Gaia Righini

Updating landslide inventory maps using Persistent Scatterer Interferometry (PSI)

This work illustrates the contribution of persistent scatterer interferometry (PSI) from radar satellites ERS (European Remote Sensing satellite) and ENVISAT (Environmental Satellite) for the updating of a pre-existing landslide inventory (LSI) map: the main purpose is to change or confirm the landslide state of activity and geometry and to identify new landslides. Radar data have been integrated with optical images and ancillary data in a 1320 km2 wide river basin (Biferno Basin) located in the central-eastern part of Italy. The geological setting of the area is characterized by clay and alternated clayey, silt and sandy formations that are affected by slow landslides. Field validation confirmed the results and the capabilities of multi-interferometric synthetic aperture radar data, integrated and coupled with conventional techniques, to support landslide investigation at the regional scale thanks to the available archive of repeated satellite data, which provides measurements of ground displacements with a millimetre-scale accuracy. In the study area, about 9% of the pre-existing LSI has been modified by means of permanent scatterer (PS) information, 15% of which have changed the state of activity from dormant to active and 95 new landslides were detected. The radar interpretation method applied in Biferno Basin confirms its high capability of detecting and mapping landslides at basin the scale: the information acquired from radar interpretation is the basis of the proposed method to evaluate the state of activity and the intensity of slow landslides. However, it is clear that limitations exist and this method does not always support the updating of LSI for the whole study area. We consider this methodology and procedure as a portable and suitable one for different geological and geomorphological environments.

Remote sensing techniques using Landsat ETM+ applied to the detection of iron ore deposits in Western Africa

Remote sensing methods enable the rapid and inexpensive mapping of surface geological and mineralogical features. This capability proves highly useful when working on isolated or inaccessible areas. In this study, several enhancements of Landsat Enhanced Thematic Mapper plus (i.e. band ratios, false colour composites and principal component analysis) were used and evaluated to obtain the best possible visualisation of iron deposits hosted in the Devonian sedimentary rocks of northwestern Africa. In particular, two test sites were chosen: southern Algeria (Djebilet area), where the literature mineralogical and geological data on iron mine fields were already available, and the Western Sahara (the southern flank of Tindouf Basin), which was investigated during a field campaign and was where the occurrence of an analogous sedimentary succession led us to hypothesise the possible presence of exploitable iron deposits. This work demonstrates the usefulness of multispectral imagery in the detection of iron-rich areas and establishes a full remote sensing procedure, which can be profitably applied to a wider region of Western Sahara and can provide interesting perspectives on the possibility of detecting new exploitable iron ore deposits in arid environments.

Unsustainable use of groundwater resources in agricultural and urban areas: a persistent scatterer study of land subsidence at the basin scale

Multi-temporal analysis of space-borne radar images through Persistent Scatterer Interferometry (PSI) is exploited for mapping subsidence at basin scale in the Gioia Tauro plain (Italy), a densely urbanized coastal area whose land deformation are controlled by aquifer overexploitation. Both historical (1992– 2001; ERS1/2 images) and present (2002-2006; ENVISAT images) scenarios are analyzed to solve the spatial variability and temporal evolution of ground displacements affecting the plain. Average deformation rates as high as 10– 15 mm/yr are observed from 1992 to 2006, with highest velocities (i.e. 22.8 mm/yr) occurred between 1992 and 2000 within the central part of the basin, in the area of Rizziconi (5 km ESE of Gioia Tauro). The outcomes of this PSI study will support the future improvement of groundwater management and the implementation of best strategies for risk mitigation, land use planning, sustainable use of groundwater resources, and consequent reduction of economic and social impacts.

