Urban geomorphology of Genoa old city (Italy)

Field survey and geomorphological mapping in urban areas are difficult tasks, particularly those related to the recognition of natural landforms within cities. In this case, it is necessary to apply an integrated scientific approach by combining geomorphology with historical-geography. This paper presents the result of a multi-year survey carried out in the natural morphological amphitheatre where the historic centre of Genoa developed. Our research methods included field surveys in urban areas, interpretation of natural and anthropic landforms from maps and photographs, and analyses of the available borehole logs. As a result, we updated knowledge on urban geomorphology of Genoa old city. An original geomorphological legend has been adopted, including new entries for anthropogenic landforms, targeted at a better visual representation on the changes in the geomorphological landscape during more than one thousand years of urban development of the city. The geomorphological map of Genoa old city is presented as a useful tool for urban planning, as well as for an integrated cultural and landscape enhancement of the territory

Investigation on Farmland Abandonment of Terraced Slopes Using Multitemporal Data Sources Comparison and Its Implication on Hydro-Geomorphological Processes

This paper presents a quantitative multi\u2010temporal analysis performed in a GIS environment and based on different spatial information sources. The research is aimed at investigating the land use transformations that occurred in a small coastal terraced basin of Eastern Liguria from the early 1950s to 2011. The degree of abandonment of cultivated terraced slopes together with its influence on the distribution, abundance, and magnitude of rainfall\u2010induced shallow landslides were accurately analysed. The analysis showed that a large portion of terraced area (77.4%) has been abandoned over approximately sixty years. This land use transformation has played a crucial role in influencing the hydro\u2010geomorphological processes triggered by a very intense rainstorm that occurred in 2011. The outcomes of the analysis revealed that terraces abandoned for a short time showed the highest landslide susceptibility and that slope failures affecting cultivated zones were characterized by a lower magnitude than those which occurred on abandoned terraced slopes. Furthermore, this study highlights the usefulness of cadastral data in understanding the impact of rainfall\u2010induced landslides due to both a high spatial and thematic accuracy. The obtained results represent a solid basis for the investigation of erosion and the shallow landslide susceptibility of terraced slopes by means of a simulation of land use change scenarios

shallow landslides susceptibility assessment in different environments

The spatial distribution of shallow landslides is strongly influenced by different climatic conditions and environmental settings. This makes difficult the implementation of an exhaustive monitoring technique for correctly assessing the landslide susceptibility in different environmental contexts. In this work, a unique methodological strategy, based on the statistical implementation of the generalized additive model (GAM), was performed. This method was used to investigate the shallow landslide predisposition of four sites with different geological, geomorphological and land-use characteristics: the Rio Frate and the Versa catchments (Southern Lombardy) and the Vernazza and the Pogliaschina catchments (Eastern Liguria). A good predictive overall accuracy was evaluated computing by the area under the ROC curve (AUROC), with values ranging from 0.76 to 0.82 and estimating the mean accuracy of the model (0.70–0.75). The method showed a high flexibility, which led to a good identification of the most significant predisposing factors for shallow landslide occurrence in the different investigated areas. In particular, detailed susceptibility maps were obtained, allowing to identify the shallow landslide prone areas. This methodology combined with the use of the rainfall thresholds for triggering shallow landslides may provide an innovative tool useful for the improvement of spatial planning and early warning systems

On the estimation of landslide intensity, hazard and density via data-driven models

Maps that attempt to predict landslide occurrences have essentially stayed the same since 1972. In fact, most of the geo-scientific efforts have been dedicated to improve the landslide prediction ability with models that have largely increased their complexity but still have addressed the same binary classification task. In other words, even though the tools have certainly changed and improved in 50 years, the geomorphological community addressed and still mostly addresses landslide prediction via data-driven solutions by estimating whether a given slope is potentially stable or unstable. This concept corresponds to the landslide susceptibility, a paradigm that neglects how many landslides may trigger within a given slope, how large these landslides may be and what proportion of the given slope they may disrupt. The landslide intensity concept summarized how threatening a landslide or a population of landslide in a study area may be. Recently, landslide intensity has been spatially modeled as a function of how many landslides may occur per mapping unit, something, which has later been shown to closely correlate to the planimetric extent of landslides per mapping unit. In this work, we take this observation a step further, as we use the relation between landslide count and planimetric extent to generate maps that predict the aggregated size of landslides per slope, and the proportion of the slope they may affect. Our findings suggest that it may be time for the geoscientific community as a whole, to expand the research efforts beyond the use of susceptibility assessment, in favor of more informative analytical schemes. In fact, our results show that landslide susceptibility can be also reliably estimated (AUC of 0.92 and 0.91 for the goodness-of-fit and prediction skill, respectively) as part of a Log-Gaussian Cox Process model, from which the intensity expressed as count per unit (Pearson correlation coefficient of 0.91 and 0.90 for the goodness-of-fit and prediction skill, respectively) can also be derived and then converted into how large a landslide or several coalescing ones may become, once they trigger and propagate downhill. This chain of landslide intensity, hazard and density may lead to substantially improve decision-making processes related to landslide risk

Il paesaggio costiero dei versanti terrazzati delle cinque terre: un patrimonio culturale ed ambientale a elevato rischio geomorfologico

Gli interventi di mitigazione del rischio geomorfologico realizzati nelle Cinque Terre attraverso procedure di emergenza in fase post alluvione, sono sostanzialmen- te riconducibili ad una serie di opere strutturali localizzate per mettere in sicurezza, con effetti a breve termine, gli edifici e le strade maggiormente esposti a fenomeni di pericolosit\ue0 lungo i versanti ed i tratti di corsi d\u2019acqua pi\uf9 problematici (Brandolini e Cevasco, 2014). A tal fine sui versanti sono state costruite barriere flessibili, consolidamenti con micropali e ricostruiti alcuni settori di muri in pietra a secco. Lungo i corsi d\u2019acqua sono stati realizzati interventi di allargamento delle sezioni di deflusso, l\u2019innalzamento degli argini ed in particolare sono state costruite una decina di barriere frangi-colata nei tratti di reticolo pi\uf9 pericolosi. Per garantire una mitigazione del rischio geomorfologico, con effetti a lungo ter- mine, sono per\uf2 urgentemente necessarie strategie di prevenzione a scala di bacino, prevedendo nel caso specifico delle Cinque Terre una vasta azione di recupero delle aree terrazzate e dei relativi sistemi di drenaggio, nonch\ue9 una risistemazione idraulico- forestale delle aree a bosco presenti nelle parti pi\uf9 alte dei versanti. In un contesto di straordinario valore come quello delle Cinque Terre, le strategie di pianificazione e gestione del territorio dovranno pertanto prendere in considerazione al contempo la necessit\ue0 di contrastare con urgenza i pericoli geomorfologici e di preser- vare il patrimonio culturale ed ambientale del paesaggio terrazzato. Questo si potr\ue0 realizzare solo attraverso un fondamentale ed indispensabile recu- pero delle attivit\ue0 agricole da associare ad uno sviluppo sostenibile del turismo, dal quale poter attingere almeno in parte le risorse economiche necessarie per finanziare la salvaguardia e il recupero del territorio