الفهرس 
Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Despite the advantages presented by canal coverage structures, it is critical to acknowledge that they can contribute to a notable reduction in the conveyance efficiency of canals if they become at risk of blockage. The difficulties associated with clearing debris from enclosed canals further worsen this issue. The focal point of this study is to comprehensively investigate the effects of blockage within canal coverage structures, with a specific emphasis on diverse cross-sectional shapes and varying degrees of blockage.
The research contains a comprehensive exploration involving seven cross-sectional shapes for coverage structures: the square box, circular, pipe arch, ellipse, arch, conspan arch, and a rectangular box. This assessment is carried out by combining ten different Froude numbers and an equivalent range of blockage ratios. Employing an experimental setup along with the HEC-RAS 1D numerical model, the study assesses these parameters through a series of comparative tests.
The outcomes of this study demonstrate that the presence and extent of blockage within a canal coverage structure have an adverse impact on its hydraulic performance. This negative effect is revealed through an observable increase in the head loss ratio coupled with a corresponding reduction in the velocity ratio. This decline in performance demonstrates variation across different coverage shapes, with the square box configuration showcasing the highest sensitivity to blockage. The circular section, when evaluated at the same design Froude number, follows as the second most sensitive shape to blockage.
A critical threshold surfaces in the analysis at a blockage ratio of 30%. Beyond this point, the performance of coverage structures experiences a sharp decline, signifying a critical maintenance threshold. Among the different studied shapes, the pipe arch configuration emerges as the optimum in terms of reducing the head loss. Giving similar results, a rectangular box with a height-to-width ratio of 2:3 showcases a very good performance as well.
Considering the difficulties of constructing pipe arch configurations, practical considerations favor the rectangular box shape as the most practical and efficient choice for canal coverage structure design. The insights collected from this study provide engineers and decision-makers engaged in canal management and infrastructure planning with valuable guidance for informed decision-making.