Jinze, M.; Qingmai, M. Sediment delivery ratio as used in the computation of watershed sediment yield
Sediment delivered from gullied, hilly loess areas on the middle reaches of the Yellow River is essentially the product of gully erosion. In estimating the sediment delivery ratio of this area the total material eroded from the entire watershed is taken as the sum of the quantities yielded by way of sheet, gully and channel erosion.
Analyses and calculations for typical watersheds in the aforementioned area show that wash load comprises over 95% of the total sediment load during most floods, with the result that the floods are frequently of hyper-concentration (average sediment content during a flood being no less than 500 kg/m3). This is due to the mechanism of particle suspension, and is the basic reason why the sediment delivery ratio is nearly equal to unity.
Finally, a formula for computing a modified sediment delivery ratio in the study areas, obtained through correlation analyses and considered to be acceptable, is presented.