Sediment Movement in Alluvial Rivers - River Dynamics and Integrated River Management - page 291

Table 5.1 Average monthly sediment concentration and maximum-recorded sediment concentration of ten main
tributaries of the Yellow River

Period of
record

Annual
load (10 6 t)

River Gauging station Statistic June July August Sept

S av 411 523 369 216

64.1

Huangfuchuan Huangfu 1953-1979

S max 1,370 1,570 1,480 1,240

S av 327 410 373 178

27.8

Gushanchuan Gaoshiya 1953-1979

S max 1,300 1,190 1,090 829

S av 162 405 319 90.6

135

Kuye Wenjiachuan 1953-1979

S max 1,400 1,700 1,500 970

S av 12.5 352 323 90.8

106

Wuding Baijiachuan 1956-1979

S max 1,290 1,270 1,180 958

S av 384 503 448 105

45.3

Qingjian Yanchuan 1954-1979

S max 1,150 1,080 970 881

S av 287 454 368 119

54.6

Yanshui Ganguyi 1952-1979

S max 1,200 1,190 1,033 1,070

S av 19 43 59.4 37.6

43.8

Fenhe Hejin 1943-1979

S max 174 386 227 143

S av 37.1 71.4 80.2 28.5

168

Weihe Xianyang 1934-1979

S max 654 588 729 662

S av 168 349 329 110

286

Jinghe Zhangjiashan 1931-1979

S max 906 1,430 984 946

S av 121 337 287 58.1

96.8

North Luohe Zhuangtou 1933-1979 S max 987 1,150 1,190 1,340
S av average monthly sediment concentration in kg/m 3 ; S max maximum recorded sediment concentration in that
month in kg/m 3

A hyperconcentrated flow is non-Newtonian if the sediment consists of a certain amount of clay
particles. The rheological curve of the hyperconcentrated flow approximately follows the following
constitution equation (Bingham model):

d
d

u
y

WWK (5.53)

B

where W is the yield stress, and K is the rigidity coefficient.
Fine sediment in the flow can be supported by the yield stress and transported for long distance
without deposition and exchange with the bed material. In such a case the concept of “sediment-carrying
capacity” is meaningless. The amount of sediment transported by the flow depends only on the incoming
sediment amount and boundary resistance. Dynamic characteristics of the flow depend on the rheological
properties of the mixture, which in turn depend on the content of clay and silt.
Hyperconcentrated flow is often laminar because of its high viscosity. In the upper central part of an
open channel flow where the shear stress is less than the yield stress, there is no velocity gradient. The
mixture there moves entirely at a uniform velocity u p and forms a flow plug. In wide and shallow rivers
the velocity of the plug u p and the plug zone are given by
2

§ ·

J J W W

u

m

h

B

, h

B

y h (5.54)

¨ ¸ p

2 K J J J J

© ¹

m m