Abstract:
Land-use and land-cover (LULC) change is a continuous and dynamic process that is driven by human-induced activity. The North River watershed, located in Alabama, exemplifies patterns of forestry practices related to commercial logging that are present with the increasing frequency of intensive forestry practices across the Southeastern U.S. While many studies focus on expanding urbanization within watersheds and the effect on hydrology, there is a need to study effects on hydrology of newer forestry practices, which promote shorter regeneration and growth periods with more frequent tree harvest. Using the Soil and Water Assessment Tool (SWAT), a GIS hydrologic modelling program using watershed data (LULC, soil weather, elevation), a calibrated and validated model (NSE: 0.74 and 0.63, respectively) was produced and run for the study period of 2001-2018. LULC change trends between six NLCD LULC change periods (2001 to 2004, 2004 to 2006, 2006 to 2008, 2008 to 2011, 2011 to 2013, and 2013 to 2016) were examined and the impact on both discharge and water-balance components were analyzed. Using a KS-test on the distribution of climate de-trended monthly simulated discharges, three LULC change scenarios revealed statistically different distributions. With net forest loss in the watershed, water yield and subsequent discharge values increased; scenarios with forest gain resulted in water yield and discharge decreasing through various water-balance components analyzed in SWAT. These results suggest that LULC change can have effects on the hydrologic cycle with impacts on water yield through alteration of the water-balance variables.
