Fifteen-stage operation of gated spillways for flood routing management through artificial reservoirs

Abstract

A procedure to identify sets of operational rules for gated spillways for optimal flood routing management of artificial reservoirs is proposed. The flood retention storage of a dam having a gated flood spillway is divided into 15 sub-storages whose surface elevations are identified as critical levels. The most suitable operation set for the downstream conditions and for the dam can be chosen from many derived operation sets. The spillway gates are operated in an optimum way for any floods from very small magnitudes to the probable maximum flood (PMF), without having to forecast the actual magnitude of the incoming flood hydrograph. Decision floods are formed by dividing the PMF into 15 sub-hydrographs by 5 and 10% increments in the ranges 5-50% and 50-100% of the PMF, respectively. Many potential spillway gate openings from closed to fully open are chosen initially. As a result of a series of routing simulations of 15 decision floods, a set of 15 gate openings is determined such that all floods from very small magnitudes to the PMF may be routed without overtopping the dam crest. Next, a few more 15-stage operation rules are determined such that the gate openings of the initial stages are decreased as their critical levels are increased stepwise, with the objective of attenuating smaller floods more effectively and releasing higher outflows for larger floods close to and including the PMF. The developed model is applied to the Catalan and Aslantas dams in Turkey, both of which serve for flood mitigation as well as hydropower generation. Manoeuvre à quinze niveaux de déversoirs à vannes pour la gestion du transfert de crues au travers de réservoirs artificielsRésumé On propose une procédure pour identifier des ensembles de règles opérationnelles de déversoirs à vannes pour la gestion du transfert des crues dans des réservoirs artificiels. Le volume de rétention des crues d'un barrage ayant un évacuateur de crues à vannes est divisé en 15 sous-stockages dont les niveaux sont identifiés comme des niveaux critiques. L'ensemble de manoeuvres le plus approprié pour les conditions en aval et pour le barrage peut être choisi parmi de nombreux jeux de manoeuvres possibles. Les vannes de l'évacuateur sont manoeuvrées de manière optimale pour toute crue, allant d'une crue de très petite amplitude à la crue maximale probable (CMP), sans avoir à prévoir l'ampleur réelle de l'hydrogramme de crue entrant. Les crues de décision sont produites en divisant la CMP en 15 sous-hydrogrammes par incréments de 5 et 10% dans les gammes de 5-50% et 50-100% de la CMP, respectivement. De nombreuses ouvertures potentielles de vannes du déversoir, de la position fermée à complètement ouverte, sont choisies au départ. Résultat d'une série de simulations du transfert de 15 crues de décision, un ensemble de 15 ouvertures de vannes est déterminé, de telle sorte qu'elles puissent transférer toutes les crues, depuis les crues de très petite amplitude à la CMP, sans débordement au-dessus de la crête du barrage. Ensuite, quelques règles de manoeuvre...

Exploitation of Documented Historical Floods for Achieving Better Flood Defense

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Assessment of water resources system resilience under hazardous events using system dynamic approach and artificial neural networks

“…Earthquakes commonly trigger landslides producing consequences ranging from small soil cover failures to devastating rock avalanches (Fan et al 2019). As a part of a water system, a large dam can fail under severe seismic conditions leading to uncontrolled release from the system, and require optimal operational rules for gated spillways (Haktanir et al 2013). Moreover, a water resources system located within a high seismic area possesses a substantial risk for the downstream river sections since active faults may cause damaging deformation of the embankment leading to uncontrolled water system behavior (Tosun 2015).…”