Vincenzo Liguori

Integrated geomorphological mapping in the north-western sector of Agrigento (Italy)

The geomorphological map is an essential tool to perform a proper urban planning in mountainous or hilly areas. In this paper a multidisciplinary approach to derive a 1:2000 geomorphological map is described. The proposed methodology consists of the integration between aerial photographs, acquired in 2003, and four datasets of Persistent Scatterer Interferometry (PSI) measures to update a pre-existing landslide inventory. The integrated data were used to achieve a validated geomorphological map by means of a geomorphological survey. The study area is located in southern Italy (Agrigento, Sicily). The city of Agrigento, included in the World Heritage List of UNESCO in 1997, is located on the Girgenti hill which is exposed on its northern side, to several landslide phenomena. The top of the hill is characterized by the presence of part of the cultural heritage of the city and is affected by rockfalls, rock topples and shallow-seated landslides, representing a serious risk for important historical buildings. The results demonstrate the validity of this method to achieve a suitable tool in landscape and cultural heritage management.

Insar time-series analysis for management and mitigation of geological risk in urban area

This work shows the capabilities of InSAR time series analyses to support civil protection activities in the framework of geological risk management and mitigation. We discuss the outcomes from an integrated analysis of conventional in situ investigations and observations with advanced InSAR analyses carried out for the test sites of Agrigento and Naro (Italy), affected by ground instability respectively due to landsliding and tectonic forces. The study of past ground deformations provided valuable insights into the spatial and temporal patterns and behaviors of these phenomena, helping local civil protection authorities to focus resources on the areas of maximum need and to identify the most appropriate mitigation measures to reduce the impacts on elements at risk.

Landslide Impacts on Agrigento’s Cathedral Imaged with Radar Interferometry

ERS1/2 (1992–2000), ENVISAT (2002–2008) and RADARSAT1 (2003–2007) satellite data, processed with Persistent Scatterer Interferometry, are exploited to study the historic urban area of Agrigento, Italy, whose structural stability is threatened by retrogressive landslide processes. Up to 2–5mm/year of line-of-sight displacement are observed in 1992–2008 on the staircase and the left aisle of the Cathedral. Displacement acceleration to 13–15mm/year is measured in July 2006–May 2007, in the northern portion of the churchyard, in front of the left aisle. The areas moving at higher rates, located at the edge of the NW slope of Girgenti hill, correspond to those showing major structural damages. Aggravation of structural instability of the Cathedral and increased risk of collapses is observed in 2011.

Environmental Hazard And Water Quality:The River Platani Basin

The River Platani, situated in the western side of Sicily, is one of the greatest rivers of the island. It runs for about 103 Km and the basin extends to about 1,784.9 Km. It rises near Santo Stefano Quisquina (Ag); the river flows to Capo Bianco (Ag) ends in the Mediterranean Sea. The morphology of the basin is predominantly characterized by rises of modest entities with slopes sweet or calanques. In the containing gypsum and carbonatic stony heaps are diffused the karst phenomena. In the Platani basin some mines are located of rock salt and potassium salts; today the mines are closed after a long activity and they interact with the geomorphology of the territory and on the water quality of the river. An example is given by the ex mine “Muti-Coffari” (Ag), in fact the mine determines an evident incidence on the physical-chemical characteristics of the water and the fluvial ecosystem. Where the “sinkholes” are present, caused by the incessant thinning of the vault and pillars of the mine’s tunnel, meteoric water penetrates inside, flooding all the underground levels; the waters, through different chemical process, attach the evaporitics rocks and they have a concentration of salts. Consequently, because of the flooding of the tunnels, the saturated salt waters escape from the entrance of the mines to flow into the River Plantain. Through the monitoring of the principal branch of the River Platani it can be deduced that the river can be considered constituted by two separate ecosysystems: the first goes from the source to the point of immission of the small affluent coming from the mine; the second extended from the salt mine up to the mouth. Observing the graphs products on the chemical-physical parameters evident as the element of separation is constituted by the immission of saturated salt water. After the immission of the Torrente Salina, the values of the sulphates, of the chlorides, and of the sodium, sensitively increase. The environmental aspect that derives is a hyper saltiness that affects the fluvial ecosystem, as a matter of fact a desertification of fertile areas where once there were very fertile cultivations.