An appropriate data set size for digital soil mapping in Erechim, Rio Grande do Sul, Brazil

Digital information generates the possibility of a high degree of redundancy in the data available for fitting predictive models used for Digital Soil Mapping (DSM). Among these models, the Decision Tree (DT) technique has been increasingly applied due to its capacity of dealing with large datasets. The purpose of this study was to evaluate the impact of the data volume used to generate the DT models on the quality of soil maps. An area of 889.33 km² was chosen in the Northern region of the State of Rio Grande do Sul. The soil-landscape relationship was obtained from reambulation of the studied area and the alignment of the units in the 1:50,000 scale topographic mapping. Six predictive covariates linked to the factors soil formation, relief and organisms, together with data sets of 1, 3, 5, 10, 15, 20 and 25 % of the total data volume, were used to generate the predictive DT models in the data mining program Waikato Environment for Knowledge Analysis (WEKA). In this study, sample densities below 5 % resulted in models with lower power of capturing the complexity of the spatial distribution of the soil in the study area. The relation between the data volume to be handled and the predictive capacity of the models was best for samples between 5 and 15 %. For the models based on these sample densities, the collected field data indicated an accuracy of predictive mapping close to 70 %.

Comparison between detailed digital and conventional soil maps of an area with complex geology

Since different pedologists will draw different soil maps of a same area, it is important to compare the differences between mapping by specialists and mapping techniques, as for example currently intensively discussed Digital Soil Mapping. Four detailed soil maps (scale 1:10.000) of a 182-ha sugarcane farm in the county of Rafard, São Paulo State, Brazil, were compared. The area has a large variation of soil formation factors. The maps were drawn independently by four soil scientists and compared with a fifth map obtained by a digital soil mapping technique. All pedologists were given the same set of information. As many field expeditions and soil pits as required by each surveyor were provided to define the mapping units (MUs). For the Digital Soil Map (DSM), spectral data were extracted from Landsat 5 Thematic Mapper (TM) imagery as well as six terrain attributes from the topographic map of the area. These data were summarized by principal component analysis to generate the map designs of groups through Fuzzy K-means clustering. Field observations were made to identify the soils in the MUs and classify them according to the Brazilian Soil Classification System (BSCS). To compare the conventional and digital (DSM) soil maps, they were crossed pairwise to generate confusion matrices that were mapped. The categorical analysis at each classification level of the BSCS showed that the agreement between the maps decreased towards the lower levels of classification and the great influence of the surveyor on both the mapping and definition of MUs in the soil map. The average correspondence between the conventional and DSM maps was similar. Therefore, the method used to obtain the DSM yielded similar results to those obtained by the conventional technique, while providing additional information about the landscape of each soil, useful for applications in future surveys of similar areas.

A new method to estimate the infilling of alluvial sediment of glacial valleys using a sloping local base level

A new method is used to estimate the volumes of sediments of glacial valleys. This method is based on the concept of sloping local base level and requires only a digital terrain model and the limits of the alluvial valleys as input data. The bedrock surface of the glacial valley is estimated by a progressive excavation of the digital elevation model (DEM) of the filled valley area. This is performed using an iterative routine that replaces the altitude of a point of the DEM by the mean value of its neighbors minus a fixed value. The result is a curved surface, quadratic in 2D. The bedrock surface of the Rhone Valley in Switzerland was estimated by this method using the free digital terrain model Shuttle Radar Topography Mission (SRTM) (~92 m resolution). The results obtained are in good agreement with the previous estimations based on seismic profiles and gravimetric modeling, with the exceptions of some particular locations. The results from the present method and those from the seismic interpretation are slightly different from the results of the gravimetric data. This discrepancy may result from the presence of large buried landslides in the bottom of the Rhone Valley.

