الفهرس 
CHAPTER [1]: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The present experimental study was carried out, to examine the effects of the
different blocking ratios upstream the coverage on the hydraulic efficiency of open
channels. Previous studies were carried out to cope with this problem in different
aspects. They considered the variations in the discharge capacity and heading up resulted
from presence of the coverage. Few studies were investigated the impact of blockage
ratios upstream the coverage on the hydraulic efficiency of open channels (water depth,
heading up, velocity and downstream scour parameters). So, it is intended, in this
experimental research, the effect of blocking ratios at the inlet of coverage on the
hydraulic efficiency of open channels.
The main objectives of this study were to determine the effect of cover part of
watercourse by two unsuitable cross sections design of coverage on theses watercourse.
Also to study the effect of different blocking ratios on the hydraulic characteristics of
the watercourse. Also to determine the difference between the performance of both
circular-section and box-section. In order to achieve this. A proposed dimension analysis
and an experimental works were developed.
All experiments were conducted in the Laboratory of Irrigation and Hydraulics at
the Channel Maintenance Research Institute (CMRI), affiliated to the National Water
Research Center (NWRC). Number of scenarios with different discharges in case of
different blocking ratios were tested.
The water surface profiles, water velocity profiles and pilot area of scour for each
scenario were examined and recorded. Scenarios of different blocking ratios were
conducted and the results were analyzed in some details. Based on this analysis, The
characteristics effect of box-sec on term of maximum scour length divided on upstream
water depth (Ls/yu) was less than circular-sec with average value ≈25%, that mean the
best section in designing coverages was Box-section.