Input data on watershed drainage area characteristics and stream reach geomorphometry for statistical modeling of floodplains, streambanks, and streambeds in the Chesapeake Bay and Delaware River watersheds of the U.S. Mid-Atlantic. Characteristics include selected upstream accumulated attributes (with divergence routing) describing geology, topography, soils, hydrology, and land use for each NHDPlusV2 stream reach from Wieczorek et al. (2018), and the geomorphometry of the local stream reach summarized from Hopkins et al. (2020). These potential predictors were tested for incorporation into Random Forest statistical models to explain and predict spatial variation in floodplain and streambank flux of sediment, fine sediment, sediment-C, sediment-N, and sediment-P and rates of geomorphic change, and streambed sediment characteristics (d50, cover by fine sediment, cover by fine and sand sediment).