Premium
The 1996 Biescas campsite disaster in the Central Spanish Pyrenees, and its temporal and spatial context
Author(s) -
White Sue,
GarcíaRuiz José M.,
Martí Carlos,
Valero Blas,
Errea M. Paz,
GómezVillar Amelia
Publication year - 1997
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/(sici)1099-1085(199711)11:14<1797::aid-hyp605>3.0.co;2-7
Subject(s) - tributary , hydrology (agriculture) , context (archaeology) , storm , flood myth , drainage basin , return period , geology , sediment , channel (broadcasting) , environmental science , geography , geomorphology , oceanography , archaeology , cartography , paleontology , geotechnical engineering , engineering , electrical engineering
On the evening of the 7 August 1996 an intense storm occurred over the Arás catchment near Biescas in the central Pyrenees. Eighty‐seven people were killed as a result of the subsequent flood, which hit a campsite located on the alluvial fan at the outlet of the 18·8 km 2 catchment. This paper presents the main results of a hydromorphological study of the event. The Betés subcatchment received the most intense rainfall, estimated at somewhat in excess of 250 mm, which resulted in a peak flow from this tributary of 300 m 3 s −1 . Just downstream from the Betés river junction, flow in the main channel reached 400 m 3 s −1 , increasing to around 500 m 3 s −1 further downstream. Rainfall in the larger Aso tributary was less intense, and in the head reaches flow remained within‐bank, representing a one in two‐year return period event. Flow from this tributary did not exceed 100 m 3 s −1 , indicating that the Betés subcatchment supplied some 75% of the flow from just 28·7% of the catchment area. The extreme flows caused the collapse of a series of sediment trap dams in the Arás channel downstream of the Betés junction. This resulted in the addition of 68 000 m 3 of sediment to an already disastrous event. Data from other rain gauges in the area showed both the extremely local nature of the event, and the problems of return period analysis for such storms, whose peaks are rarely observed at gauges. Together with the high geomorphological risks of the zone, this leads to the conclusion that a new method of spatial and temporal risk analysis is required for infrastructure planning. © 1997 John Wiley & Sons, Ltd.