KAJIAN LOKASI PENGAMBILAN SAMPEL SEDIMEN SUSPENSI ARAH TRANSVERSAL TERHADAP NILAI KONSENTRASI SEDIMEN SUSPENSI RATA-RATA TAMPANG (Perbandingan Data Pengukuran Laboratorium dan Lapangan)
ABSTRACT: Sampling of
suspended sediment in the field is often conducted not in accordance with the appropriate
sampling standards due to many constraints found in the field. Theoretically,
sampling of suspended sediment should be taken in the whole
flow-cross section, from
the left to
the right side
of channel, and from
the bottom to the free
water surface. However, due
to constraints found
in the field,
sampling of suspended
sediments are often
only taken at
certain (transversal) positions of the channel. This will lead to
inaccuracies in the prediction of suspended sediment discharge. This article
analyzes how the sediment concentration taken in certain transversal positions
of the channel relate to their cross-sections averaged values, either for data
obtained in the laboratory, and for data obtained in the field. 125 profiles of suspended
sediment concentration of
laboratory data − measured
in the flume
at 5 different positions
in transversal direction − , and
50 profiles of
field data − measured
in Mataram irrigation
channel at 5 different positions −
are analyzed in this article, in which, for each flow run, the depth
averaged of and the cross-section averaged of suspended sediment concentrations are
calculated and compared.
The findings of
the data analyzed
in this article
show that the nearer to the wall, the suspended
sediment concentration, yC / C , tend to decrease, whereas the nearer to the
center of the channel, yC / C , tend to
increase. The values of , yC / C , of
the field data are found to be smaller than the ones of laboratory data, that
is for the data near to the wall; whereas to be larger in the center of the
channel. Although the trend curves of yC / C
for the laboratory and the field data are relatively difference, however
the positions where, yC / C , = 1, are almost
the same, i.e.,
at z/B 0,2.
This results mean
that the cross-section
averaged of suspended
sediment concentration can be obtained from the sampling of
suspended sediment concentration at a point of
z 0.20 B, where B is the channel width.
Keywords: sediment sampling
locations, sediment concentration distributions, depth and cross-section
averaged suspended sediment concentrations
Penulis: Bambang Agus Kironoto
Kode Jurnal: jptsipildd070010
