate bedrock. Hydrologic studies on the Dougherty Plain have focused on groundwater-stream interactions and the hydrologic effects of center-pivot irrigation. Yet, over 12,000 depressional wetlands, of widely ranging size and shape, may contribute substantially to regional hydrology. Despite their wide distribution, depressional wetlands (and episodic surface flows through these wetlands) have not been well studied. We use our current hydrologic understanding of the Dougherty Plain to propose a conceptual model of episodic flows through depressional wetlands that incorporates three elements: 1) Depressional wetlands are important local (and regional) components of the surface hydrology; 2) Episodic flows connect depressional wetlands to perennial streams, contributing substantial fluxes of material and energy to downstream waters; and 3) Groundwater is an important factor that discharges into, and is recharged by, depressional wetlands. This conceptual model will likely improve our understanding and management of surface and subsurface hydrology on the Dougherty Plain.