Entrapment of driftwood at ogee crested spillways with piers : influence of woody debris characteristics on blocking probabilities

Furlan, Paloma (EPFL, Lausanne, Switzerland ; Universidade de Lisboa, Lisboa, Portugal) ; Pfister, Michael (EPFL, Lausanne, Switzerland ; School of Engineering and Architecture (HEIA-FR), HES-SO // University of Applied Sciences Western Switzerland) ; Matos, Jorge (Universidade de Lisboa, Lisboa, Portugal) ; Schleiss, Anton J. (EPFL, Lausanne, Switzerland)

Spillways are safety elements of dams that allow to release floods. They spill water to avoid overtopping with its potential structural damages at the dam and the downstream environment. Nevertheless it may be unsafe to assume that a flood only carries clear water. Large woody debris (LWD) are often transported by rivers into reservoirs during heavy rainfall events. There is still a lack of knowledge regarding the behaviour of LWD at spillway inlets. The accumulation and blockage of LWD at spillway inlets is a significant problem as it can change the load on the structure and also the functioning of the spillway by reducing the discharge capacity and increasing the reservoir water level. Once this point is reached, new conditions upstream are developed for the reservoir as head increase or enlargement of inundated areas. Literature provides mainly knowledge on the effect of LWD at bridges in rivers with relatively high flow velocities. However, information of the effects and consequences for reservoir approach flow conditions is generally unknown. Knowledge of the LWD blockage processes at a reservoir spillway may be vital regarding the safety evaluation of a dam. The present paper summarizes a series of laboratory experiments, where different LWD characteristics were related to blocking probabilities at an ogee crest spillway equipped with piers.

Type de conférence:
published full paper
Ingénierie et Architecture
iTEC - Institut des technologies de l'environnement construit
Adresse bibliogr.:
Chambéry, France, 29-30 November 2017
Chambéry, France
29-30 November 2017
8 p.
Publié dans:
Actes du Colloque CFBR-SHF : «Hydraulique des barrages et des digues", 29-30 novembre 2017, Chambéry, France
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