Located in Florida's panhandle, the Apalachicola River is the southernmost reach of the Apalachicola-Chattahoochee-Flint (ACF) River basin. Streamflow and sediment drains to Apalachicola Bay in the Northern Gulf of Mexico, directly influencing the ecology of the region, in particular seagrass and oyster production. The objective of this study is to evaluate the response of runoff and sediment loading in the Apalachicola River under projected climate change scenarios and land use / land cover (LULC) change. A hydrologic model using the Soil Water Assessment Tool (SWAT) was developed for the Apalachicola region to simulate daily discharge and sediment load under present (circa 2000) and future conditions (circa 2100) to understand how the system responds over seasonal and event time frames to changes in climate, LULC, and coupled climate / LULC. These physically-based models incorporate a digital elevation model (DEM), LULC, soil maps, climate data, and management controls. Long Ashton Research Station-Weather Generator (LARS-WG) was used to create downscaled stochastic temperature and precipitation inputs from three Global Climate Models (GCM), each under Intergovernmental Panel on Climate Change (IPCC) carbon emission scenarios for A1B, A2, and B1. Projected 2100 LULC data provided by the United States Geological Survey (USGS) EROS Center was incorporated for each corresponding IPCC scenario. Results indicate climate change may induce seasonal shifts to both runoff and sediment loading, acting to extend periods of high flow and minimum sediment loadings or altering the time at which these events occur completely. Changes in LULC showed minimal effects on flow while more sediment loading was associated with increased agriculture and urban areas and decreased forested regions. A nonlinear response for both streamflow and sediment loading was observed by coupling climate and LULC change into the hydrologic model, indicating changes in one may exacerbate or dampen the effects of the other. Peak discharge and sediment loading associated with extreme events showed both increases and decreases in the future, with variability dependent on the GCM used. Similar behavior was observed in the total discharge resulting from extreme events and increased total sediment load was frequently predicted for the A2 and A1B scenarios for simulations involving changes in climate only, LULC only, and both climate and LULC. Output from the individual GCMs predicted differing responses of streamflow and sediment loading to changes in climate on both the seasonal and event scale. Additional region-specific research is needed to better optimize the GCM ensemble and eliminate those that provide erroneous output. In addition, future assessment of the downscaling approach to capture extreme events is required. Findings from this study can be used to further understand climate and LULC implications to the Apalachicola Bay and surrounding region as well as similar fluvial estuaries while providing tools to better guide management and mitigation practices.
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Master of Science (M.S.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Civil Engineering; Water Resources Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Hovenga, Paige, "Response of Streamflow and Sediment Loading in the Apalachicola River, Florida to Climate and Land Use Land Cover Change" (2015). Electronic Theses and Dissertations. 5171.