The Sudden-happening Catastrophic Flood-Unavoidable Problem in Flood Control of the Yellow River

摘要

The sudden-happening catastrophic flood in disaster chain has the following basic features; ① Having direct causation or is congenetic in cause of formation, constituting concurrent disaster chain; ② The sequential calamity of a gross disaster, with long duration and big harmfulness; ③ Strong suddenness and great difficulty in preventing. Many natural calamities, especially those calamities of higher grade and larger intensity, usually induce a series of secondary disasters, which is called disaster chain. For example, 7.7 Magnitude, 7.8 Magnitude and 8.5 Magnitude earthquakes have hit Chile continuously on May 22, 1960, which have induced the 3,000,000 m3, 6,000,000 m3 and 30,000,000 m3 landslips in Ranihe lake area. The Lower Yellow River is complex in configuration and the river regime is wandering and changeable. The " secondary suspended river" is severe and the Yellow River has been breached repeatedly in history. Though the lower Yellow River dykes have been solidified and maintained for many years, there are still some hidden dangers, and dangerous factors such as inundating or "rolling river", flood discharge along the dykes or breaching and so on which cannot be eliminated thoroughly. Thus the control of catastrophic flood in disaster chain has become an unavoidable problem for the flood control of the Yellow River.