The Yangtze River runs through southern China, one of the most populated areas on Earth. The region’s people, most of whom lived at subsistence level, depended on the river for water for their personal and farming needs. In April, the river-basin area received far-above-average rainfall. When torrential rains came again in July, the stage was set for disaster. The Yangtze flooded over a 500-square-mile area. The rising waters drove 500,000 people from their homes by the beginning of August.