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Al fine di valutare le condizioni limite per la stabilità di un pendio in frana, sono state svolte delle analisi di stabilità all’equilibrio limite 2D e 3D in un’area ubicata nel bacino del fiume Imera Settentrionale (Sicilia). Tali analisi hanno permesso di ricostruire un modello geologico e geotecnico ottimale, di individuare il livello piezometrico che ha determinato le condizioni di instabilità e di definire i parametri operativi di resistenza a taglio dei terreni. Le recenti riattivazioni dei meccanismi di frana hanno fornito elementi che hanno permesso di validare in particolare i risultati delle analisi numeriche 3D. I risultati ottenuti hanno anche evidenziato che il metodo di analisi tridimensionale costituisce un valido strumento di analisi, capace di prevedere l’estensione areale dei dissesti e di fornire una migliore stima della resistenza a taglio operativa dei terreni, soprattutto nei casi in cui la morfologia del pendio è complessa e la direzione degli spostamenti non è omogenea.

Calanchi (singular calanco) represent a typical example of badlands in the Italian peninsula, which rapidly evolve on clayey terrains such as the widespread Pliocene-Pleistocene marine clays. The present study aimed at investigating the role of the slope morphometry on the typology and distribution of morphogenetic processes in a calanchi area located in southern Italy. The research included detailed geomorphological surveying, morphometric and statistical analysis. The study area was first subdivided into individual hydrographic units (HUs), for which field survey allowed to identify the dominant denudation processes, their intensity and the distribution of the associated landforms (pipes, rills, gullies, landslides). The morphometry of each HU was characterized by calculating the Morphometric Slope Index (MSI) on a reconstructed digital elevation model (DEM). By statistically comparing the morphogenetic and morphometric data, the influence of the slope morphometry on the type, distribution and evolution of the calanchi erosion process has been highlighted. In particular, through a Cluster Analysis the groups of HUs having similar dominant processes were identified and, by applying the Analysis of the Variance, the effect of the MSI on the identified clusters was analysed. Two clusters were identified which revealed the relative importance of morphogenetic processes and the strict connection between surface and subsurface landforms. These two clusters were discriminated by the MSI value (high MSI favoured mass movements, whilst low MSI favoured gully erosion and piping), highlighting the importance of slope morphometry in driving the morphogenetic hillslope processes.

Geomorphology for Society, Conference proceedings

The determination of soil properties is considerable challenge when it is aimed to evaluate the spatial distribution of one or more parameters across significant surfaces. In fact, terrain sampling and field data are punctual measurement; therefore, quantitative models are needed to predict the spatial distribution of soil attributes. The spatialization of field and laboratory data is a very important information in landslide studies. Raster layers displaying soil properties can be used both for statistical models and for the parameterization of physically based models. The purpose of this work is to produce a detailed hydrological and mechanical characterization of the soil affected by shallow landsliding processes. The study area is located in Messina (Southern Italy) where a debris flow event occurred on the 1st October 2009. In particular, two small and independent (2 km2) hydrological units were chosen: Racinazzi and Saponarà catchments. The sample sites were selected using a provisional predictive pedologic model based on the topographic attributes Topographic Wetness Index and Steepness of slope. The field analyses were aimed to determine soil thickness, hydraulic conductivity and other soil mechanical properties. The fieldwork was carried out using: (1) Dynamic Cone Penetrometer (2) Amoozemeter (3) Auger sampler. The laboratory analysis of the collected samples have performed in order to characterize granulometry and the Atterberg limits. Stochastic approaches have been then adopted to regionalize the punctual information for each of the collected properties resulting in robust spatial distributions used to characterize landslide prone conditions. The results show the slope instability mainly affect the terraced areas characterized by the presence of a thin layer of soil which, according to the laboratory analysis, testifies an incomplete pedogenesis.

The “Ecological Cross-­‐border Networks Malta-­‐Sicily” (RE.MA.SI.) is an international research project founded by the Italia-­‐Malta 2007-­‐2013 Programme. A part of the project aims to carry out a multidisciplinary study for the identification and enhancement of geosites in the Maltese Islands and Sicily. Some areas have been picked out; these areas are spectacular and interesting for the tourists and can make a significant contribution to the understanding the geological and geomorphological history. Field surveys took place for the identification and classification of the most significant geomorphosites and the verification of the collected bibliographical data; in particular, the identification and selection process concentrates on the following range of values: scientific, additional and use. By application of these already tested qualitative guidelines, the obtained territorial data have been put on in a standard forms in order to create a common geomorphosite inventory and a GIS-­‐database. An example of this approach for the Torre Salsa natural reserve located on the southern coast.