Preliminary description and slope stability analyses of the 2008 Little Salmon lake and 2007 Mt. Steele landslides, Yukon

In August 2008, reactivation of the Little Salmon Lake landslide occurred. During this event, hundreds of conical mounds of variable size and composition formed in the deposition zone. The characteristics of these landforms are described and a potential mechanism for their formation is proposed. A preliminary slope stability analysis of the 2007 Mount Steele rock and ice avalanche was also undertaken. The orientation of very high persistence (>20 m long) structural planes (e.g., faults, joints and bedding) within bedrock in the source zone was obtained using an airborne-LiDAR digital elevation model and the software COLTOP-3D. Using these discontinuity orientation measurements, kinematic, surface wedge and simple three-dimensional distinct element slope stability analyses were performed.

Développement d'une méthode microgravimétrique urbaine : intégration dans un SIG et application au projet du M2 lausannois

Résumé La réalisation d'une seconde ligne de métro (M2) dès 2004, passant dans le centre ville de Lausanne, a été l'opportunité de développer une méthodologie concernant des campagnes microgravimétriques dans un environnement urbain perturbé. Les corrections topographiques prennent une dimension particulière dans un tel milieu, car de nombreux objets non géologiques d'origine anthropogénique comme toutes sortes de sous-sols vides viennent perturber les mesures gravimétriques. Les études de génie civil d'avant projet de ce métro nous ont fournis une quantité importante d'informations cadastrales, notamment sur les contours des bâtiments, sur la position prévue du tube du M2, sur des profondeurs de sous-sol au voisinage du tube, mais aussi sur la géologie rencontré le long du corridor du M2 (issue des données lithologiques de forages géotechniques). La planimétrie des sous-sols a été traitée à l'aide des contours des bâtiments dans un SIG (Système d'Information Géographique), alors qu'une enquête de voisinage fut nécessaire pour mesurer la hauteur des sous-sols. Il a été alors possible, à partir d'un MNT (Modèle Numérique de Terrain) existant sur une grille au mètre, de mettre à jour celui ci avec les vides que représentent ces sous-sols. Les cycles de mesures gravimétriques ont été traités dans des bases de données Ac¬cess, pour permettre un plus grand contrôle des données, une plus grande rapidité de traitement, et une correction de relief rétroactive plus facile, notamment lorsque des mises à jour de la topographie ont lieu durant les travaux. Le quartier Caroline (entre le pont Bessières et la place de l'Ours) a été choisi comme zone d'étude. Le choix s'est porté sur ce quartier du fait que, durant ce travail de thèse, nous avions chronologiquement les phases pré et post creusement du tunnel du M2. Cela nous a permis d'effectuer deux campagnes gravimétriques (avant le creu¬sement durant l'été 2005 et après le creusement durant l'été 2007). Ces réitérations nous ont permis de tester notre modélisation du tunnel. En effet, en comparant les mesures des deux campagnes et la réponse gravifique du modèle du tube discrétisé en prismes rectangulaires, nous avons pu valider notre méthode de modélisation. La modélisation que nous avons développée nous permet de construire avec détail la forme de l'objet considéré avec la possibilité de recouper plusieurs fois des interfaces de terrains géologiques et la surface topographique. Ce type de modélisation peut s'appliquer à toutes constructions anthropogéniques de formes linéaires. Abstract The realization of a second underground (M2) in 2004, in downtown Lausanne, was the opportunity to develop a methodology of microgravity in urban environment. Terrain corrections take on special meaning in such environment. Many non-geologic anthropogenic objects like basements act as perturbation of gravity measurements. Civil engineering provided a large amount of cadastral informations, including out¬lines of buildings, M2 tube position, depths of some basements in the vicinity of the M2 corridor, and also on the geology encountered along the M2 corridor (from the lithological data from boreholes). Geometry of basements was deduced from building outlines in a GIS (Geographic Information System). Field investigation was carried out to measure or estimate heights of basements. A DEM (Digital Elevation Model) of the city of Lausanne is updated from voids of basements. Gravity cycles have been processed in Access database, to enable greater control of data, enhance speed processing, and retroactive terrain correction easier, when update of topographic surface are available. Caroline area (between the bridge Saint-Martin and Place de l'Ours) was chosen as the study area. This area was in particular interest because it was before and after digging in this thesis. This allowed us to conduct two gravity surveys (before excavation during summer 2005 and after excavation during summer 2007). These re-occupations enable us to test our modélisation of the tube. Actually, by comparing the difference of measurements between the both surveys and the gravity response of our model (by rectangular prisms), we were able to validate our modeling. The modeling method we developed allows us to construct detailed shape of an object with possibility to cross land geological interfaces and surface topography. This type of modélisation can be applied to all anthropogenic structures.

