Summary of sediment yield data from forested land in the United States [Sediment deposition in forest streams, forest soil erosion measurements]

Statistical analyses were made on 812 forest soil erosion measurements and estimates of sediment yield in forest streams. More than 100 of those reports showed that streams draining forested land along the Pacific Coast yield far more sediment per unit area of watershed than do streams of forested regions elsewhere in the nation. In the other 700 reports, no significant differences (P=0.05) were found among sediment yields in streams draining predominantly forested land of the eastern United States and of western regions other than the Pacific Coast. About one-third of these eastern and western observations denoted sediment yields not exceeding 0.02 ton per acre per year, and three-fourths of the total did not exceed 0.25 ton. About one-fourth fell between 0.25 and 1.00 ton, and a few exceeded 1.00 ton per acre annually. Nonforest land use within some of the larger watersheds may account for many of the higher sediment yields. These nationwide results are consistent with regional compilations. A long-term average of not more than 0.25 ton per acre per year in streams of the eastern and western United States (but not of the Pacific Coast) can provide a first approximation of sediment yield from predominantly forested land. Amounts derived by prediction equations should be questioned if they greatly exceed 0.25 ton per acre per year.