Response and Recovery of Watersheds to Environmental Change

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Increased attention to human-induced environmental change has highlighted the need to understand more completely the nature and rate of responses of critical systems to changing environmental conditions. Among the relationships for which greater knowledge is needed are responses of hydrologic systems to changes in the land uses within drainage basins. This project will analyze the dynamics of watershed response to during the last century in southwestern Georgia, where rapid deforestation occurred in the mid- to late-1800s, leading to a deep, intricate system of gullies and canyons. In recent decades, however, logging and agricultural activity in the area have diminished substantially, causing less dramatic but nonetheless significant changes in runoff regimes. Fieldwork in the area will provide information for more accurate dating of land-use disturbances and fluvial responses. Sediment samples of valley fill and terrace sequences will be dated through dendrochronologic and aerial photographic analyses. Land-use changes will be identified using tax records and aerial photos. Data from these investigations will be related to topographic and climatic data using a modified hydrologic model. This project will contribute to both theoretical and empirical understandings of the conditions that promote fluvial geomorphic instability. It also will contribute to new knowledge about the lag times of response and recovery when watershed characteristics change through human activity.