Abstract
This paper evaluates the applicability of representative sediment size in terms of median grain size and the effective sediment sizes for the transport of non-uniform natural sediment mixtures. Natural sediment from the Krasak River, Yogjakarta was used. Bed samples were collected from three different river sections, i.e. upstream (U), midstream (M) and downstream (D). The median diameters, d <inf>50</inf> and sediment geometric standard deviation, σ <inf> g </inf> for sections U,M and D were 1.63mm, 0.91mm and 0.69mm, and 4.8, 2.3 and 1.5 respectively. Particular attention was paid to the effect of varying representative sediment sizes on the threshold sediment motion, where four threshold equations were employed. The threshold value varies when σg=4.8 and has little variation for sediment mixtures with σg<2.4. Analysis is extended to prediction of bedload transport using eight selected formulae which account for both with and without the threshold criteria of sediment motion. To account for the non-uniformity of the bed materials, a comparison between the calculated bedload discharge using d <inf>50</inf> was made with the bedload prediction when a representative sediment diameters were used. Analysis shows that an improvement of the statistical analysis was only observed for predictions calculated using Brownlie (1981) and Camenen and Larson (2005) expressions when effective sediment sizes were employed for non-uniform sediment mixtures. Employing the effective sediment sizes d <inf> e </inf> or d <inf> em </inf> to calculate the bedload discharge does not necessarily improve the bedload prediction and the use of d <inf>50</inf> is seen as sufficient.
| Original language | English |
|---|---|
| Journal | International Journal of Sediment Research |
| DOIs | |
| Publication status | Accepted/In press - 7 Oct 2013 |
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Keywords
- Bedload transport
- Non-uniform sediment
- Representative sediment size
- Threshold sediment motion
ASJC Scopus subject areas
- Stratigraphy
- Geology
Cite this
Representative sediment sizes in predicting the bed-material load for nonuniform sediments. / Wan Mohtar, Wan Hanna Melini; Junaidi, ; Sharil, Suraya; Mukhlisin, Muhammad.
In: International Journal of Sediment Research, 07.10.2013.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Representative sediment sizes in predicting the bed-material load for nonuniform sediments
AU - Wan Mohtar, Wan Hanna Melini
AU - Junaidi,
AU - Sharil, Suraya
AU - Mukhlisin, Muhammad
PY - 2013/10/7
Y1 - 2013/10/7
N2 - This paper evaluates the applicability of representative sediment size in terms of median grain size and the effective sediment sizes for the transport of non-uniform natural sediment mixtures. Natural sediment from the Krasak River, Yogjakarta was used. Bed samples were collected from three different river sections, i.e. upstream (U), midstream (M) and downstream (D). The median diameters, d 50 and sediment geometric standard deviation, σ g for sections U,M and D were 1.63mm, 0.91mm and 0.69mm, and 4.8, 2.3 and 1.5 respectively. Particular attention was paid to the effect of varying representative sediment sizes on the threshold sediment motion, where four threshold equations were employed. The threshold value varies when σg=4.8 and has little variation for sediment mixtures with σg<2.4. Analysis is extended to prediction of bedload transport using eight selected formulae which account for both with and without the threshold criteria of sediment motion. To account for the non-uniformity of the bed materials, a comparison between the calculated bedload discharge using d 50 was made with the bedload prediction when a representative sediment diameters were used. Analysis shows that an improvement of the statistical analysis was only observed for predictions calculated using Brownlie (1981) and Camenen and Larson (2005) expressions when effective sediment sizes were employed for non-uniform sediment mixtures. Employing the effective sediment sizes d e or d em to calculate the bedload discharge does not necessarily improve the bedload prediction and the use of d 50 is seen as sufficient.
AB - This paper evaluates the applicability of representative sediment size in terms of median grain size and the effective sediment sizes for the transport of non-uniform natural sediment mixtures. Natural sediment from the Krasak River, Yogjakarta was used. Bed samples were collected from three different river sections, i.e. upstream (U), midstream (M) and downstream (D). The median diameters, d 50 and sediment geometric standard deviation, σ g for sections U,M and D were 1.63mm, 0.91mm and 0.69mm, and 4.8, 2.3 and 1.5 respectively. Particular attention was paid to the effect of varying representative sediment sizes on the threshold sediment motion, where four threshold equations were employed. The threshold value varies when σg=4.8 and has little variation for sediment mixtures with σg<2.4. Analysis is extended to prediction of bedload transport using eight selected formulae which account for both with and without the threshold criteria of sediment motion. To account for the non-uniformity of the bed materials, a comparison between the calculated bedload discharge using d 50 was made with the bedload prediction when a representative sediment diameters were used. Analysis shows that an improvement of the statistical analysis was only observed for predictions calculated using Brownlie (1981) and Camenen and Larson (2005) expressions when effective sediment sizes were employed for non-uniform sediment mixtures. Employing the effective sediment sizes d e or d em to calculate the bedload discharge does not necessarily improve the bedload prediction and the use of d 50 is seen as sufficient.
KW - Bedload transport
KW - Non-uniform sediment
KW - Representative sediment size
KW - Threshold sediment motion
UR - http://www.scopus.com/inward/record.url?scp=84938613939&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84938613939&partnerID=8YFLogxK
U2 - 10.1016/j.ijsrc.2014.09.002
DO - 10.1016/j.ijsrc.2014.09.002
M3 - Article
AN - SCOPUS:84938613939
JO - International Journal of Sediment Research
JF - International Journal of Sediment Research
SN - 1001-6279
ER -