Paolo Magliulo

Comparison of GIS-based methodologies for the landslide susceptibility assessment

In this paper, two simple GIS-based methodologies have been used to assess the landslide susceptibility in a basin located in Southern Italy. The methodologies at issue, based on the spatial distribution of landslides and/or of causal factors, are bivariate statistics-based and expert-based, respectively. The spatial distribution of both the landslides and the causal factors has been investigated by integrating pre-existing and original data, which have been processed using ArcView GIS 3.2 software. The obtained results, consisting of landslide susceptibility maps have been compared and discussed. The bivariate statistics-based method has provided the most satisfying results. On the contrary, the expert-based method has provided a classification of the study area in terms of landslide susceptibility which does not completely fit with the surveyed spatial distribution of the landslides.

Assessing the susceptibility to water-induced soil erosion using a geomorphological, bivariate statistics-based approach

The aim of this study was the assessment, at basin scale, of the susceptibility to water-induced soil erosion processes (i.e. gully erosion and sheet/rill erosion) using geomorphological analysis, Geographical Information Systems (GIS) and bivariate statistics. The study was carried out in a watershed located in Southern Italy. A detailed analysis of the pre-existing literature led to select lithology, land-use, slope angle and slope aspect as soil-erosion determining factors (DFs), as they are “non-redundant” and affect both the soil-forming processes that control soil erodibility and the erosive power of running waters. Water-produced erosional landforms, such as gullies and areas severely affected by sheet/rill erosion, were surveyed and mapped using classical techniques of geomorphological analysis. The GIS processing of the geomorphological data allowed calculating the areal density of these landforms in each DF class. Weighting values (Wi), corresponding to the susceptibility level of each DF class, were calculated using bivariate statistics. Finally, GIS overlay procedures of the thematic maps, previously reclassified on the basis of the calculated Wi, allowed to produce two Susceptibility Maps (i.e. Gully Erosion and Sheet and/or Rill Erosion Susceptibility Map). The soil-geomorphological coherence of the produced results has been checked and widely discussed in the framework of the pre-existing literature. Both the geomorphological coherence of the calculated Wi and the results of the validation procedure suggested a good reliability of the method, which is also relatively easy to apply and update.

Landslide processes and Andosols: the case study of the Campania region, Italy

Most catastrophic mudslides in Campania are related to soils developing upon pyroclastic materials covering carbonatic relieves of the Campanian Apennines. The soil observed in the detachment crowns of the investigated fast mudflow consisted of fertile Andosols (generally Hapludands and Udivitrands) that were very sensitive to anthropic or natural changes. This is due to the unique chemical, physical, morphological and hydrological behaviour of these soils, including (i) high water retention near saturation, (ii) high hydraulic conductivity, (iii) high smeariness of most horizons, and (iv) high vertical and lateral variability of the properties of the soil horizons. Aspect is important in determining soil susceptibility to landslide triggering and landslide susceptibility is related to hydrological properties that induce higher water storage especially in northern aspect soils. It is clear that stability of these soils requires conservation, implemented through appropriate forest planning and management. Improved risk management policies are necessary to preserve soil continuity and to decrease the risk both of surface soil erosion and to human lives and infrastructure.

Soil erosion susceptibility maps of the Janare Torrent Basin (Southern Italy)

Abstract Please click here to download the map associated with this article. Soil erosion susceptibility mapping provides a classification of the land surface into zones each of which has a different likelihood, or risk, of experiencing specific soil erosion processes. Such maps are fundamental to land-use planning aimed at the conservation of soil resources. In this paper, 1:46,500 scale maps showing susceptibility to different soil erosion processes (sheet/rill erosion, gully erosion and landslide-induced mass erosion) are presented. The study was carried out in the 10.5 km2 Janare Torrent basin, located in Southern Italy. The basin was first characterized by lithology, morphology and land-use. Landslides, gullies and landsurfaces affected by intense sheet and/or rill erosion were then surveyed and mapped by integrating the analysis of aerial photos and topographic maps with field observations. Using ArcView GIS 3.2, the densities of each type of erosional landform in each lithological, slope, aspect and land-use class were obtained by means of intersection procedures. From densities, weights expressing the susceptibility to soil erosion of each class were calculated using bivariate statistical analysis. The thematic maps were then reclassified according to the calculated weights and overlaid using a GIS, thus calculating the soil erosion susceptibility value for each point in the study area. The ranges of susceptibility values were subdivided into four classes to produce the final susceptibility maps. The procedure is based on the processing of directly surveyed, mapped and interpreted data, is easy to apply, allows frequent updating of the susceptibility assessment, and is scientifically reliable.

