Correction for Sediment Yield Bed Load Calculation
For sediment yield bed load computation, the unit sediment bed load [i.e., qs (cfs/ft)] should be multiplied by the average width to obtain the bed load (Qs). However, in DDMSW version 4.8.2, the top width is used instead of the average width. This may increase the bed load incorrectly.
Before the next version of DDMSW is released in 2016, users may develop a simple Excel to estimate the bed load (qs) based on the qs, flow area, and flow depth results from DDMSW 4.8.2. The average width can be computed by dividing the flow area with the flow depth. The bed load estimation should be applied individually to the main channel, left overbank, and right overbank. The total bed load is the sum of the individual bed loads of the main channel, left overbank, and right overbank. The final bed load volume (Vs) can be estimated by Vw*Qs/Qw where Vw is the runoff volume, Qw is the runoff peak, and Qs is the bed load (cfs).