Comment: 12:12 - 13:14 (01:02)
Source: Annenberg/CPB Resources - Earth Revealed - 19. Running Water I: Rivers, Erosion and Deposition
Keywords: "James Sadd", meander, flood, floodplain, flatland, river, "river channel", riverbank, bank, landscape, humans, Tigris, Eurphrates, Mesopotamia, Yangtze, "Huang Ho", China, Nile, Egypt, crop, "muddy sediment", nutrient, deposition, irrigation, "geologic hazard", agriculture
Our transcription: Shifting meanders and repeated flooding along rivers produce broad flatlands called "floodplains."
When a river goes into flood, the water level in the river channel rises until water spills over the riverbank, drowning the adjacent landscape and giving the floodplain its name.
Human population centers have historically been closely linked to the flood plains of major rivers: like the Tigris and Euphrates in ancient Mesopotamia, the Yangtze and Huang Ho in China, and the Nile in Egypt.
Flood plains are good places to grow crops because as each flood inundates the plain, it carries with it a muddy sediment rich in organic matter and nutrients.
The sediment is deposited in flat layers atop the flood plain and is naturally irrigated by the floodwaters.
But life on the floodplain is a double edged sword.
The agriculture benefits of these periodic floods are offset by damage to homes and cities, and in some cases, to the people who inhabit them.
Geology School Keywords