Wikipedia
Suranga
Suranga (also Surangam or thurangam) (English: Tunnel well) is a traditional water management system used to provide a reliable supply of water for human settlements and irrigation in Kasargod district of Kerala and Dakshin Kannada district of Karnataka, India. A suranga is basically a horizontal tunnel dug in the slope of a laterite hill for about to , which uses gravitational force for extraction of the underground water and collect into a storage tank. As both the areas are covered by uneven and steep laterite hill which makes boring of traditional bore well hard and expensive, surangas are considered as a relatively cheap option.