Waru Warn or Waru Waru is an agricultural technique developed by pre Hispanic peoples in the Andes region of South America, from Colombia to Bolivia. It is dated around 300 B.C.
The technique has been revived in 1984, in Tiawanaco, Bolivia, and Puno, Peru.
The technique consists in combining raised beds with irrigation channels so as to prevent damage due to soil erosion during floods. The technique ensures both collecting of water (either fluvial water, rainwater or phreatic water) and subsequent drainage. The drainage aspect makes it particularly interesting for many areas subjected to risks of brutal floods, such as tropical parts of Bolivia and Peru where it emerged. Waru waru has been used in many countries like China.