In this research, physical models of the piano key weirs with different
geometrical  specifications  are  made  using  PVC  plates.  Experiments
have  been  conducted  under  different  hydraulic  conditions  in  order  to
determine the flow behavior, discharge coefficient, discharge reduction
and  total  head  ratio  curves  under  the  free  and  submerged  flow
conditions. A one meter width channel is used for experiments and flow
rate  is  measured  using  an  electromagnetic  flow  meter  with 1  lit/s
accuracy. Three dimensional water surface profiles are measured using
a digital point gauge with 0.01 mm accuracy. Furthermore, flow over a
one meter width linear sharp crested weir is investigated to assess the
hydraulic  performance  of  the  tested  piano  key  weirs  with  the
corresponding hydraulic conditions. Results have shown that hydraulic
behavior of the submerged piano key spillways depends on the height.
By increasing the weir height, the submergence threshold decreases and
the  rate  of  the  discharge  reduction  increases.  Practical  equations  are
developed to determine the  discharge  coefficient, discharge  reduction
factor  and  non-dimensional  total  head  curves under  submerged  flow
condition.