Flood Defense and Water/Sediment Management—With Particular Reference to The Yellow River - River Dynamics and Integrated River Management - page 364

Fig. 6.34 Nodal avulsions and the abandoned Yellow River channels. The coastlines show the land created by the river
in the periods between 1855-1972, 1972-1976, and 1976-1996
On average the delta channel changed once per 10 years. Before the 1950's, the change in the river
course was triggered by overflow and levee breach at the diversion point. Since 1953, the river course
has been artificially shifted 4 times. In the spring of 1964, an ice jam occurred and the safety of the
Shengli Oil Field in the delta was threatened. The levee at Luo-jia-wu-zi was artificially broken, and the
river shifted from the Shen-xian-gou channel to the Diao-kou-he channel. Before the recent diversion in
1976, people dug the Qing-shui-gou channel at a cost of $1 million. In May 1976, the river course was
artificially shifted to the Qing-shui-gou and since then this river channel was safely used for more than
30 years (plus the Qing-shui-gou Channel period). During this period the river created land at a rate of
20-40 km 2 /year. It follows the routine of “channel siltation—high flood—broken levee—channel shift
creation of new land.”
In the early Qing-shui-gou period, the river channel was not well shaped. The sediment-laden flow
built up its channel by depositing sediment in low velocity areas and scouring sediment in high velocity
areas. During this process, seasonal variation of discharge and sediment deposition in the delta area has
resulted in a high frequency of mouth migration, as shown in Fig. 6.35 (Ji et al . , 1994). In the first 3 years
(1976-1979), the channel was unstable and the new river mouth wandered in an area of a range of 30 km.
The main stream flowed eastward into the sea in October 1977, but changed northward in October 1978.
In the flood season of 1979 the river mouth moved from northeast to southeast again. The frequent shift
of the mouth and channel is due to the floods with sediment high concentration in these years with a
maximum sediment concentration up to 240 kg/m 3 . Since 1980, the main channel has moved east again
and a relatively stable meandering channel formed. In 1986 the local people extended the guiding levees
and the channel upstream from Q8 was not allowed to wander anymore (Fig. 6.35).