Flood Defense and Water/Sediment Management—With Particular Reference to The Yellow River - River Dynamics and Integrated River Management - page 348

There are now 3,147 reservoirs in the whole basin with a total storage capacity of 57.4 billion m 3 .
More than 4,500 water diversion projects have been completed and 29,000 pumping stations are working
for irrigation and water supply. The irrigation area has increased from 0.8 million ha in 1950 to 7 million
ha in 1995. The irrigated farmland is about 45% of the total farmland area but produces more than 70%
of the grains. In the past 50 years people have invested $5.4 billion to develop water resources for
agriculture and benefited by $57 billion in grain production, $8 billion for urban water supply, and
industries benefited by $14.6 billion.
To transport sediment is an important job of Yellow River water. It is roughly estimated that at least 20
billion m 3 are needed to transport 1 billion tons of sediment into the ocean. Figure 6.20 shows the average
runoff and sediment load along the river course in the 1950s. The runoff remained unchanged from
Huayuankou to the river mouth and the sediment load reduced slightly along the lower reaches course.
Since 1985, however, the runoff has become less and less along the course from Huayuankou to the river
mouth and the sediment carrying capacity reduces even more greatly. The reduced flow discharge is not
able to carry the same amount of sediment, and, thus, results in quick siltation of the lower reaches channel.

Fig. 6.20 Average runoff and sediment load of the Yellow River in the 1950s (after Qian and Zhou, 1964)