The thickness or width of a dam at the level of the top (crest) of the dam. In general, the term "thickness" is used for Gravity and Arch Dams and the term "width" is used for other dams.
CREST WIDTH (OR TOP THICKNESS)
Meaning of CREST WIDTH (OR TOP THICKNESS) in English
Environmental engineering English vocabulary. Английский словарь экологического инжиниринга. 2012