Structural analysis of Turtle Mountain: Origin and influence of fractures in the development of rock slope failures

Large slope failures in fractured rocks are often controlled by the combination of pre-existing tectonic fracturing and brittle failure propagation in the intact rock mass during the pre-failure phase. This study focuses on the influence of fold-related fractures and of post-folding fractures on slope instabilities with emphasis on Turtle Mountain, located in SW Alberta (Canada). The structural features of Turtle Mountain, especially to the south of the 1903 Frank Slide, were investigated using a high-resolution digital elevation model combined with a detailed field survey. These investigations allowed the identification of six main discontinuity sets influencing the slope instability and surface morphology. According to the different deformation phases affecting the area, the potential origin of the detected fractures was assessed. Three discontinuity sets are correlated with the folding phase and the others with post-folding movements. In order to characterize the rock mass quality in the different portions of the Turtle Mountain anticline, the geological strength index (GSI) has been estimated. The GSI results show a decrease in rock mass quality approaching the fold hinge area due to higher fracture persistence and higher weathering. These observations allow us to propose a model for the potential failure mechanisms related to fold structures.

Grade and Cross Slope Estimation from LIDAR-based Surface Models, 2003

Many transportation agencies maintain grade as an attribute in roadway inventory databases; however, the information is often in an aggregated format. Cross slope is rarely included in large roadway inventories. Accurate methods available to collect grade and cross slope include global positioning systems, traditional surveying, and mobile mapping systems. However, most agencies do not have the resources to utilize these methods to collect grade and cross slope on a large scale. This report discusses the use of LIDAR to extract roadway grade and cross slope for large-scale inventories. Current data collection methods and their advantages and disadvantages are discussed. A pilot study to extract grade and cross slope from a LIDAR data set, including methodology, results, and conclusions, is presented. This report describes the regression methodology used to extract and evaluate the accuracy of grade and cross slope from three dimensional surfaces created from LIDAR data. The use of LIDAR data to extract grade and cross slope on tangent highway segments was evaluated and compared against grade and cross slope collected using an automatic level for 10 test segments along Iowa Highway 1. Grade and cross slope were measured from a surface model created from LIDAR data points collected for the study area. While grade could be estimated to within 1%, study results indicate that cross slope cannot practically be estimated using a LIDAR derived surface model.

Quantifying sediment storage in a high Alpine valley (Turtmanntal, Switzerland)

The determination of sediment storage is a critical parameter in sediment budget analyses. But, in many sediment budget studies the quantification of magnitude and time-scale of sediment storage is still the weakest part and often relies on crude estimations only, especially in large drainage basins (>100km2). We present a new approach to storage quantification in a meso-scale alpine catchment of the Swiss Alps (Turtmann Valley, 110km2). The quantification of depositional volumes was performed by combining geophysical surveys and geographic information system (GIS) modelling techniques. Mean thickness values of each landform type calculated from these data was used to estimate the sediment volume in the hanging valleys and the trough slopes. Sediment volume of the remaining subsystems was determined by modelling an assumed parabolic bedrock surface using digital elevation model (DEM) data. A total sediment volume of 781·3×106?1005·7×106m3 is deposited in the Turtmann Valley. Over 60% of this volume is stored in the 13 hanging valleys. Moraine landforms contain over 60% of the deposits in the hanging valleys followed by sediment stored on slopes (20%) and rock glaciers (15%). For the first time, a detailed quantification of different storage types was achieved in a catchment of this size. Sediment volumes have been used to calculate mean denudation rates for the different processes ranging from 0·1 to 2·6mm/a based on a time span of 10ka. As the quantification approach includes a number of assumptions and various sources of error the values given represent the order of magnitude of sediment storage that has to be expected in a catchment of this size.