Assessing the planform changes of the Tammaro River (southern Italy) from 1870 to 1955 using a GIS-aided historical map analysis

Most part of the vast scientific literature dealing with channel adjustments focuses on the period between the second half of the twentieth century and nowadays, when most of the adjustments occurred and data availability is generally great. On the contrary, few studies were carried out on older adjustments, notwithstanding their analysis is fundamental to fully understand both more recent evolutionary trends and the role possibly played by human disturbances. The lack of studies on older adjustments is total for rivers located in southern Italy. The present study attempts to partly fill this gap. An analysis of the planform changes experienced by Tammaro R. between 1870 and 1955 was carried out by means of a detailed GIS-aided analysis of historical maps. The results were interpreted in the framework of the pre-existing geomorphological, geographical and socio-economic literature. This latter highlighted that the Tammaro R. basin in the studied period was scarcely inhabited and almost un-anthropized, especially in the first part of the studied period. Between 1870 and 1909, the river underwent a slight and quite inhomogeneous widening and moderate increase in fluvial bars, together with a slight straightening and shortening, but without substantial changes in channel morphology, which was single-thread. Between 1909 and 1955, the river experienced a homogeneous and marked widening, increase in sinuosity and lengthening, together with a strong increase in fluvial bars, and the channel morphology drastically changed from single-thread to transitional. This trend was opposite to that of most rivers in that period, possibly because of the scarce human impact on both the Tammaro R. and its basin.

Geomorphology of the Lower Calore River alluvial plain (Southern Italy)

ABSTRACT A 1:18,000-scale geomorphological map of the Lower Calore River alluvial plain (Southern Italy) is here presented. The area strongly suffered the dramatic effects of a destructive flood on 15 October 2015. The presented Map was produced in a GIS using topographic maps dating from 1870, 1909, 1936 and 1955 and 1:10,000-scaled colour orthophotos from 1998. All the maps and aerial photos were georeferenced in the UTM33 WGS84 coordinate system. The detected landforms were manually digitized and checked in the field. A geodatabase containing attributes such as type, age and surface area of each landform was created and progressively updated. The areal and unconventional map legend was designed to provide maximum readability. In the alluvial plain, five orders of river terraces were recognized. They are separated by strongly reshaped, gently sloping, inactive fluvial scarps (FS), less than 1.5 m high. Former channels, now abandoned, were also mapped. The confluence migrated eastward/east-northeastward between 1870 and 1955, followed by a north-northwestward migration between 1955 and 1998. Finally, numerous riverbank failures were observed and mapped along the active FS. A secondary map showing the age of the alluvial plain was also produced and showed that most of the investigated alluvial plain formed between 1909 and 1936. The study also shows the results of channel adjustments experienced by the river in ∼130 years.

The flood event in Benevento on 14th-15th October 2015: a short reportEnvironmental pollution along the Ionian Coast in Punta Alice area, Cirò Marina (Kr), Italy: preliminary results

This report describes the flooding features caused by an unusual weather event. This event was characterized by severe rainfall that occurred between 14th and 15th October 2015 in Benevento and the surrounding areas. Extensive damage affected populated areas due to the overflow of the Calore River and its tributaries.

The Coastal Landscape of Cilento (Southern Italy): A Challenge for Protection and Tourism Valorisation

A striking coastline, about 100 km long, characterizes the southernmost part of the Campania region. It is comprised within one of the largest National Parks of Italy, named “Cilento, Vallo di Diano and Alburni Park”. The coast preserves a great number of geological and geomorphological features, frequently well integrated with anthropic structures, which makes it a unique landscape. The morphology of the coastal area of the Park is characterized by hills sloping down to the sea, where alternate bays with small beaches and rocky headlands, hosting a large number of Norman-Aragonese watchtowers. Limestone cliffs display impressive karst landforms, such as caves, which have undoubtedly favoured human presence since the Middle Paleolithic. In this suggestive landscape several landforms and deposits permit to reconstruct the Quaternary-aged sea-level changes.

Morphotectonic features of the Tammaro River basin, Southern Apennines, Italy

In this paper, the preliminary results of a research aimed to reconstruct the morphotectonic framework of the Tammaro River basin are presented. The use of dedicated geographic information systems (GIS) enabled an efficient managing and processing of heterogeneous datasets, produced using GIS-aided classical techniques of geological and geomorphological analysis of the relief. On these data, advanced statistical processing procedures were carried out. The Tammaro R. basin corresponds to a sector of the Southern Apennines experiencing a general SW–NE extension, with several evidence of recent seismicity, and looks very similar to other intermontane basins hosted along the axis of the Apennines. The basin is dominated by NE–SW striking faults that seem to be the key structures for the morphotectonic evolution of the area. NW–SE, N–S and E–W azimuthal sets of faults are also well represented and seem to have played a minor role. The existence of these faults is confirmed by clear geomorphological evidence, such as fluvial elbows, subsequent reaches of streams, straight slopes shaped as triangular or trapezoidal facets, fault scarps and displacements of five orders of palaeosurfaces.