Streambed Median Grain Size (D50) across the Contiguous U.S.

The streambed median grain size (D50) has been an integral part of many sediment transport and stream power equations seeking to characterize channel stability conditions. However, its previous usage is constrained by regional applicability, localization datasets, a limited number data points. This study uses large geographically diverse set (n > 2400), from five published sources, present quantitative information assess the distribution D50 across contiguous U.S. Spatial was analyzed based on three frameworks: Physiographic Provinces, Level III Ecoregions, Hydrologic Landscape Regions (HLRs). Gravel found be dominant material in most Provinces. with humid climate, permeable soil, plateaus exhibit higher average than regions other geologic texture, landscape forms. Further analysis all using smoothed spatial maps showed dominance sand fine gravel streams located central southern U.S., coarse cobbles northeastern