- A large dam is classified as one with a maximum height of more than 15 metres from its deepest foundation to the crest.
- A dam between 10 and 15 metres in height from its deepest foundation is also included in the classification of a large dam provided it complies with one of the following conditions :
- a) length of crest of the dam is not less than 500 metres or
- b) capacity of the reservoir formed by the dam is not less than one million cubic metres or
- c) the maximum flood discharge dealt with by the dam is not less than 2000 cubic metres per second or
- d) the dam has specially difficult foundation problems, or
- e) the dam is of unusual design
On review on consideration of “height” for arriving at whether dam is in category of Large dam or not the above definition has been retained for dams other than Earthen and Rock fill dams. For Earthen and Rock fill dams following definition of large dams has been adopted from "IS 12169-1987- criteria for design of small embankment dams" for inclusion under NRLD.
A dam exceeding 15m in height above deepest river bed level and a dam between 10 and 15 m height provided volume of earthwork exceeds 0.75 million m3 and storage exceeds 1 million m3 or the maximum flood discharge exceeds 2000 cumecs."
[Dams with height 50 m and above]