Water Discharge and Total Suspended Sediment Dynamic in
the Lower Mekong River at Kratie and Chroy Changvar
Figure 2 shows the hydrographs of the daily water discharge and
observed total suspended sediment concentrations (TSS) at Kratie from
1995 to 2018 and Chroy Changvar from 1993 to 2017. The daily water
discharge clearly reflects the annual dry and rainy seasons, with low
flows in March and April (down to approximately 2,000
m3/s), followed by onset of the rainy season and
increased discharges in May, and high flows in August and September (up
to approximately 30,000 m3/s). At Kratie, the maximum
discharge reached 58,205 m3/s in the rainy season of
1996 while the minimum discharge was 1,073 m3/s in the
dry season of 1995. At Chroy Changvar station, maximum discharge reached
40,556 m3/s in the rainy season of 2014, while minimum
lowest discharge was 405 m3/s in the dry season of
1995.
We calculated descriptive statistics such as minimum, maximum, mean, and
standard deviation to show tendency and variation of water quality
parameters to illustrate the temporal distribution of important basic
water quality parameters and for highlighting the specific
characteristics. Additionally, we calculated skewness and kurtosis to
determine if the data were skewed with positive or negative tails, and
to determine the peakedness of the distributions, respectively. The
summary statistics of TSS concentrations from 1993-2017 at Kratie and
Chroy Changvar are summarized in Table 4 . Between June and
October, water in the Mekong River was opaque, with TSS concentrations
from 90 to 200 mg/l as it carried sediments derived from erosion across
the land surface. On the falling limb beginning in December, the TSS
concentration drop to less than 20 mg/l on average. Figure 3illustrated the rating curve of observing water discharge and daily
water discharge and observed total suspended sediment concentrations
(TSS) at Kratie and Chroy Changvar station (1993 to 2017). Discharge and
TSS concentrations showed significant statistical relations, with
R2=0.53 for Kratie station and
R2=0.65 for Chroy Changvar.