الفهرس 
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Abstract
Weirs are one of the most important heading up structures.
In fact, they are used in many applications such as reducing
the water slope in canals, water distribution, and measurement
of discharge. The present study aims to improve the weir
characteristics by optimizing its geometric properties.
Actually, the main purpose is to propose solutions to the weir
’problems by allowing the passage of more discharge through
its body in order to avoid the sedimentation problems in
upstream side. The combination between perforated weir and
gates was experimentally studied. The experimental studies
were done on wooden model of 21 cm height and 2cm crest
width. In addition, the study was investigated in seven stages.
The first stage studied the effect of changing the angle of
the weir back angle as 90°, 60°, 30°, and 15° on the flow
characteristics. In the second stage, six models of a perforated
weir were studied with different slot diameters in the center
point. The Different slot diameters were (1, 1.25, 1.5,2, 3 and
4 inch). In the third and fourth stages, the effect of varying the
vertical location of the slot and its number on the flow
characteristics were investigated. The different heights for the
vertical locations were 0.25, 0.5 and 0.75 of the weir height.
The number of the slots used included, one, two and three