Risk provision using field spectroscopy to identify spectral regions for the detection of defects in flexible pavements

Natural and physical hazards accelerate the deterioration of asphalted surfaces. Climatic factors are unavoidable and can affect the properties of asphalt mixtures, making them weaker and less durable. Thus, continuous monitoring of bituminous surfaces is something that can reduce the risks of public health. Remote sensing techniques have become an effective, noninvasive method for early detection of damaged asphalt pavements. This paper outlines a range of different remote sensing methodologies that can be used to monitor asphalt road pavements. This is complemented by the use of field spectroscopy for the examination of asphalt pavements of varying age and conditions. The results of the study found spectral differences regarding asphalt defects, such as physical cracking, patched cracking and polishing. These spectral changes were examined through “in-band” simulation analysis of the Landsat 7 ETM+ sensor, using appropriate relative spectral response filters, concluding that the ratio band 5/band 1 can be used to distinguish asphalt pavements of different date of construction and condition.     

Geography of crime in a Brazilian context: an application of social disorganization theory

Geography of crime research dates back to the early 1800s, most of which in English and in the context of the United States and Europe, but with a growing and significant literature studying the developing world. We contribute to this literature through an application of social disorganization theory in a Latin American context: Campinas, Brazil. We consider a number of property and violent crime types using census tracts as the spatial unit of analysis. Implementing a spatial regression method, we find support for social disorganization theory, but not as strong as similar studies in Europe and North America. However, because of the context of Campinas, Brazil, a different understanding of the local conditions proves to be important for understanding the geography of crime in this context. The implications of these results are discussed in the context of theoretical developments as well as crime prevention initiatives.     

Analysis of precipitation extremes based on satellite (CHIRPS) and in situ dataset over Cyprus

A study of a daily precipitation database for the island of Cyprus is performed for a period of 30 years. A number of climatic indices for precipitation are calculated using the recently available CHIRPS dataset, on high spatial (0.05°) and temporal (daily) resolution. The same parameters for the same time period (1981–2010) are then calculated using the dense network of rain gauges of the Cyprus Department of Meteorology. The results show a quite promising performance regarding indices related to daily precipitation thresholds, resulting in high correlation scores. In the case of indices referring to number of days, it seems that the results are ambiguous, with medium or no correlation, probably related to the criteria used for the identification of a wet (rainy) day on the CHIRPS dataset.     

Combining multivariate statistical analysis with geographic information systems mapping: a tool for delineating groundwater contamination

Multivariate Statistical Analysis (MSA) has successfully been coupled with geographic information system (GIS) mapping tools to delineate zones of aquifer contamination potential. While delineating contaminants is key to site remediation, it is often compromised by a poor understanding of hydrogeologic conditions, and by uncertainties in contaminant observations. MSA provides improved estimates of contamination potential by augmenting observed contaminant concentrations with auxiliary information from other water-quality parameters. GIS is useful for organizing and managing water-quality information by visually communicating large amounts of information. The proposed method first establishes appropriate areal extents, GIS coverages, and scales for displaying groundwater contamination concentrations of tritium and the volatile organic contaminants trichloroethylene (TCE) and tetrachloroethylene (PCE) at the Savannah River Site, South Carolina, USA. Principal components analysis is used to group variables that are most indicative of contamination potential. Tritium contamination potential is best represented as the combination of tritium with the cations Al, Mg, Na and total dissolved solids, while PCE contamination potential is predicted using PCE and Cl. Maps of contamination potentials for 1993–1995 geochemical data compare favorably with measured contaminant concentrations during 1999. Cluster analysis of water-quality data groups geochemical and contaminant concentrations into zones of homogeneous behavior.

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Resumen El Análisis Estadístico Multivariado (AEM) se ha acoplado con éxito con herramientas cartográficas del Sistema de Información Geográfico (SIG), para delinear zonas de potencial contaminación de acuíferos. En tanto que la delimitación de contaminantes es importante para recuperación del sitio, ella está a menudo amenazada por una comprensión pobre de las condiciones hidrogeológicas, y por las incertidumbres en las observaciones del contaminante. El AEM proporciona estimaciones mejoradas de contaminación potencial al aumentar las concentraciones observadas del contaminante, con la información auxiliar de otros parámetros de calidad de agua. El SIG es útil para organizar y manejar la información de calidad de agua, a través de la comunicación visual de cantidades grandes de información. El método propuesto establece primero magnitudes de área apropiadas, el área cubierta por el SIG, y las escalas para mostrar las concentraciones de contaminación del agua subterránea, a partir de tritio y de contaminantes orgánicos volátiles como tricloroetileno (TCE) y tetracloroetileno (PCE) en el sitio del Río al Savannah, Carolina del Sur, EE.UU. El análisis de componentes principales se usa para agrupar variables que son más indicativas de contaminación potencial. El potencial de contaminación Tritio, se representa mejor como la combinación de tritio con los cationes Al, Mg, Na y los sólidos disueltos totales, mientras la contaminación potencial de PCE se predice usando PCE y Cl. Los mapas de potenciales de contaminación para los datos geoquímicos de 1993–1995 se comparan favorablemente con las concentraciones medidas del contaminante durante 1999. El análisis de racimo hecho en datos de calidad de agua, agrupa concentraciones geoquímicas y concentraciones del contaminante en las zonas de comportamiento homogéneo.

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Résumé L’Analyse Statistique Multivariée (ASM) a été couplée avec succès avec les outils cartographiques des Sytèmes d’Information Géographique (SIG), afin de délimiter les zones à potentiel de contamination des aquifères. Alors que la connaissance de l’extension des contaminants est primordiale pour la réhabilitation des sites, elle est fréquemment compromise par une compréhension limitée du contexte hydrogéologique, et par les incertitudes sur l’observation des contaminants. L’ASM fournit une meilleure estimation du potentiel de contamination, en complétant les concentrations observées en contaminants par des informations annexes issues d’autres paramètres qualitatifs. Les SIG, par leurs capacités à conjuguer visuellement de grandes quantités d’information, sont utiles pour organiser et gérer les informations sur la qualité de l’eau. La première étape de la méthode proposée consiste à définir les limites spatiales appropriées, les couvertures SIG, ainsi que les échelles de visualisation des concentrations en contaminants des eaux souterraines, soit le tritium et les composés organiques volatiles trichloroéthylène et tetrachloroéthylène, sur le site de la rivière Savannah (Californie du Sud, USA). L’analyse en composantes principales est utilisée afin de regrouper les variables caractérisant de manière optimale le potentiel de contamination. Le potentiel de contamination en tritium est représenté le plus significativement par la combinaison du tritium, des cations Al, Mg et Na, et des solides dissous totaux (TDS). Le potentiel de contamination en tétrachloroéthylène est quant à lui estimé en utilisant le tetrachloroéthylène et Cl. Les cartes des potentiels de contamination établies sur les données géochimiques de la période 1993–1995 renvoient une image comparable aux concentrations en contaminants effectivement mesurées en 1999. Une analyse de groupement des données sur la qualité de l’eau rassemble les concentrations géochimiques et en contaminants dans des zones aux comportements homogènes.