Flood Defense and Water/Sediment Management—With Particular Reference to The Yellow River - River Dynamics and Integrated River Management - page 359

(a)
(b)
Fig. 6.27 The cut off river flow and the dry river bed during the flood season in 1977: (a) A boat is resting on the bed;
(b) A floating bridge is not useful because vehicles may drive across the riverbed at any place
riverbed at any place. The river is in danger of transforming into an inland river in the foreseeable future.
Without prompt measures, China may someday find her mother river exhausted. No sediment and organic
material were transported into the sea during the dry time, which cut off the food chain for some species.
This will result in complex ecological problems, for instance, the fish in the estuary have been greatly
affected and some precious species have vanished. The river is usually regarded as an “artery” of the
country and the cut off of the river flow will seriously damage its “health”. this is sounding a warning
that water shortage is becoming a more serious problem than the need for flood control in northern
China.
6.4.4 Collapse of Spur Dykes
To stabilize the channel in the wide river valleys in the lower Yellow River many spur dykes have been
constructed. The spur dykes have, to a certain degree, fixed the channel and concentrated the flow and
cause sediment deposition between the spur dykes. The channel, therefore, was deepened and relatively
stabilized. A channelization degree is defined as the ratio of the total length of the spur dykes to the length
of the channel, or the length of spur dykes per channel length. Figure 6.28 shows the distribution of
channelization degree along the river downstream from Sanmenxia Reservoir. From the 1970s to 2002,