Slope, Scarp and Sea Cliff Instability Susceptibility Mapping for Planning Regulations in Almada County, Portugal

World Multidisciplinary Earth Sciences Symposium 2017

Marques, Fernando^1 ; Queiroz, Sónia^2 ; Gouveia, Luis^2 ; Vasconcelos, Manuel^3

University of Lisbon, Faculty of Sciences, Department of Geology, Dom Luiz Institute, Faculdade de Ciencias, Campo Grande, edificio C6, 3 piso, Lisboa

1749-016, Portugal^1

Dom Luiz Institute, Faculdade de Ciencias, Universidade de Lisboa, Campo Grande Edificio C1, Piso 1, Lisboa

1749-016, Portugal^2

ESRI Portugal, Rua Julieta Ferrao, 10 - 10 A, Lisboa

1600-131, Portugal^3

关键词: Generalization process;    Landslide inventories;    Municipal authorities;    National ecological reserves;    Pixel based approach;    Planning regulations;    Susceptibility mapping;    Sustainable land use;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/95/2/022022/pdf
DOI  :  10.1088/1755-1315/95/2/022022

来源: IOP

【 摘 要 】

In Portugal, the modifications introduced in 2008 and 2012 in the National Ecological Reserve law (REN) included the mandatory study of slope instability, including slopes, natural scarps, and sea cliffs, at municipal or regional scale, with the purpose of avoiding the use of hazardous zones with buildings and other structures. The law also indicates specific methods to perform these studies, with different approaches for slope instability, natural scarps and sea cliffs. The methods used to produce the maps required by REN law, with modifications and improvements to the law specified methods, were applied to the 71 km2territory of Almada County, and included: 1) Slope instability mapping using the statistically based Information Value method validated with the landslide inventory using ROC curves, which provided an AAC=0.964, with the higher susceptibility zones which cover at least 80% of the landslides of the inventory to be included in REN map. The map was object of a generalization process to overcome the inconveniences of the use of a pixel based approach. 2) Natural scarp mapping including setback areas near the top, defined according to the law and setback areas near the toe defined by the application of the shadow angle calibrated with the major rockfalls which occurred in the study area; 3) Sea cliffs mapping including two levels of setback zones near the top, and one setback zone at the cliffs toe, which were based on systematic inventories of cliff failures occurred between 1947 and 2010 in a large scale regional littoral monitoring project. In the paper are described the methods used and the results obtained in this study, which correspond to the final maps of areas to include in REN. The results obtained in this study may be considered as an example of good practice of the municipal authorities in terms of solid, technical and scientifically supported regulation definitions, hazard prevention and safe and sustainable land use management.