Biagio Di Mauro

Cryoconite as a temporary sink for anthropogenic species stored in glaciers

Cryoconite, the typical sediment found on the surface of glaciers, is mainly known in relation to its role in glacial microbiology and in altering the glacier albedo. But if these aspects are relatively well addressed, the same cannot be said about the geochemical properties of cryoconite and the possible interactions with glacial and peri-glacial environment. Current glacier retreat is responsible for the secondary emission of species deposited in high-altitude regions in the last decades. The role played by cryoconite in relation to such novel geochemical fluxes is largely unknown. Few and scarce observations suggest that it could interact with these processes, accumulating specific substances, but why, how and to what extent remain open questions. Through a multi-disciplinary approach we tried to shed lights. Results reveal that the peculiar composition of cryoconite is responsible for an extreme accumulation capability of this sediment, in particular for some, specific, anthropogenic substances.

Surface Reflectance and Sun-Induced Fluorescence Spectroscopy Measurements Using a Small Hyperspectral UAS

This study describes the development of a small hyperspectral Unmanned Aircraft System (HyUAS) for measuring Visible and Near-Infrared (VNIR) surface reflectance and sun-induced fluorescence, co-registered with high-resolution RGB imagery, to support field spectroscopy surveys and calibration and validation of remote sensing products. The system, namely HyUAS, is based on a multirotor platform equipped with a cost-effective payload composed of a VNIR non-imaging spectrometer and an RGB camera. The spectrometer is connected to a custom entrance optics receptor developed to tune the instrument field-of-view and to obtain systematic measurements of instrument dark-current. The geometric, radiometric and spectral characteristics of the instruments were characterized and calibrated through dedicated laboratory tests. The overall accuracy of HyUAS data was evaluated during a flight campaign in which surface reflectance was compared with ground-based reference measurements. HyUAS data were used to estimate spectral indices and far-red fluorescence for different land covers. RGB images were processed as a high-resolution 3D surface model using structure from motion algorithms. The spectral measurements were accurately geo-located and projected on the digital surface model. The overall results show that: (i) rigorous calibration enabled radiance and reflectance spectra from HyUAS with RRMSE < 10% compared with ground measurements; (ii) the low-flying UAS setup allows retrieving fluorescence in absolute units; (iii) the accurate geo-location of spectra on the digital surface model greatly improves the overall interpretation of reflectance and fluorescence data. In general, the HyUAS was demonstrated to be a reliable system for supporting high-resolution field spectroscopy surveys allowing one to collect systematic measurements at very detailed spatial resolution with a valuable potential for vegetation monitoring studies. Furthermore, it can be considered a useful tool for collecting spatially-distributed observations of reflectance and fluorescence that can be further used for calibration and validation activities of airborne and satellite optical images in the context of the upcoming FLEX mission and the VNIR spectral bands of optical Earth observation missions (i.e., Landsat, Sentinel-2 and Sentinel-3).

Author Correction: Cryoconite as a temporary sink for anthropogenic species stored in glaciers.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Classifying zones of suitability for manual drilling using textural and hydraulic parameters of shallow aquifers: a case study in northwestern Senegal

