| Summary: | By the time the water flowing in the river, a number of basic sediment
(bed load) and fine (suspended load) carried with the flow. At the time the river
flow is hampered due to weir the flow rate of the river bottom will be reduced,
and the ability of water to carry sediment flow will be reduced as well, it leads to
the deposition of sediment.The sediments will continue to increase up to the weir
crest. Sediment deposition resulting in reduced counting weir height, it causes
changes in the water level upstream of the weir, which high impact on changing
the energy of water flowing over the weir. These changes result in changes in the
energy difference between the high-energy water upstream with downstream weir.
Stream flowing on the surface of the sloping weir in the supercritical state, while
the flow conditions downstream of the weir is subcritical. Flow changes from
supercritical to subcritical cause hydraulic jump (Raju, 1986). As a result of the
hydraulic jump is often cause the waves or eddies (vortex) which can cause
scouring at the base of the channel. It is therefore necessary to study the
relationship between changes in high-energy (head) due to sedimentation in the
weir upstream and downstream weir scour occurring.
The research was conducted in the laboratory of civil engineering
hydraulics using an open channel (flume) equipped with hydraulic circuits, doors
and measuring tools. Theory for flow using criteria that had been developed in
Irrigation Planning Standards - Building Planning Criteria KP-02, by the Public
Works Departmen based on data from the United State Bureau of Reclamation
(USBR), the United State Army Corps of Engineers. Local scoure theory using
empirical equations that have been studied previously as Schoklitsch (1932),
Veronese (1937), Jaeger (1939), Catakii (1973).
Results from the research showed that the increasing sedimentation in the
upstream weir resulted
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