Classification of textures seen from different distances and under varying illumination direction

Changes in the angle of illumination incident upon a 3D surface texture can significantly alter its appearance, implying variations in the image texture. These texture variations produce displacements of class members in the feature space, increasing the failure rates of texture classifiers. To avoid this problem, a model-based texture recognition system which classifies textures seen from different distances and under different illumination directions is presented in this paper. The system works on the basis of a surface model obtained by means of 4-source colour photometric stereo, used to generate 2D image textures under different illumination directions. The recognition system combines coocurrence matrices for feature extraction with a Nearest Neighbour classifier. Moreover, the recognition allows one to guess the approximate direction of the illumination used to capture the test image

Use of airborne laser scanner data in demanding forest conditions

Most of the applications of airborne laser scanner data to forestry require that the point cloud be normalized, i.e., each point represents height from the ground instead of elevation. To normalize the point cloud, a digital terrain model (DTM), which is derived from the ground returns in the point cloud, is employed. Unfortunately, extracting accurate DTMs from airborne laser scanner data is a challenging task, especially in tropical forests where the canopy is normally very thick (partially closed), leading to a situation in which only a limited number of laser pulses reach the ground. Therefore, robust algorithms for extracting accurate DTMs in low-ground-point-densitysituations are needed in order to realize the full potential of airborne laser scanner data to forestry. The objective of this thesis is to develop algorithms for processing airborne laser scanner data in order to: (1) extract DTMs in demanding forest conditions (complex terrain and low number of ground points) for applications in forestry; (2) estimate canopy base height (CBH) for forest fire behavior modeling; and (3) assess the robustness of LiDAR-based high-resolution biomass estimation models against different field plot designs. Here, the aim is to find out if field plot data gathered by professional foresters can be combined with field plot data gathered by professionally trained community foresters and used in LiDAR-based high-resolution biomass estimation modeling without affecting prediction performance. The question of interest in this case is whether or not the local forest communities can achieve the level technical proficiency required for accurate forest monitoring. The algorithms for extracting DTMs from LiDAR point clouds presented in this thesis address the challenges of extracting DTMs in low-ground-point situations and in complex terrain while the algorithm for CBH estimation addresses the challenge of variations in the distribution of points in the LiDAR point cloud caused by things like variations in tree species and season of data acquisition. These algorithms are adaptive (with respect to point cloud characteristics) and exhibit a high degree of tolerance to variations in the density and distribution of points in the LiDAR point cloud. Results of comparison with existing DTM extraction algorithms showed that DTM extraction algorithms proposed in this thesis performed better with respect to accuracy of estimating tree heights from airborne laser scanner data. On the other hand, the proposed DTM extraction algorithms, being mostly based on trend surface interpolation, can not retain small artifacts in the terrain (e.g., bumps, small hills and depressions). Therefore, the DTMs generated by these algorithms are only suitable for forestry applications where the primary objective is to estimate tree heights from normalized airborne laser scanner data. On the other hand, the algorithm for estimating CBH proposed in this thesis is based on the idea of moving voxel in which gaps (openings in the canopy) which act as fuel breaks are located and their height is estimated. Test results showed a slight improvement in CBH estimation accuracy over existing CBH estimation methods which are based on height percentiles in the airborne laser scanner data. However, being based on the idea of moving voxel, this algorithm has one main advantage over existing CBH estimation methods in the context of forest fire modeling: it has great potential in providing information about vertical fuel continuity. This information can be used to create vertical fuel continuity maps which can provide more realistic information on the risk of crown fires compared to CBH.

