Nullah

A nullah or nala (Hindustani or "nallah" in Punjabi) is an 'arm of the sea', stream, or watercourse, a steep narrow valley.

During occasional heavy rains, torrents rush down the nullahs and quickly disappear.

Encroachment into nullahs is a significant problem in many South Asian cities, since it hampers the drainage of stormwater and can exacerbate floods.

[1][2][3] In East Asia, a nullah (Chinese: 明渠; pinyin: míngqú; Wade–Giles: ming2-chʻü2; Jyutping: ming4 keoi4; lit.

'open ditch') refers to an open, usually concrete-lined flood control channel designed to allow rapid drainage of stormwater or a sewerage channel for industrial wastewater from high ground, to prevent flooding or stagnation in urbanised coastal areas,[4] and basically is an often dry canal used as a reserve drain.