Assessing the Capabilities of VHR Satellite Data for Debris Flow Mapping in the Machu Picchu Area (C101-1)

Machu Picchu is an ancient Inca city located on a narrow ridge, within the Andes, approximately 80 km north-west of Cusco, Peru. This site of exceptional cultural heritage and its related infrastructure are being undermined by rapid debris flows, that are related to the presence of thick debris deposits produced by granite weathering, past slides and climatic conditions. On 26 December 1995 a rock fall/debris flow occurred on the road that leads to the citadel (Carretera Hiram Bingham) interrupting the traffic coming from the railway station of Aguas Calientes, and on 10 April 2004 a major debris flow, channeled in the Alcamayo stream, devastated the village of Aguas Calientes, causing 11 casualties and damaging the railway. Within the framework of the International Consortium on Landslides (ICL) a program of monitoring the instability conditions at this site was undertaken. In this work the preliminary results of the field survey and the analysis of some very high resolution (VHR) satellite images are presented. A multi-temporal analysis of Quickbird satellite (from Digitalglobe©) panchromatic and multispectral data was carried out: an archive image dated 18 June 2002 was available while a new acquisition with a good image was obtained on 18 May 2004. The main purpose of the analysis was the reconnaissance of debris flows using remote sensing techniques. The remote sensing data analysis was integrated with a field survey, carried out in September 2004. This allowed us to confirm the interpretation of the images, to produce a detailed geomorphological map of the area around the Carretera Hiram Bingham and to assess the thickness of debris deposits on the slopes. The results constitute a first step towards a complete debris flow hazard assessment in the area, where the interactions between slope instability and land use can produce very critical conditions.

Study of the Impact of Low vs. High Resolution Meteorology on Air Quality Simulations Using the MINNI Model Over Italy

Modelling air quality requires the description of a large number of processes interacting each other. In order to properly model concentrations of atmospheric pollutants it is crucial to have a realistic reproduction of meteorological parameters, which can be critical in areas presenting a complex orography like the Italian peninsula. This work shows an analysis of the results obtained with the national model MINNI at two different horizontal resolutions (20 and 4 km), for a whole year over Italy. Comparisons between modelled and observed temperature and pollutants concentrations are carried out. The prediction of temperature is improved with the increase of model spatial resolution, as it is for pollutants like NO2 and CO, while the improvement is not always evident for O3 concentrations. Results are discussed providing an interpretation of the observed features.

Mapping air pollutants at municipality level in Italy and Spain in support to health impact evaluations

A growing health concern, due to poor air quality, recently led to an increased number of studies regarding air pollution effects on public health. Consequently, close attention is paid to estimation methods of exposure to atmospheric pollutants. This paper aims to meet a specific requirement of epidemiological researchers, that is providing annual air pollution maps at municipality scale for health impact assessment purposes on national basis. Firstly, data fusion through kriging with external drift is implemented, combining pollution data from two different sources, models and measurements, in order to improve the spatial distribution of surface concentrations at grid level. Then, the assimilated data of air pollution are upscaled, so as to obtain concentrations at municipality level. This methodology was applied to Italy and Spain (in Spain, only the second step was carried out since the modeled concentration already included an assimilation procedure). In both countries, for each municipality, an estimate of the concentration value for atmospheric pollutants of major concern for human health (PM10 and NO2) was provided, offering more relevant information from a surveillance point of view.

Application of a Land Cover Indicator to Characterize Spatial Representativeness of Air Quality Monitoring Stations Over Italy

In order to achieve a cost-effective control of air quality in one region and to evaluate effects on population of long term exposure to air pollution, the assessment of spatial representativeness of air quality monitoring stations is of fundamental relevance. In this work, the area of representativeness has been assessed by means of a synthetic indicator describing the dependency of concentration on land cover distribution. The rationale is that, the more variable is the indicator in the surroundings of the station, the less representative are the concentrations measured at the air quality station in the surroundings. Pollutants under investigation were PM2.5 and O3 and the CORINE land cover map of 2006 was used with ad hoc modifications. The variability of the indicator was explored within circular buffers around the sites, with increasing radii resulting below the established threshold of 20 % for almost all cases. Results showed that the methodology allows an useful and quick assessment of spatial representativeness of a monitoring site, without the need of dedicated measurement campaigns.