The uses of the outline for cultural formulation of the DSM-IV : from case conceptualization to treatment plan

ARTICLE 1 : RÉSUMÉ Amputation traumatique: Une étude de cas laotien sur l’indignation et l’injustice. La culture est un contexte essentiel à considérer pour produire un diagnostic et un plan d’intervention psychiatrique. Une perspective culturelle met en relief le contexte social dans lequel les symptômes émergent, et comment ils sont interprétés et gérés par la personne atteinte. Des études ethnoculturelles sur les maladies nous suggèrent que la plupart des gens nous donnent des explications pour leurs symptômes qui ont un fondement culturel. Bien que ces explications contredisent la théorie biomédicale, elles soulagent la souffrance des patients et leur permettent de donner une signification à cette dernière. L’exploration des caractéristiques, contextes et antécédents des symptômes permet au patient de les communiquer au clinicien qui pourrait avoir une explication différente de sa maladie. Cette étude de cas permet de montrer comment le Guide pour Formulation Culturelle du DSM-IV (The DSM-IV Outline for Cultural Formulation) permet aux cliniciens de solliciter un récit du patient en lien avec son expérience de la maladie. Notre étude examine l’utilisation par un patient laotien de « l’indignation sociale » (« Khuâm khum khang ») comme le modèle explicatif culturel de son problème malgré le diagnostic de trouble de stress post-traumatique qui lui fut attribué après une amputation traumatique. L’explication culturelle de son problème a permis au patient d’exprimer la signification personnelle et collective à sa colère et sa frustration, émotions qu’il avait réprimées. Cet idiome culturel lui a permis d’exprimer sa détresse et de réfléchir sur le système de soins de santé et, plus précisément, le contexte dans lequel les symptômes et leurs origines sont racontés et évalués. Cette représentation laotienne a aussi permis aux cliniciens de comprendre des expériences et les explications du client, autrement difficiles à situer dans un contexte biomédical et psychiatrique Euro-américain. Cette étude démontre comment il est possible d’améliorer les interactions entre cliniciens et patients et dès lors la qualité des soins par la compréhension de la perspective du patient et l’utilisation d’une approche culturelle. Mots clés: Culture, signification, idiome culturel, modèle explicatif, Guide pour Formulation culturelle du DSM-IV, indignation sociale, interaction entre patient et intervenant. ARTICLE 2 : RÉSUMÉ Impact de l’utilisation du Guide pour la formulation culturelle du DSM-IV sur la dynamique de conférences multidisciplinaires en santé mentale. La croissance du pluralisme culturel en Amérique du nord a obligé la communauté oeuvrant en santé mentale d’adopter une sensibilité culturelle accrue dans l’exercice de leur métier. Les professionnels en santé mentale doivent prendre conscience du contexte historique et social non seulement de leur clientèle mais également de leur propre profession. Les renseignements exigés pour les soins professionnels proviennent d’ évaluations cliniques. Il faut examiner ces informations dans un cadre culturellement sensible pour pouvoir formuler une évaluation des cas qui permet aux cliniciens de poser un diagnostic juste et précis, et ce, à travers les frontières culturelles du patient aussi bien que celles du professionnel en santé mentale. Cette situation a suscité le développement du Guide pour la formulation culturelle dans la 4ième édition du Manuel diagnostique et statistique des troubles mentaux américain (Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV) de l’Association psychiatrique américaine. Ce guide est un outil pour aider les cliniciens à obtenir des informations de nature culturelle auprès du client et de sa famille afin de guider la production des soins en santé mentale. L’étude vise l’analyse conversationnelle de la conférence multidisciplinaire comme contexte d’utilisation du Guide pour la formulation culturelle qui sert de cadre dans lequel les pratiques discursives des professionnels de la santé mentale évoluent. Utilisant la perspective théorique de l’interactionnisme symbolique, l’étude examine comment les diverses disciplines de la santé mentale interprètent et conceptualisent les éléments culturels et les implications de ce cadre pour la collaboration interdisciplinaire dans l’évaluation, l’élaboration de plans de traitement et des soins. Mots clé: Guide pour Formulation culturelle – Santé mentale – Psychiatrie transculturelle – Analyse conversationnelle – Interactionnisme symbolique

