A ditch was a type of landform that was used to channel water; often alongside roadways or fields.
Kathryn Janeway's father used to call the Grand Canyon "Earth's biggest ditch". (VOY: "Imperfection")
During her brief service on Starbase 80 in 2381, Beckett Mariner fell into an open ditch, making her paranoid when the USS Cerritos was forced to visit the starbase, and she was thus forced to reboard, the following year. (LD: "Starbase 80?!")