Mean Size Distribution of Bed Load on Goodwin Creek

Goodwin Creek is a steep (bed slope of study reach = 0.003) gravel-bed stream in the bluff-line hills east of the Mississippi River floodplain in the north-central part of the state of Mississippi. Records of the flow for a nine-year period and 488 bed-load transport samples collected during a four-year period allow a comparison between weighted and nonweighted calculations of the size distribution of the bed load. The mean size distribution of the bed load on Goodwin Creek was calculated using the size distribution of the bed load weighted by transport rate and flow frequency. The size of the bed load was found to be slightly finer (D50 = 6.8 mm) than the bed subsurface (D50 = 8.3 mm) during the nine-year period. The weighting technique greatly reduced the bias (nonweighted D50 = 3.16 mm) in the calculation of the mean size distribution.