GIS-based hazard and risk maps of the Douro river basin (north-eastern Portugal)

Santos, José Gomes dos

doi:10.1080/19475705.2013.831952

Cited by 7 publications

(8 citation statements)

References 17 publications

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“…When the slope angle increases, the initial sliding mechanism may evolve into rapid debris flow that may be highly destructive (Zêzere et al 2007). Such slope movements occurred, for example, in the Douro Valley in January 2001 (Gomes 2013).…”

Section: Landslide Incidence In Mainland Portugal and São Miguel Islamentioning

confidence: 96%

Rainfall thresholds for landslide activity in Portugal: a state of the art

et al. 2014

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Rainfall is the most important physical process responsible for the landslide triggering in Portugal. Results obtained worldwide have shown that control of rainfall on landslides differs substantially depending upon landslide depth and kinematics and the affected material. Therefore, the critical rainfall conditions for failure are not the same for different types of landslides, and may be strongly influenced by regional geologic and geomorphologic conditions. Rapid debris flows are typically triggered by very intense showers concentrated in just a few hours, and shallow translational soil slips are usually triggered by intense precipitation falling within the 1-15 days long range. On the contrary, activity of deep-seated landslides of rotational, translational and complex types is related to periods of nearly constant rainfall, lasting from several weeks to several months. The different rainfall intensityduration conditions are associated with different hydrologic mechanisms for slope failure. The generation of surface run-off and high peak discharges in first-order mountain catchments is a critical triggering mechanism for debris flows. The intense rainfall allows the rapid growth of pore water pressure and the drop of capillarity forces that sustain the apparent cohesion of thin soils. As a consequence, shallow soil slips occur within the soil material or at the contact with the underlying less permeable bedrock. Long lasting rainfall episodes enable the steady rise of the groundwater table and the development of positive pore water pressures into the soil. Consequently, deep-seated failures occur in relation to the reduction of shear strength of affected materials. In this work, we present the state of the art concerning the proposition of empirical rainfall thresholds in Portugal for different types of landslides observed in different zones of the country: the Lisbon region, the Douro Valley and the NW Mountains, and the Povoação Municipality in São Miguel Island (Azores). The empirical thresholds applied in Portugal are based on the identification of past landslide events and include (i) the computation of antecedent rainfall threshold defined by linear regression, (ii) the normalization of rainfall by the mean annual precipitation, (iii) the definition of lower limit and upper limit rainfall thresholds and (iv) the definition of combined rainfall thresholds, which integrates the rainfall event and the antecedent rainfall for different time periods.

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Section: Landslide Incidence In Mainland Portugal and São Miguel Islamentioning

confidence: 96%

Rainfall thresholds for landslide activity in Portugal: a state of the art

et al. 2014

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“…LULC is typically one of the input parameters of models applied to several domains, e.g. environmental monitoring, multi-hazard risk & disaster modelling, urban & regional planning, natural resources management, or natural species distribution modelling [2,4,6,9,11,16,17,28,30,34]. As such, efforts and resources spent in creating LULC maps are well justified by official mapping agencies as well as scientific researchers who constantly seek higher detail and quality at lower cost [8-10, 14, 29-31, 35].…”

Section: Introductionmentioning

confidence: 99%

Automatic conversion of OSM data into LULC maps: comparing FOSS4G based approaches towards an enhanced performance

Patriarca

Fonte

Estima

et al. 2019

Open geospatial data, softw. stand.

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OSM2LULC is a software package developed to automatically convert OpenStreetMap (OSM) data into Land Use Land Cover (LULC) maps using Free and Open Source Software for Geospatial (FOSS4G) tools. It needs to be highly efficient given the increasing detail of OSM data and the need to apply it to large extent regions. In this article, a comparison between the implementation of OSM2LULC in different available GIS platforms is made using both vector and raster data structures, which resulted in different versions. A description of the differences of each version is made and, to assess their performance, they were applied to four different study areas with different characteristics, in terms of available OSM data and area size. The performance of each version was evaluated taking into account: the overall processing time required to obtain LULC maps; and differences in the results obtained when different data structures (vector and raster) were used. Results showed that the adoption of a strategy that favors interoperability between FOSS4G and the combined use of both vector and raster data promotes a performance increase. After analysing the topological relationships of OSM data, the conversion to raster data format and the execution of procedural parts with such data indicated significant performance gains, without any positional distortions that significantly compromise the applicability of the final result in further case scenarios.

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“…Using the set of regional technical and thematic maps listed in Table 1, a series of spatial analyses was performed to compare each slope instability phenomenon with the geological, geomorphological and land-use settings of the Entella River catchment. We selected the following geological, morphological, environmental and anthropogenic factors which influence the stability of the slopes and the occurrence of landslides, and we evaluated the incidence of slope movements according to these categories: lithology, slope aspect and steepness [39,73], drainage and land-use [39,[76][77][78], man-made structure, e.g., distance from roads and buildings [39,76,77,79], and existing gravitational processes. At this stage, a new source of uncertainty has been introduced due to the modelling of the predisposing parameters used in the thematic maps that we acquired from the regional cartographical archives.…”

Section: Methodsmentioning

confidence: 99%

Heavy Rainfall Triggering Shallow Landslides: A Susceptibility Assessment by a GIS-Approach in a Ligurian Apennine Catchment (Italy)

Roccati

Faccini

Luino

et al. 2019

Water

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In recent decades, the Entella River basin (eastern Liguria) has been affected by several rainfall events that induced widespread shallow landslides and earth flows on the slopes; roads, buildings, structures and infrastructure suffered extensive damage due to the instability processes. In this paper, a GIS-based approach for analyzing and assessing a simplified landslide susceptibility in the Entella River catchment is presented. Starting from landslide information mainly provided from newspaper articles and unpublished reports from municipal archives, we performed a series of comparative analyses using a set of thematic maps to assess the influence of predisposing natural and anthropic factors. By evaluating the statistical distribution of landslides in different categories, we assigned weighted values to each parameter, according to their influence on the instability processes. A simplified, reproducible, but effective approach to assess landslide susceptibility in the study area was performed by combining all predisposing factors. The resulting scores in proneness to slope instability classes may be used to generate a simplified landslides susceptibility map of the catchment area which would be easy to regularly update every time a rainfall event that is able to trigger shallow landslides occurs; this would provide a useful tool for local authorities and decision makers for identifying areas which could potentially be affected by instability processes, and would help in determining the most suitable measures in land-planning and landslide risk management.

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GIS-based hazard and risk maps of the Douro river basin (north-eastern Portugal)

Cited by 7 publications

References 17 publications

Rainfall thresholds for landslide activity in Portugal: a state of the art

Rainfall thresholds for landslide activity in Portugal: a state of the art

Automatic conversion of OSM data into LULC maps: comparing FOSS4G based approaches towards an enhanced performance

Heavy Rainfall Triggering Shallow Landslides: A Susceptibility Assessment by a GIS-Approach in a Ligurian Apennine Catchment (Italy)

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