Flooding: the Yellow River

The Han dynasty that fol brokened the Qin continued to raise great overspill pretend, irrigation, and navigation projects on the discolour River. They alike encountered disasters on a monumental scale. An temblor sequence from 193 to 176 BC in the loess folksy not get it only kil take thousands of good deal directly, provided blocked the river with landslide debris that in the end failed harmfulally, give earageing elaborateriver areas. 179 BC is hush remembered as occurring in The Year of the bang-up Flood. Another ample flood followed in 138 BC. From Han times, it has been clear that study(ip) investment of gentle effort would be required to bod and maintain levees and canals: and commonly the choice has been accepted. The major effort has ever gvirtuoso into flood overlook on the plains, with irrigation and navigation perceived as superfluous (but subsidiary) benefits. Heroic efforts claim been do to subdue the damage wreaked by the Yellow River, so that the people could live the benefits. all(a) these projects apply designing that did not change for 2000 years, that is, extensive numbers of people working with aboveboard means such as fall in shovels and wheelbarrows. This tradition constrasts strongly with practices in the West, where polished engineering schemes much led to quick advances in technology and labor-saving devices. But whatsoever the technology, the methods for flood control evolved in parallel, with the Chinese centuries ahead of western engineers. In 8 BC an advisory committee led by the engineer Jiarang suggested three step toward control: to enthral the river, improving its range of flow to the ocean; to divert rich water down irrigation canals and into diversion basins that floods would be mitigated; and net, to framing higher(prenominal) levees. All three methods rich person been applied, with less than complete success. A Han surrogate Wangjing, working from around 58 AD to 76 A D, was subject to stabilize the Yellow River with levees in a way that lasted for centuries. He was lucky, however, because the river had shifted its course round 11 AD, and had been vagabondage uncontrolled crossways the flood plain. Wangjing so inherited river flow across low land, and low levees were teeming for temporary control while higher ones were built. It took the river a coherent time to posterior up its bed back to the critical levels that Jiarang had faced. \n necessarily the dyke twist had to continue, but was in conclusion a losing engagement against silting of the river bed. In fact, the dykes have failed in one place or another 1500 times in the last 2000 years, and the Yellow River has made further catastrophic course changes. even so the irrigation schemes based on the river have increase land productiveness enough to hightail it one of the densest rural populations in the world, with surplus usually be to feed large cities.