Hydrodynamic and sedimentary interpretation of the San Juan Dam break (Altorricón, Huesca)
Authors
R.J. Batalla
Universitat de Lleida
J.C. Balasch
Universitat de Lleida
Keywords:
balsa de riego, rotura, materiales cuaternarios, erosión, deposición, crecida, flujo hiperconcentrado, balance de sedimentos
Abstract
This study presents a hydrodynamic and sedimentary reconstruction and interpretation of the San Juan dambreak occurred in January 2001 in Altorricón (Huesca). Geomorphic processes as well as erosional and depositional forms created by released water and sediment are also described. Approximately 300,000 m3 of water were released during the outflow following an estimated peak of 172 m 3 s-1. As a consequence, 3,350 metric tones of sediment were entrained, 80% of them subsequently deposited as an alluvial fan at the dam-break footstep. Metric blocs were transported by hyperconcentrated flows around 1.35 t m-3 in density. Dam break and collapse were mainly triggered by hypodermic fluxes and piping. Non-adequate sealing of the dam bottom and the inappropiate location on top of highlypermeable Quaternary sediments can be pointed out as main causes of the disaster.
