Question

A phreatic line in seepage analysis is defined as the line on which pressure is _______________

(a) equal to the atmosphere

(b) greater than atmosphere

(c) lower than atmosphere

(d) varying

I had been asked this question by my college professor while I was bunking the class.

Asked question is from Design Criteria of Earth Dams in chapter Earthen and Rock Fill Dams of Irrigation Engineering

Answer 1

The correct choice is (a) equal to the atmosphere

To explain: The line which joins the points in a dam section at which pressure is equal to the atmospheric pressure is called phreatic line. It is also called as line of seepage or saturation line. There is capillary fringe i.e zone of capillary which has negative hydrostatic pressure above this line.