Landslide cartographic susceptibility and hazard landscape units in a regional scale: the case stude of Figueira da Foz – Nazaré region

Abstract

The coastal plain located betwen Figueira da Foz and Nazaré (western Portugal) has a general low slope towards west, presents elevations below 200 m a.s.l. and constitutes an important geomophological unit in this area. Towards north, east and south the platform is limited by the limestone relieves of the Serra da Boa Viagem – Verride arc, Sicó Massif and Estremenho Massif, respectivelly. These relieves are characterized by high slope values and also higher altitudes (> 200 m). The area comprises the terminal portion of the hydrographic basins of the Mondego and Lis rivers. Regionally six territorial units were distinguished which, given the characteristics of natural systems and the development of human activities, determine different areas of risk: the limestone hills, the sandy hills, floodplains, coastal plain the coastline and the probable neotectonic structures. The limestone hills are particularly sensitive to mass movements (mainly landslides), the sandy hills are vulnerable not only to movements and fluvial erosion, but also to forest fires. Alluvial plains are vulnerable to floods and overflooding, coastal plain and its eolian dune field could be very vulnerable to forest fires, the coastline presents high vulnerability to erosion of different types according to morphology of the coast and, finally, the active tectonic structures, particularly those that are related with diapirs, are a source of seismic risk. It is our goal with this study, to create a GIS project covering diverse thematic mapping (lithologies, tectonics, slopes, hydrology, land use), to do data spatial analysis, particularly in anticipation of the hypothetical scenarios of rising sea level, floods, forest fires and slope movements.