Final answer:
The Huang He and Chang Jiang river basins in China are heavily populated due to their fertile soils and significant agricultural output. These regions are prone to flooding but also support major cities and have historically been central to Chinese civilization.
Step-by-step explanation:
The Huang He (Yellow River), the Chang Jiang (Yangtze River), the North China Plain, and the Chang Jiang Basins are all significant geographic features of China that have historically supported large human populations. These river basins have been heavily populated due to their rich all uvial soils, which provide abundant agricultural opportunities. The Yellow River is particularly known for its loess soil, which is highly fertile, but also prone to erosion and flooding. This has led to a history of both bountiful harvests and natural disasters in the region. The Yangtze River, on the other hand, supports extensive rice and wheat farming, with major cities such as Shanghai, Wuhan, and Chongqing located along its course.
Both rivers originate from the Tibetan Plateau, receiving their water supply from heavy snowpack in the Himalayas. Their valleys frequently flood during the summer's snow melt and rainfall, depositing beneficial silt but also causing deadly floods. The significant agricultural output from these basins is a crucial reason for their dense populations, as the food production supports the sustenance and growth of civilizations.