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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Comparative study of original ackers & white relation along with modified
Comparative study of original ackers & white relation along with modified
Author : S. I. WAIKHOM1, DR. S. M. YADAV2
ABSTRACT
Reliable and quantitative estimates of sediment transport are very important in river engineering and water management
projects. Numerous comparison studies, by researchers like Nakato T, Wu et al. and others, have been conducted on
sediment transport using various total load formulas for wide range of flume and field data. Most of these studies
conclude that Ackers & White relation is quite reliable and a good predictor. In light of this outcome, an analysis was
done using this relation for the flume data set of Samaga et al, Soni J P and river data of Tofalleti F.B , with an aim to
verify the validity of result for Indian terrain envisaging further test and applicability of the Ackers & White relation.
Comparison was also done with Ackers & White relation incorporating modified coefficient. The performance of the
selected sediment formula was tested on the basis of accuracy in predicting the observed sediment within a certain
discrepancy ratio. Statistical analysis and graphical comparison are utilized to demonstrate the performance and
variations for different data sets. Overall, original Acker & White function under predicts, with percentage error ranging
from -20% to -90 %, for all the selected data sets. The evaluation revealed that, for all four mixtures (of Samaga et al
data set), prediction of sediment load is superior in comparison to other data sets. It was also observed that both Acker
& White (1973) and Acker & White (1990) function gives better value for d35 as representative size of the bed material
instead of d50 in Samaga et.al data set. It was also noted that the result predicted by both selected transport function has
little difference for d50 ranging from 0.24 mm to 0.35 mm in almost all chosen data sets. Analysis of the result also
conclude that Ackers and White (1973) function changes its trend from under prediction to over prediction as the
diameter decreases but interestingly, predictions with the modified parameters (Ackers and White,1990) deviate
significantly from that of the original formula, except for a very few cases for sediment diameter less than 0.18 mm as
unpredictable trend is observed in Ackers and White (1990) approach. When the diameter decreases it over predicts but
again in some cases it under predicts to high degree of deviation so diameter of sediment alone cannot judge the trend
of prediction which was observed in the prediction of transport rate using Tofalleti .F.B.data set.
File Size : 777,179 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 18/08/2015
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