A method is proposed that uses analysis of borehole stratigraphic logs for the characterization of shallow aquifers and for the assessment of areas suitable for manual drilling. The model is based on available borehole-log parameters: depth to hard rock, depth to water, thickness of laterite and hydraulic transmissivity of the shallow aquifer. The model is applied to a study area in northwestern Senegal. A dataset of boreholes logs has been processed using a software package (TANGAFRIC) developed during the research. After a manual procedure to assign a standard category describing the lithological characteristics, the next step is the automated extraction of different textural parameters and the estimation of hydraulic conductivity using reference values available in the literature. The hydraulic conductivity values estimated from stratigraphic data have been partially validated, by comparing them with measured values from a series of pumping tests carried out in large-diameter wells. The results show that this method is able to produce a reliable interpretation of the shallow hydrogeological context using information generally available in the region. The research contributes to improving the identification of areas where conditions are suitable for manual drilling. This is achieved by applying the described method, based on a structured and semi-quantitative approach, to classify the zones of suitability for given manual drilling techniques using data available in most African countries. Ultimately, this work will support proposed international programs aimed at promoting low-cost water supply in Africa and enhancing access to safe drinking water for the population.RésuméUne méthode est. proposée utilisant l’analyse des logs stratigraphiques des forages pour la caractérisation des aquifères peu profonds et pour l’évaluation des zones favourable pour le forage manuel. Le modèle repose sur l’analyse des paramètres extraits des logs de forage disponibles: profondeur au socle, profondeur au niveau piézométrique, épaisseur de la latérite et transmissivité hydraulique de l’aquifère peu profond. Le modèle est. appliqué à une zone d’étude dans le nord-ouest du Sénégal. Un ensemble de données de logs de forages a été traité en utilisant l’application informatique TANGAFRIC développée au cours de la recherche. Après une procédure manuelle pour attribuer une catégorie standardisée décrivant les caractéristiques lithologiques, l’étape suivante et une extraction automatique des différents paramètres texturaux et l’estimation de la conductivité hydraulique en utilisant des valeurs de référence disponibles dans la littérature. Les valeurs de conductivité hydraulique estimées à partir des données stratigraphiques ont été partiellement validées, en les comparant aux valeurs mesurées à partir d’une série de pompages d’essais réalisés sur des forages de grand diamètre. Les résultats indiquent que cette méthode permet de produire une interprétation fiable du contexte hydrogéologique peu profond en utilisant des informations généralement disponibles dans la région. La recherche contribue à améliorer l’identification de régions pour lesquelles des conditions sont en faveur de forages manuels. Ceci est. réalisé en appliquant la méthode décrite, basée sur une approche structurée et semi-quantitative, pour classer l’aptitude de zones à des techniques données de forage manuel en utilisant les données disponibles dans la plupart des pays africains. En fin de compte, ce travail appuiera les programmes internationaux proposés visant à promouvoir l’approvisionnement en eau potable à un faible coût en Afrique et à améliorer l’accès à l’eau potable pour la population.ResumenSe propone un método que utiliza el análisis de registros estratigráficos de pozos para la caracterización de acuíferos poco profundos y para la evaluación de áreas aptas para la perforación manual. El modelo se basa en el análisis de parámetros extraídos de registros de pozos disponibles: profundidad de la roca dura, profundidad del agua, espesor de laterita y transmisividad hidráulica del acuífero poco profundo. El modelo se aplica a un área de estudio en el noroeste de Senegal. Un conjunto de datos de registros de perforaciones se ha procesado utilizando un paquete de software (TANGAFRIC) desarrollado durante la investigación. Después de un procedimiento manual para asignar una categoría estándar que describe las características litológicas, el siguiente paso es la extracción automatizada de diferentes parámetros texturales y la estimación de la conductividad hidráulica usando los valores de referencia disponibles en la literatura. Los valores de conductividad hidráulica estimados a partir de datos estratigráficos han sido parcialmente validados, comparándolos con valores medidos de una serie de ensayos de bombeo realizados en pozos de gran diámetro. Los resultados muestran que este método es capaz de producir una interpretación confiable del contexto hidrogeológico superficial usando información generalmente disponible en la región. La investigación contribuye a mejorar la identificación de áreas donde las condiciones son aptas para la perforación manual. Esto se logra aplicando el método descrito, basado en un enfoque estructurado y semicuantitativo, para clasificar la idoneidad para determinadas técnicas de perforación manual utilizando datos disponibles en la mayoría de los países africanos. En última instancia, este trabajo apoyará los programas internacionales propuestos para promover el suministro de agua a bajo costo en África y mejorar el acceso al agua potable para la población.摘要提出了一种利用井孔地层测井资料分析浅层含水层的分析方法,并对适合人工钻孔的区域进行评估。该模型基于从可用井眼测井中提取的参数分析:浅层含水层深度与硬岩,水深,红土厚度和液压透过率。该模型适用于塞内加尔西北部的一个研究区域。钻孔日志的数据集已经使用研究期间开发的软件包(TANGAFRIC)进行处理。在指定描述岩性特征的标准类别的手动程序之后,下一步是使用文献中可用的参考值自动提取不同的结构参数和水力传导率的估计。通过与大直径井进行的一系列泵送试验的测量值进行比较,已经部分验证了从地层数据估算出的水力传导率值。结果表明,该方法能够利用该地区通用的信息,对浅层水文地质环境产生可靠的解释。该研究有助于改善条件适合手动钻孔的区域的识别。这是通过应用所描述的方法,基于结构化和半定量方法,使用大多数非洲国家可用的数据对给定的手动钻孔技术进行分类。最终,这项工作将支持旨在促进非洲低成本供水和提高人民获得安全饮用水的拟议国际方案。ResumoUm método é proposto usando análise estratigráfica de perfis de poços para a caracterização de aquíferos rasos e avaliação de áreas favoráveis para perfuração manual. O modelo é baseado na análise dos parâmetros extraídos de perfis de poços disponíveis: profundidade da rocha dura, profundidade da água, espessura da laterita, e transmissividade hidráulica do aquífero raso. O modelo é aplicado a uma área de estudo no noroeste do Senegal. Os perfis dos poços foram processados usando o programa de computador (TANGAFRIC) desenvolvido durante a pesquisa. Após um procedimento manual para assinalar uma categoria padrão descrevendo as características litológicas, o próximo passo é a extração automática de diferentes parâmetros texturais e a estimativa da condutividade hidráulica usando os valores de referência disponíveis na literatura. Os valores de condutividade hidráulica estimados de dados de estratigrafia foram parcialmente validados comparando estes com valores medidos através de uma série de testes de bombeamento realizados em poços de grande diâmetro. Os resultados mostram que este método é capaz de produzir uma interpretação confiável do contexto hidrogeológico raso usando informações disponíveis na região. A pesquisa contribui para promover a identificação de áreas onde as condições são favoráveis para perfuração manual. Isso é obtido aplicando o método descrito, baseado no processo estruturado e semiquantitativo para classificar a favorabilidade para uma certa técnica de perfuração manual usando os dados disponíveis na maioria dos países Africanos. Por último, este trabalho suportará programas internacionais propostos com o objetivo de promover o abastecimento de água a baixo custo na África e aumentar o acesso seguro a água potável para a população.