The Yangzi River flood was worse than it should have been due to de-foresting, etc., and was nearly catastrophic. 150,000 soldiers were sent in to sandbag the river. There were 7 peaks, with the sixth being the highest (although the seventh was close). At times, they were considering sacrificing certain cites to divert some of the water and protect the other cities, but the dams held.
In the north, the flood of Song Hua Jiang wasn't as bad (it occurred on a shorter stretch of river), but it flooded one of China's main oil fields. The oil pumps were 1/3 under water, but continued to pump oil. The biggest problem here was that it was much colder (so those human dikes wouldn't work...).
The flooding lasted about two months. By the time we were leaving, water levels were dropping and things were under control. Jiang Zemin was quick to pounce on the event as an internal propaganda opportunity to consolidate his power, claiming that the successful flood control showed how well things were working: The Central Government issued a well thought out plan, and the people in the field successfully executed the plan. Of course, Jiang Zemin didn't mention that the Chinese government acknowledges that it was deforestation (presumably also under the Central Governments control) that caused the severity of the flood...
The damage must be incredible. Millions of people were affected, lots of farmland ruined, and the threats of disease and food shortages loom. And the threat of flooding remains for future years. They are building a dam on the Yangzi, but dams can only do so much, and are half the problem anyway.
When we were planning our trip, most people suggested (and some pressured us!) going to Three Gorges. Had we made plans to go there, we would have had to change those plans, since no one (except for 150,000 soldiers) went to the area. Given that the river always floods in the summer, you should plan your trip accordingly. China Index