Using open source software for digital libraries A case study of CUSAT

The purpose of this paper is to describe the design and development of a digital library at Cochin University of Science and Technology (CUSAT), India, using DSpace open source software. The study covers the structure, contents and usage of CUSAT digital library. Design/methodology/approach – This paper examines the possibilities of applying open source in libraries. An evaluative approach is carried out to explore the features of the CUSAT digital library. The Google Analytics service is employed to measure the amount of use of digital library by users across the world. Findings – CUSAT has successfully applied DSpace open source software for building a digital library. The digital library has had visits from 78 countries, with the major share from India. The distribution of documents in the digital library is uneven. Past exam question papers share the major part of the collection. The number of research papers, articles and rare documents is less. Originality/value – The study is the first of its type that tries to understand digital library design and development using DSpace open source software in a university environment with a focus on the analysis of distribution of items and measuring the value by usage statistics employing the Google Analytics service. The digital library model can be useful for designing similar systems

Classification of textures seen from different distances and under varying illumination direction

Changes in the angle of illumination incident upon a 3D surface texture can significantly alter its appearance, implying variations in the image texture. These texture variations produce displacements of class members in the feature space, increasing the failure rates of texture classifiers. To avoid this problem, a model-based texture recognition system which classifies textures seen from different distances and under different illumination directions is presented in this paper. The system works on the basis of a surface model obtained by means of 4-source colour photometric stereo, used to generate 2D image textures under different illumination directions. The recognition system combines coocurrence matrices for feature extraction with a Nearest Neighbour classifier. Moreover, the recognition allows one to guess the approximate direction of the illumination used to capture the test image

Geochemical mapping of carbonate sediments in the Makgadikgadi basin, Botswana using moderate resolution remote sensing data

This paper maps the carbonate geochemistry of the Makgadikgadi Pans region of northern Botswana from moderate resolution (500 m pixels) remotely sensed data, to assess the impact of various geomorphological processes on surficial carbonate distribution. Previous palaeo-environmental studies have demonstrated that the pans have experienced several highstands during the Quaternary, forming calcretes around shoreline embayments. The pans are also a significant regional source of dust, and some workers have suggested that surficial carbonate distributions may be controlled, in part, by wind regime. Field studies of carbonate deposits in the region have also highlighted the importance of fluvial and groundwater processes in calcrete formation. However, due to the large area involved and problems of accessibility, the carbonate distribution across the entire Makgadikgadi basin remains poorly understood. The MODIS instrument permits mapping of carbonate distribution over large areas; comparison with estimates from Landsat Thematic Mapper data show reasonable agreement, and there is good agreement with estimates from laboratory analysis of field samples. The results suggest that palaeo-lake highstands, reconstructed here using the SRTM 3 arc-second digital elevation model, have left behind surficial carbonate deposits, which can be mapped by the MODIS instrument. Copyright (c) 2006 John Wiley & Sons, Ltd.

A geomatics-based approach for the derivation of the spatial distribution of sediment transport processes in periglacial mountain environments

Within this paper modern techniques such as satellite image analysis and tools provided by geographic information systems (GIS.) are exploited in order to extend and improve existing techniques for mapping the spatial distribution of sediment transport processes. The processes of interest comprise mass movements such as solifluction, slope wash, dirty avalanches and rock- and boulder falls. They differ considerably in nature and therefore different approaches for the derivation of their spatial extent are required. A major challenge is addressing the differences between the comparably coarse resolution of the available satellite data (Landsat TM/ETM+, 30 in x 30 m) and the actual scale of sediment transport in this environment. A three-stepped approach has been developed which is based on the concept of Geomorphic Process Units (GPUs): parameterization, process area delineation and combination. Parameters include land cover from satellite data and digital elevation model derivatives. Process areas are identified using a hierarchical classification scheme utilizing thresholds and definition of topology. The approach has been developed for the Karkevagge in Sweden and could be successfully transferred to the Rabotsbekken catchment at Okstindan, Norway using similar input data. Copyright (C) 2008 John Wiley & Sons, Ltd.