Mehdi Azhdary Moghaddam - Assistant Professor, University of Sistan and Baluchestan- Zahedan-Iran

A spillway is usually the most important appurtenant facility to a dam. The function of the spillway is to provide an efficient and safe means of conveying flood discharges to the downstream channel. The spillway design primarily depends on the design flood, dam type and location, and reservoir size and operation. Spillways can be classified based on (i) their function (main, emergency, and auxiliary), (ii) their hydraulic type (free overfall, overflow, chute, siphon, etc.), and (iii) their mode of control (ungated, and gated). While the number of new dams under construction in the world is declining, the number of existing dams that have had to be upgraded to meet current hydraulic and seismic criteria is increasing. Many failures of dams have been caused by improperly designed spillways or by spillways of insufficient capacity. Several embankment dams have been identified as unable to pass their design flows without failure due to overtopping. This study examines the hydraulics of flow on various stepped ogee-profile spillway configurations, from physical-modelling viewpoints. The main objective of the research is to investigate the hydraulic performance of several physical models having different downstream slopes and different step configurations.

discharge coefficient, stepped spillway, ogee profile