Natural hazards vs human impact: an integrated methodological approach in geomorphological risk assessment on the Tursi historical site, Southern Italy

Abstract

The Tursi-Rabatana historical site is very representative of the cultural heritage of Basilicata, Southern Italy. Morphological evolution of the landscape is characterized by very intense erosive phenomena such as landslides, deep gullies, rills, and piping, which affect the perimeter of urban settlements and threaten the conservation of these sites. Rainfalls and the lithology of the substratum are the main factors to which the landscape evolution is linked, triggering landslide and linear erosion phenomena. Climate analysis carried out during the last century showed an increasing trend in the rainfall intensity over extremely short periods. This condition also induced an increase in the vulnerability level of the slopes. Integrated analysis between territorial data (geology, geomorphology, climate) and historical documents showed that, at least from the last century, the geomorphological hazard has been accentuated by the intense human activity of cave excavation along several fronts under the present urban area. The geophysical investigation also permitted the mapping of shallow caves and tunnels in the subsurface reconstructing the multilevel complex hypogeal system. This work also produced evidence that the human interventions occurring during the historical period have been a determining factor in increasing the hazard level and accelerating the preexisting morphological processes.

Near surface geophysics techniques and geomorphological approach to reconstruct the hazard cave map in historical and urban areas

“…The lithology of the substratum (well-cemented sands, silt-clayey sands and subordinately sandy conglomerates) and rainfalls are the main factors to which the landscape evolution is linked. These represent the main determining elements for landslide triggering and linear erosion phenomena (Lazzari et al, 2006). In fact, morphological evolution of the sandy hillslopes on which Tursi town rises is characterized by very intense erosive phenomena such as landslides, deep gullies, rills, and piping, which affect the whole perimeter of urban settlements and threaten the conservation of these sites (Fig.…”

“…3). From the point of view of the process of physical degradation, the sandy facies are characterized by desiccation cracks to which the piping erosion and detachment blocks along the slopes are closely linked (Lazzari et al, 2006). In some cases large voids do not develop, but seepage erosion and running sand cause morphologically similar surface collapse phenomena (sinkholes).…”

“…The history of this settlement has always been deeply connected with the characteristics of the neighbouring environment and it seems possible that the first settlement was built by excavating the slopes of the sandy relief. It was a typical rupestrian settlement, where meteoric water was stored inside underground tank (cisterns) excavated on the slopes (Lazzari et al, 2006). During recent centuries, the increase in territory development by humans produced an increase in cave excavation in the Tursi-Rabatana urban area.…”

Changes in daily precipitation extremes in the Mediterranean from 1951 to 2010: the Basilicata region, southern Italy

“…The Basilicata region, an area extending for 9992 km 2 in southern Italy, is one of the most vulnerable regions over the national territory, in which nearly 50% of the towns are classified at high risk of landsliding or flooding (Clarke and Rendell, 2006;Lazzari et al, 2006;Lazzari, 2011). The area affected by flood risk is 260 km 2 (2.6% of the whole territory) and mainly includes the hilly areas and the coastal belt, which are exploited in agriculture, the main regional economic source (Piccarreta and Capolongo, 2009;Piccarreta et al, in press).…”

Geomorphological hazard analysis along the Egyptian Red Sea coast between Safaga and Quseir

“…Lazzari et al (2006) indicated that the integrated analysis between territorial data (geology, geomorphology and climate) and historical documents showed that the geomorphological hazard has been accentuated by the intense human activity. His work also produced evidence that the human interventions occurring during the historical period have been a determining factor in increasing the hazard level and accelerating the preexisting morphological processes.…”