ABSTRACT
Sediment terminal velocity is a key parameter responsible for quantity of sediment sustained by the flow in open channels. Even minor changes in the value of fall velocity (F.V), when calculated by different methods, lead to significant variation in estimated total sediment transport/flow rate. Thus, many attempts have been made to estimate fall velocity precisely. In the present study, effect of fall velocity in predicting total STR is determined by using different fall velocity equations such as Cheng (1997), Julien (1995), Zhang (1989) Concharov (1962[Ibadzade1992]), Soulsby (1997), Van Rijn (1989), & Zhu & Cheng (1993) for wide range of data sets. Effect of fall velocity on the total STR is largely observed in Shu-Qing Yang and Siow-Yong Lim (2003) formula as compared to Shen & Hung (1983) & Chih Ted Yang (1979) formulae. So, detailed analysis of only Shu-Qing Yang and Siow-Yong Lim (2003) formula is discussed in the present paper. Predictive capability of total STR by using fall velocity from different formulas is checked by calculating statistical parameters like Discrepancy Ratio (D.R), Mean Percentage Error, Thiel’s Coefficient of Inequality & Square of Pearson product-moment (correlation coefficient). Result analysis indicates that, Shu-Qing Yang and Siow-Yong Lim (2003) predicts STR with fair accuracy for most of the data sets when fall velocity is calculated using Zhu & Cheng (1993) formula.
