2-D numerical models - Computational River Dynamics - page 267

Case 2. Sediment transport in the lower Yellow River

Wu et al . (2006) simulated the flow and sediment transport in the lower Yellow River
during the 1982 flood using the flow model in Section 6.1.3.1 and the semi-coupled
sediment model in Section 6.2.3. The computational domain was the 103 km long
reach between the Huayuankou and Jiahetan gauge stations. The Huayuankou sta-
tion, located 259 km downstream of the Sanmenxia Hydroproject, was set as the inlet.
The computational mesh is shown in Fig. 6.8, and consists of 201 and 21 points in the
longitudinal and transverse directions, respectively. The measured time series of flow
discharge and sediment concentration at Huayuankou, shown in Fig. 6.9(a), were
used as inflow boundary conditions, while the measured time series of water stage
at Jiahetan was used as the outlet boundary condition. The peak flow discharge of
this flood at Huayuankou was 15,300m 3 s − 1 , while the peak sediment concentration
was 66.6 kg m − 3 . The sediment was non-uniform, with sizes ranging from 0.002 to

0.18mm. Five size classes were used to represent the non-uniform sediment mixture.
The Manning roughness coefficient was between 0.009 and 0.015, with bigger values
for the rising stage and smaller values for the falling stage of the flood. The compu-
tational period was from July 30 to August 11, 1982. The time step was 15 minutes.
The adaptation coefficient

·

was 0.25. The effect of sediment concentration was
considered by modifying the settling velocity of sediment particles according to the
Richardson-Zaki formula (3.19).
Fig. 6.9(b) shows the measured and simulated flow discharges and sediment con-
centrations at Jiahetan (outlet). The simulated results generally agree well with the

α

Figure 6.8 Computational mesh between Huayuankou and Jiahetan.

Figure 6.9 Flow discharges and sediment concentrations at (a) Huayuankou (inlet) and
(b) Jiahetan (outlet) (Wu et al ., 2006).