Malta and Sicily show common geological and geomorphological features, having been also physically linked not later than the Last Glacial Maximum. At present both islands have a high tourist vocation, but their environmental potential is not fully exploited for attracting tourists and visitors. In the framework of an international research project, “Ecological Cross-border Networks Malta-Sicily” (RE.MA.SI.), a multidisciplinary study for the identification, selection and enhancement of geosites in the Maltese and Sicilian islands was carried out. A number of sites both in Malta and Sicily have been identified and qualitatively and quantitatively assessed applying a methodology already tested in previous studies. The aim was to see whether any of these sites could be considered as geosites of geomorphological interest (geomorphosites) according to scientific, additional and use values. In order to create a common geomorphosite inventory and a GIS-database, the standard forms of the Italian Institute for Environmental Protection and Research (ISPRA) were used. The recognised and assessed geomorphosites mainly include coastal and kart features, but also landslides, badlands and mud volcanoes are encountered due to their scientific interest and scenic value. The research enabled us to highlight that geomorphosites can become a relevant resource for social and economic development in Malta and Sicily, and can provide the ground for bridging these islands through a new integrated approach with foresees common methods and actions for geoheritage exploitation and enforcement of conservation strategies.

The SUFRA project is based on a three level susceptibility mapping. According to the availability of more detailed data, the three scale for susceptibility mapping are increased respect to the ones suggested by the TIER group to 1:100,000, 1:50,000 and 1:25,000/1:10,000. The mapping levels exploit climatic, soil use (CORINE2009) and seismic informative layers, differentiating in the details of the core data (geology and topography), in the quality and resolution of the landslide inventory and in the modelling approach (Tab. 1). SUFRA_100 is based on a heuristic approach which is applied by processing a geologic layer (produced by ARTA integrating pre-CARG 1:100,000 geologic maps); the DEM exploited are IGMI 250m and the mapping units are 1km side square cells. Models are validated with respect to the PAI LIPs (Landslide Identification Points) which are reclassified adopting a simplified scheme. Output cuts of SUFRA100 will be referred to administrative boundaries (provinces). SUFRA50 is based on statistical analysis of new CARG geologic maps and 20m (ITA2000) - 2m (ATA2007) DEM. The mapping units are 500m and 50m cells, hydrographic and hydro-morphometric units. The landslide inventory is the IFFI2012_LIPs (first level) which is the result of the conversion in IFFI format of the PAI archive, which will be supported by remote landslide mapping (exploiting the ATA2007 aerial photos), according to the IFFI first level approach. Validation of the models will be performed exploiting both random spatial partition and temporal partition methods. Output cuts of SUFRA50 will be based on physiographic (basin) and administrative (municipalities) boundaries. SUFRA10/25 is based on statistical analysis of new CARG geologic maps (remotely and field adapted) and 2m (ATA2007) DEM. The mapping units are the slope units (SLUs) which are derived by further partitioning the hydro-morphometric units so to obtain closed morphodynamic units. The landslide inventories is the IFFI2012 which is the results of a field supported (on focus) landslide remote systematic mapping, according to the IFFI full level approach. Examples of SUFRA_100, SUFRA_50 and SUFRA_10 are presented for some representative key sector of Sicily. First results attest for the feasibility and goodness of the proposed protocol. The SUFRA program aims at enabling the regional governmental administration to cope with landslide prevision, which is the required operational concept in land management and planning. PAI has been a great advance with respect to the “pre-SARNO” conditions, but it is very exposed to fail: it is a blind approach for new activations; it is critically dependent on the quality of the landslide inventories; it cannot project the susceptibility outside the landslide areas

In the framework of a regional landslide susceptibility study in southern Sicily, a test has been carried out in the Tumarrano river basin (about 80 km2) aimed at characterizing its landslide susceptibility conditions by exporting a ‘‘source model’’, defined and trained inside a limited (about 20 km2) representative sector (the ‘‘source area’’). Also, the possibility of exploiting Google Earth TM software and photo-images databank to produce the landslide archives has been checked. The susceptibility model was defined, according to a multivariate geostatistic approach based on the conditional analysis, using unique condition units (UCUs), which were obtained by combining four selected controlling factors: outcropping lithology, steepness, plan curvature and topographic wetness index. The prediction skill of the exported model, trained with 206 landslides, is compared with the one estimated for the whole studied area, by using a complete landslide archive (703 landslides), to see to what extent the largest time/money costs needed are accounted for. The investigated area stretches in the fore-deep sector of southern Sicily, where clayey rocks, mainly referring to the Numidian Flysch and the Terravecchia Formations, largely crop out. The results of the study confirm both the exploitability of Google Earth TM to produce landslide archive and possibility to adopt in assessing the landslide susceptibility for large basin, a strategy based on the exportation of models trained in limited representative sectors.