Remote Sensing And GIS As Tools For The Hydro-geomorphological Modeling Of Soil Erosion In Semi-arid Mediterranean Regions

2 3 Abstract This contribution highlights the advantages of using a multidisciplinary modelling approach to the characterisation of the environmental dynamics of a typical semi-arid Mediterranean region, the Flumendosa river basin located in central Sardinia (Italy). Here, the widespread presence of geomorphological active processes interacts with the consequences of intense human activities on crop cultivation and forest management to produce a fragile environment the equilibrium of which must be carefully surveyed and maintained. To this end, an hydro-geomorphological soil erosion hazard model was devised and applied using remote sensing and G.I.S. techniques as support tools. Radiometric enhancement and supervised classification processing of multitemporal Landsat TM images were used to derive land cover mformation, allowing to understand the seasonal evolution of the area and to monitor the presence and movement of organic materials. These data were then combined with those derived from ground truth and ground survey campaigns concerning geology and geomorphology. At the same time, rainfall simulations were carried out in order to evaluate the principal parameters involved in the soil erosion processes. On these data a hydro-geomorphological model based on the spatial prevalence of the different erosion processes, was applied. Six main parameters (i.e. soil erosivity, land use, hillslope gradient and curvature, contributing area and soil infiltration capacity) were used and combined with a matrix linear combination. Results show that the model could represent, if routinely applied at a local administrative level, a valuable tool for forecasting the relative risk of soil erosion in the framework of a correct environmental management.

Ground deformation and associated hazards in NW peloponnese (Greece)

ABSTRACT In the last decades, ground deformations were investigated, analysed and monitored using several methods. As a consequence of a spreading urbanization, several phenomena, e.g. landslide and subsidence, were emphasized or triggered causing not only socio-economic damages, but, in some cases, also casualties. The investigation and mapping of these phenomena are important for both local authorities and civil protection in order to promote a higher conscientious urban planning and to highlight the more hazardous areas. Furthermore, the information are a key point for social development connected to the awareness of the environment and the related risk. The Achaia prefecture, in the north-eastern Peloponnese (Greece), close to the Gulf of Patras, is an area strongly affected by subsidence and landslides. Furthermore, this is an earthquake-prone area, a factor that can trigger some mass movements. For this region, a landslide inventory was realized with the help of the interpretation of Persistent Scatterers data, for the period 1992–2008, and high-resolution optical satellite images, available until 2016, in addition to the investigation of the landslide State of Activity. Moreover, for the coastal area, a section was investigated to evidence subsidence.

M-TraCE: a new tool for high-resolution computation and statistical elaboration of backward trajectories on the Italian domain

Air backward trajectory calculations are commonly used in a variety of atmospheric analyses, in particular for source attribution evaluation. The accuracy of backward trajectory analysis is mainly determined by the quality and the spatial and temporal resolution of the underlying meteorological data set, especially in the cases of complex terrain. This work describes a new tool for the calculation and the statistical elaboration of backward trajectories. To take advantage of the high-resolution meteorological database of the Italian national air quality model MINNI, a dedicated set of procedures was implemented under the name of M-TraCE (MINNI module for Trajectories Calculation and statistical Elaboration) to calculate and process the backward trajectories of air masses reaching a site of interest. Some outcomes from the application of the developed methodology to the Italian Network of Special Purpose Monitoring Stations are shown to assess its strengths for the meteorological characterization of air quality monitoring stations. M-TraCE has demonstrated its capabilities to provide a detailed statistical assessment of transport patterns and region of influence of the site under investigation, which is fundamental for correctly interpreting pollutants measurements and ascertaining the official classification of the monitoring site based on meta-data information. Moreover, M-TraCE has shown its usefulness in supporting other assessments, i.e., spatial representativeness of a monitoring site, focussing specifically on the analysis of the effects due to meteorological variables.