34
Tecnología y Ciencias del Agua
, vol. VIII, núm. 2, marzo-abril de 2017, pp. 31-41
Li
et al
.,
Particle size distribution and settling velocity of sediments in water diverted from the Yellow River during border-strip irrigation
•
ISSN 2007-2422
technique. Figure 1 illustrates the layout of the
experimental field. Before the experiment, the
slope of the field along the strip length was
measured using a leveling instrument, and the
average slope was calculated to be 1/1000.
Experimental methods
After the preliminary work was complete, water
diverted from the Yellow River was applied to
the field on June 19 and July 30, and relevant
experimental parameters were determined. The
rate of inflow was measured using a Parshall
flume. The bottom of the Parshall flume were
covered with sediments, which was swept by
a broom, and rinsed off thoroughly with water
when the irrigation event was done. Specific
parameters and methods used in the experiment
are as follows:
1. During the experiment, marker posts were
set up along the length of the strips at
intervals of 10 m. The time required for ir-
rigation water to cover the majority of the
surface around each post was recorded using
a stopwatch, in order to determine advance
time.
2. Monitoring points were designated along
the length of each strip at intervals of 40 m.
Three Trime tubes were embedded in the soil
at each point to monitor variations in soil
water content within the soil profiles (see
figure 1). Soil samples were collected two
days before irrigation, and two days and
five days after irrigation. Then time-domain
reflectometry (TDR) was used to determine
the volumetric water content within the soil
profiles at the monitoring points at depths
from 10 to 100 cm. The TDR was calibrated
Figure 1. Layout of the experimental field.
Table 2. Composition of the sediment in the Yellow River water.
Percentages of particle size ranges
Median
particle
size
(mm)
Average
particle
size
(mm)
Sediment
concentration
(kg/m
3
)
Particle size
(mm)
<
0.125
<
0.062
<
0.031
<
0.016
<
0.008
<
0.004
<
0.002
<
0.001
0.009
0.015
1.567
Percentage
(%)
100.0 98.1 86.3 68.2 46.9 27.5 13.6 5.6
