Effects of forest fire on the hydrological response of a Mediterranean drainage basin (Arbúcies River, Catalan Coastal Ranges, NE Spain)

Abstract

We analyse the hydrological response of the Arbúcies River basin after a wildland fire occurred in August 1994, which burnt 15% of its drainage area. The Arbúcies River is located in the Catalan Coastal Ranges, draining an area of 106 km2. Deep sandy soils are predominant in the catchment. The study is based on rainfall and runoff records (1991-1997), from which twenty-six flood events were selected. River response, especially runoff volume and peak discharge, showed a remarkable increment for events occurred six months after the fire, in comparison with those of similar magnitude prior the fire. The higher the magnitude of the episodes the higher the degree of hydrological alteration. Maximum increment of peak discharge is 173%, which is susbtantially more important that that produced on the effective rainfall (+40%). Flood events tend to recover pre-fire hydrological response eighteen months after the fire.