Ground movement risk in 'Las Batuecas-Sierra de Francia' and 'Quilamas' nature parks (central system, Salamanca, Spain)

Ground movements constitute active processes that modify the disposition and morphology of the earth's surface. This work establishes a cartography procedure to obtain a ground movement risk map at a 1:50,000 scale. Such a map would be useful for establishing mitigation measures for land use planning and management in natural spaces, using Geographic Information Systems (GIS). A number of steps are taken to produce the map in GIS. First, a susceptibility map is created by considering passive or conditioning factors, which depend on the nature, structure and morphology of the ground. Second, a hazard map is created by considering active or trigger factors, which cause instabilities within hillsides and determine the magnitude and speed of their movements. Finally, the ground movements risk map is obtained by combining the susceptibility and hazard maps with risk and vulnerability map (degree of potential damage) and risk exposure map (estimate of damage, human casualty and economic loss). The resulting ground movements risk map shows very high risk at the foot of escarpments and abrupt reliefs where urban areas, fractures and/or roads are present. High risk prevails in the geomorphologic domains of fluvial incisions, where the slopes are high, as well as in areas with escarped hillsides. Medium-risk areas are distributed around the marked reliefs, forming zones of filling and slightly flat surfaces. Low-risk areas appear in topographically flat areas, since they are domains of terraces, pediments or degraded surfaces. Very scattered and less-extended areas present very low risk.