L’attuale versione del PAI (Piano Stralcio per l'Assetto Idrogeologico) disponibile per il territorio siciliano è fortemente dipendente dallo scenario di dissesti passati censiti e catalogati, sulla base dei quali, utilizzando un sistema di matrici di valutazione, è possibile ricavare le condizioni di rischio geomorfologico associato. Questo stadio costituisce un primo grande avanzamento delle conoscenze a partire dal quale è ora necessario procedere alla valutazione della suscettibilità da frana e all’adozione dunque di uno strumento di analisi territoriale con carattere previsionale. La realizzazione di una cartografia della suscettibilità da frana a scala regionale pone d’altra parte una serie di problemi di approccio e di tecnica realizzativa, che derivano dalla necessità di trovare un compromesso tra estensione territoriale e risoluzione dei modelli previsionali e, dunque, di risoluzione dei dati necessari in ingresso. Il progetto SUFRA muove dalla stessa analisi metodologica del progetto TIER ma, alla luce della disponibilità per il territorio siciliano di tematismi geologici con maggiore dettaglio e inventari delle forme franose densamente popolati, diverge da questo sia nei dati in ingresso sia nei metodi di costruzione dei modelli, che vengono implementati per la valutazione della suscettibilità nei tre livelli in Sicilia. Tutti i livelli di mappatura sfruttano strati informativi con informazioni riguardo alla geologia, al clima, all’uso del suolo e ai dati sismici. Il progetto SUFRA mira dunque a realizzare una cartografia a varia scala della suscettibilità, articolata secondo i tre livelli: SUFRA100 (scala 1:100,000), SUFRA50 (scala 1:50,000) e SUFRA25/10 (scala 1:25,000 o 1:10,000). SUFRA100 è basato su un approccio euristico utilizzando un DEM con cella di 250 metri derivato dall’IGMI. Le unità di mappatura sono celle quadrate di 1 km di estensione. I modelli sono validati rispetto ai LIP (punti identificazione della frana) che vengono riclassificati con adozione di una semplificazione in due sole principali tipologie (frane di scarpata e frane di versante) dell’archivio PAI, disponibile per tutto il territorio regionale. La rappresentazione di uscita, a questo livello saranno limiti amministrativi come quelli comunali o provinciali. SUFRA50 si basa sull'analisi statistica sfruttando la disponibilità delle nuove carte geologiche (CARG) e un DEM ottenuto ricampionando a celle di 20 metri di lato il DEM ATA2007/08. L’inventario delle frane, utilizzato per questo livello è l’IFFI2012_LIP (solamente il primo livello) che è il risultato della conversione in formato IFFI dell'archivio PAI, che sarà supportato e implementato da un controllo remoto delle aree individuate (sfruttando le foto aeree ATA2007). La rappresentazione di uscita del SUFRA50 sarà basata su confini fisiografici (bacini idrografici) e/o amministrative (comuni). SUFRA10/25 si basa sull'analisi statistica delle carte CARG (verificate con un lavoro di campagna) e sfruttando l’alta risoluzione del DEM ATA2007. Le unità di mappatura di base corrispondono alle unità di versante (SLU), derivate da una nuova ripartizione delle unità idromorfometriche in modo da ottenere unità con coerenza morfodinamica. Gli inventari di frana sono il risultato di una successiva implementazione dell’archivio IFFI2012, controllato e verificato da remoto e con indagini di campo. Esempi di SUFRA_100, SUFRA_50 e SUFRA_10 sono stati realizzati per qualche settore rappresentativo di diversi contesti geologici e geomorfologici Siciliani. I primi risultati attestano per la fattibilità e la bontà del protocollo proposto.

In the present research, two neighbouring calanchi fronts have been monitored by means of repeated readings on erosion pins, that were carried out between November 2006 and October 2008. During the monitoring period, a gauge station has been recording rainfalls, allowing us to compute the Rainfall-Runoff Erosivity Factor of the USLE model. The research highlighted: i) a general correspondence between rainfalls temporal trends and surface variation rhythms; ii) alternating erosion and deposition phases result in a retreat of the “calanchi” fronts.

A GIS-analysis was carried out in a test basin of southern Sicily, the Magazzolo River basin, in order to assess susceptibility conditions to gully erosion phenomena. The linear density of ephemeral and permanent gullies computed within each class of nine environmental variables was used to generate a gully erosion susceptibility map for the area. A validation procedure carried out in order to test the reliability of the adopted method highlighted a clear correlation between the occurrence of gullies and the computed susceptibility levels