the.com/cofferdam
a wall that politely asks a river to leave so engineers can work dry
means A temporary watertight enclosure built in a river, lake, or seabed and pumped dry so workers can construct or repair bridge piers, dams, and other foundations on the now-exposed bottom.
from A workmanlike compound of "coffer" and "dam." "Coffer" comes through Old French "cofre" (a chest or strongbox) from Latin "cophinus," a basket or hamper — the same root that gives us "coffin." By the 17th century English used "coffer" for any boxlike enclosure, and engineers naturally welded it to "dam" (a Germanic word for a water-barrier, cousin to Dutch and German "dam") to name a box that holds water out rather than holding treasure in.
- function
- creates dry workspace inside open water
- hoover dam
- two cofferdams diverted the entire colorado river
- naval use
- empty void spaces protect ships from fuel leaks
- name origin
- coffer once meant strongbox or watertight chest
- failure risk
- sudden flooding can drown workers instantly
three gorges dam cofferdam — china's yangtze river, 1997-2002, largest cofferdam ever built to construct the world's biggest dam
itaipu dam cofferdam — brazil-paraguay border, 1970s, massive structure holding back paraná river during dam construction