Application of SWAT-MODFLOW for evaluating the impacts of climate change on the surface- and groundwater resources of the lower Apalachicola Chattahoochee Flint River Basin, USA
Abstract
Impacts of climate change is a critical concern for the long-term agricultural and environmental sustainability in the lower Apalachicola-Chattahoochee-Flint (ACF) River Basin of southeastern U.S. Understanding the potential impacts requires a modeling system that can adequately simulate the surface- and groundwater (SW-GW) resources simultaneously due to the intrinsic connection between the resources in the region. This study developed a SWAT-MODFLOW model for the lower ACF River Basin and the underlying Upper Floridan aquifer and evaluated the impacts of climate change predicted under RCP4.5 and RCP8.5 scenarios on streamflow, SW-GW exchange, evapotranspiration (ET), and groundwater recharge. Streamflow evaluation after calibration at six locations showed that the model can adequately replicate streamflow in the region. The model, however, performed better in regions where the aquifer was thick and had less variability in groundwater levels. Comparison against 2,360 observed daily groundwater levels showed that the model also adequately simulated groundwater levels in the Upper Floridan aquifer. Assessment of historic (1979-2005) temperature to predicted under both scenarios (2041-2060) showed an increase in daily maximum temperature by as much as 2.7 . A shift in precipitation pattern with increased precipitation from July-Oct and reduction from April-May was also predicted. Evaluation of streamflow predicted a reduction in flow in the late spring and summer months (March-July) but an increase in the late fall (Sept-Nov) and early months (Jan-Feb) under both climate scenarios indicating to a shift in flow pattern. Considerable increase in streamflow during high flow events was also predicted. An increase in groundwater recharge was predicted throughout most of the model domain leading to an increase in SW-GW exchange. Highest flux changes (~50%) were observed in the losing streams indicating to a reduction in loss of water from the streams to the aquifer. Although an increase in annual groundwater recharge and SW-GW fluxes is predicted under future climate, reduction in monthly streamflow for the months of March-July indicates to the possibility of reduction in groundwater recharge and SW-GW fluxes in certain months of the year. Minimal change in ET was predicted ranging from about -4% to 4%.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H14A..03K