Suspended sediment discharged from the 8.32-square-mile Salem Fork study area in Harrison County, W. Va., averaged 3,500 tons per year during the first 4-year period of investigation and 1,770 tons per year during the second 4-year period. The difference
as attributed to increased flow control, effected by the completion of detention structures and other conservation measures, the absence of appreciable sediment-producing construction activities, and a reduction of the amounts of rainfall and runoff during the second 4-year period. Particle-size distribution of the suspended sediment discharged from the watershed remained unchanged during the two 4-year periods. Although sand and some silt were deposited in upstream reservoirs, sands and other sediments were evidently entrained in the flow below the reservoirs.
During the 7.75-year period, reservoir 11A had a trap efficiency of 88 percent. The average annual sediment yield of subwatershed 11A was 1.31 tons per acre, or 837 tons per square mile. Outflow from reservoir 11A occurred during 81 percent of the investigation 'period, October 1954 to June 1962, and 78 percent of the sediment discharge from the reservoir occurred during less than 6 percent of the investigation period. A comparison of particle-size distribution of inflow sediment with that of outflow sediment revealed that practically all sands and some silts entering reservoir 11A were deposited in the reservoir. Chemical analyses of inflow water and the particle-size analyses suggested that flocculation of fine sediments occurred in the reservoir. Analysis of the sediment data collected at the outflow of reservoir 9 during 1956-62 revealed that the average annual sediment discharge was 128,000 pounds per year. Limited particle-size data suggested that practically no sand was discharged from reservoir 9, even though the inflow contained sand. Average annual inflow to reservoirs 11A and 9 compared favorably with average annual runoff for the entire watershed-study area.
Additional publication details
USGS Numbered Series
Fluvial sediment in Salem Fork watershed, West Virginia