Abstract:
The engineering geology of the West Algarve coastline between Cape St Vincent in the west and Fare in the east varies considerably, from the high limestone cliffs between Salema and Burgau to the lower but more problematic karstic cliffs around Lagos and east of Portimao. Geotechnical problems vary from toppling failure and rockfalls in the higher, more heavily jointed limestone and sandstone cliffs between Salema and Burgau, to sinkhole collapse, subsidence and gullying within the Miocene calcarenites and Pleistocene sands east of Portimao. This latter area is the subject of this paper. Field mapping was completed on scales of 1:2000 and 1:5000 to encompass geomorphology, geology and vegetation cover. Both sinkhole and sea cliff formation controlling factors are discussed and subsequently nine factors affecting potential hazard location are identified. The relative importance of these ten factors is determined and then each cell, 100 m(2) in size, is assessed for its individual score relative to the presence of, or degree of influence of each of the hazard forming processes. The resulting composite hazard map is aimed at planners and developers as a multipurpose map for general use. (C) 1999 Elsevier Science B.V. All rights reserved