HYDROMETEOROLOGICAL AND GEOMORPHOLOGICAL ASPECTS

OF THE 1994 EXTREME FLOODS IN NORTHEASTERN SPAIN

Jordi Corominas

E.T.S. Ingenieros de Caminos

Universitat Politecnica de Catalunya

Gran Capitan s/n Edificio D-2

08034 Barcelona, Spain

Enrique Velasco and Josep Ma. Montes

Junta d’Aigues

Generalitat de Catalunya

Beethoven 15

08021 Barcelona, Spain

Three consecutive rainy events seriously affected coastal ranges of Catalonia, Eastern Spain. Rainfall records exceeded 200 mm in 48 hrs in most of the region, while values over 300 mm were reached in some spots. In basins of less than 100 km² measured unit river discharges ranged from 3 to 7 m³/s.km². These values are among the highest recorded in the region. Flash flood are common in most of these rivers. In upper river reaches, the steep bed slope led to bed scouring and the mobilisation of large boulders (over 1 m³) while on lower reaches, aggradation made the former flood plain to rise and to built alluvial fan. This scour-deposition dynamics caused severe damage on river training works and nearby infrastructure.