The only provision among the following which can help control the seepage through the body of an earthen dam and thus to keep the phreatic line well within the dam width is _________________
(a) upstream impervious cut-off
(b) drain trench along the downstream toe
(c) relief wells
(d) chimney drain
The question was asked in a job interview.
This is a very interesting question from Rock Fill Dams in section Earthen and Rock Fill Dams of Irrigation Engineering