The effects of current landscape configuration on streamflow within selected small watersheds of the Atlanta metropolitan region

Study regionThis study investigated impacts of current landscape configuration on streamflow within selected small watersheds of the Atlanta, Georgia metropolitan region (AMR).Study focusTo determine effects of current landscape arrangement on watershed-wide Hydrologic Unit Code (HUC)-12 land cover/land use (LC/LU), the configurational metric of contagion was chosen. Contagion-adjusted curve numbers (CNs) were calculated for all 405 HUC-12 watersheds in the AMR. 6 watersheds were chosen for Thornthwaite Water Balance (TWB) model evaluation based upon having a stream gage record of the 5 year (60 month) period most closely associated with contagion and CN values derived from the 2011 National Land Cover Dataset (NLCD). 4 watersheds out-performed their original CN watershed simulations based upon: Nash–Sutcliffe efficiency (NSE); room mean square error (RMSE)-standard deviation ratio (RSR); and Akaike Information Criteria (AIC) analysis.New hydrological insightsConfigurational metrics related to contagion of the aggregation index (AI) and clumpiness index (CI) indicated possible reasoning to explain differences found between the 4-watershed and 2-watershed categories. The AI of agricultural LC/LU within the 2-watershed category suggested greater landscape heterogeneity due to agricultural patch disaggregation, whereas the CI suggested greater overall disaggregation and landscape dispersion for all non-water LC/LU patches within the 2-watershed category and pointed towards greater landscape heterogeneity driven by higher dispersal of non-water patches. Both may lead to complex flow patterns not easily estimated within streamflow simulations.