In reading up on potagers and raised beds at wikipedia, I came across a reference to something called a “waru waru” or “waru warn”. This turns out to be an ancient South American agricultural system of using canals between raised beds. These serve several purposes: preventing damage from sudden heavy rainfalls, keeping moisture levels in the beds even, improving the quality of poor soils, and preventing frosts. Some(unfortunately dry) reading on the subject can be found here.
Looking about a bit more, I found this fantastic site about various South American agricultural anti-frost practices, including some amazing circular terraced fields in Ecuador.