An
overflow spillway
is most often constructed as part of a gravity
dam or a buttress
dam. The spillway section is lower than the other
sections of the dam allowing water to flow over its top and
down its front face.
Water flowing
over spillway of
Booth Wood concrete
gravity
dam in Yorkshire, England
Sometimes,
the whole of the dam acts as an overflow spillway.
Water cascading
down the
overflow spillway of Caban
Coch Dam in Mid-Wales
A
close up of the spillway when it is dry shows that the top and
downstream
face are curved to control the flow of water over it.
