Susceptibility assessment of rainfall-triggered flows and slides in the Central-Eastern Pyrenees

Abstract

Rainfall-induced flows and slides are hazardous processes in mountainous regions and suscep-tibility assessments with resulting maps are helpful tools for land-use planners. In the present study, all the available information on recent events has been gathered and incorporated in an inventory. The governing fac-tors of the 2262 entries were analyzed and preliminary susceptibility matrices were established. Two different terrain units were applied and compared: grid cells and first-order catchments. The results showed that slope angle between 30 and 35º and land cover classes like debris screes or grassland are the most significant fac-tors. In addition, the Melton Ratio higher than ~0.7 in the first-order catchments seems to be another critical parameter. Finally, two types of susceptibility maps were created, although the ones working with first-order catchments look more appropriate for the application at regional scale and the use for land-use planning.