Quantifying floodplain floodplain floodplain floodplain floodplain floodplain flow resistance is critical to multiple is critical to multiple is critical to multiple is critical to multiple is critical to multiple is critical to multiple river management objectives, management objectives, management objectives, management objectives, management objectives, management objectives, but characterization of how characterization of how characterization of how characterization of how characterization of how characterization of how floodplain vegetation dissipates flow dissipates flow dissipates flow dissipates flow dissipates flow dissipates flow energy lacks comprehensive analysis. By utilizing lacks comprehensive analysis. By utilizing lacks comprehensive analysis. By utilizing lacks comprehensive analysis. By utilizing lacks comprehensive analysis. By utilizing lacks comprehensive analysis. By utilizing over 3.4 million 3.4 million 3.4 million 3.4 million 3.4 million 3.4 million discharge measurements, in conjunction with measurements, in conjunction with measurements, in conjunction with measurements, in conjunction with measurements, in conjunction with measurements, in conjunction with vegetation measurements from NASA’s measurements from NASA’s measurements from NASA’s measurements from NASA’s measurements from NASA’s measurements from NASA’s Global Ecosystem Dynamics Investigation Ecosystem Dynamics Investigation Ecosystem Dynamics Investigation Ecosystem Dynamics Investigation Ecosystem Dynamics Investigation Ecosystem Dynamics Investigation (GEDI), this study characterizes this study characterizes this study characterizes this study characterizes this study characterizes this study characterizes floodplain roughness and its roughness and its roughness and its roughness and its roughness and its roughness and its determinates across the continental United States. across the continental United States. across the continental United States. across the continental United States. across the continental United States. across the continental United States. Estimated values of the values of the values of the values of the values of the values of the floodplain roughness coefficient, Manning’s roughness coefficient, Manning’s roughness coefficient, Manning’s roughness coefficient, Manning’s roughness coefficient, Manning’s roughness coefficient, Manning’s n, are provided based on its provided based on its provided based on its provided based on its provided based on its provided based on its variation with with with with with with vegetation aboveground biomass and canopy aboveground biomass and canopy aboveground biomass and canopy aboveground biomass and canopy aboveground biomass and canopy aboveground biomass and canopy height for for for for for for different landscapes classes. Results show flow resistance in Results show flow resistance in Results show flow resistance in Results show flow resistance in Results show flow resistance in Results show flow resistance in floodplains decreasing as flow velocity increases but increasing with the decreasing as flow velocity increases but increasing with the decreasing as flow velocity increases but increasing with the decreasing as flow velocity increases but increasing with the decreasing as flow velocity increases but increasing with the decreasing as flow velocity increases but increasing with the fraction of vegetation inundated. A new function is proposed for predicting vegetation inundated. A new function is proposed for predicting vegetation inundated. A new function is proposed for predicting vegetation inundated. A new function is proposed for predicting vegetation inundated. A new function is proposed for predicting vegetation inundated. A new function is proposed for predicting n based of vegetation biomass, inundation fraction, and flow of vegetation biomass, inundation fraction, and flow of vegetation biomass, inundation fraction, and flow of vegetation biomass, inundation fraction, and flow of vegetation biomass, inundation fraction, and flow of vegetation biomass, inundation fraction, and flow velocity (RMSE = 0.024, (RMSE = 0.024, (RMSE = 0.024, (RMSE = 0.024, (RMSE = 0.024, (RMSE = 0.024, r2 = 0.74). This analysis provides evidence of = 0.74). This analysis provides evidence of = 0.74). This analysis provides evidence of = 0.74). This analysis provides evidence of = 0.74). This analysis provides evidence of = 0.74). This analysis provides evidence of key hydraulic patterns of hydraulic patterns of hydraulic patterns of hydraulic patterns of hydraulic patterns of hydraulic patterns of energy dissipation in floodplains, and dissipation in floodplains, and dissipation in floodplains, and dissipation in floodplains, and dissipation in floodplains, and dissipation in floodplains, and integration of the proposed function into of the proposed function into of the proposed function into of the proposed function into of the proposed function into of the proposed function into flood and habitat models may and habitat models may and habitat models may and habitat models may and habitat models may and habitat models may reduce uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.uncertainty.