Spatio-temporal Conceptual Model Research Articles

High-permeability zones in folded and faulted silicified carbonate rocks – Implications for karstified carbonate reservoirs

Ascending hydrothermal fluid flow and subsequent hypogene karstification can control the formation of high-permeability zones in folded or faulted carbonate rocks. This study presents a multidisciplinary and multiscale approach to investigate the relationships between regional deformation and subseismic karst conduits along fracture corridors. We investigate the Cristal Cave Karst System, which is 6.7 km long and occurs in Mesoproterozoic carbonate-siliciclastic units affected by hydrothermal silicification in the São Francisco Craton, Brazil. Based on integrated techniques of ALOS PALSAR imagery, structural field surveys, stratigraphic and laboratory analyses in the caves and the surrounding surface outcrops, we highlight the following points: (1) the cave system occurs in a regional folded sector; (2) the internal architecture of the large regional folds is composed of subseismic folds; (3) fracture corridors occur along the subseismic fold hinges, forming high-permeability zones; and (4) the principal cave passages, which are oriented NNE-SSW, are concentrated along these fold hinges. We discuss the results in terms of a spatiotemporal conceptual model and unravel the deformation and karstification stages, which are characterized by the development of (i) precontractional and (ii) contractional structural networks followed by (iii) hydrothermal silicification and karstification processes. This cave system can be used as an analog for deformed, silicified, and karstified carbonate reservoirs, allowing for the in situ characterization of subseismic structural features. This study provides the key for first-order prediction and characterization of high-permeability zone internal structures, where both deformation and karstification processes occur.

Pyramidal Framework: Guidance for the Next Generation of GIS Spatial-Temporal Models

Over the last decade, innovative computer technologies and the multiplication of geospatial data acquisition solutions have transformed the geographic information systems (GIS) landscape and opened up new opportunities to close the gap between GIS and the dynamics of geographic phenomena. There is a demand to further develop spatio-temporal conceptual models to comprehensively represent the nature of the evolution of geographic objects. The latter involves a set of considerations like those related to managing changes and object identities, modeling possible causal relations, and integrating multiple interpretations. While conventional literature generally presents these concepts separately and rarely approaches them from a holistic perspective, they are in fact interrelated. Therefore, we believe that the semantics of modeling would be improved by considering these concepts jointly. In this work, we propose to represent these interrelationships in the form of a hierarchical pyramidal framework and to further explore this set of concepts. The objective of this framework is to provide a guideline to orient the design of future generations of GIS data models, enabling them to achieve a better representation of available spatio-temporal data. In addition, this framework aims at providing keys for a new interpretation and classification of spatio-temporal conceptual models. This work can be beneficial for researchers, students, and developers interested in advanced spatio-temporal modeling.

Mixing processes at an ice-covered river confluence

River confluences are characterized by a complex mixing zone with three-dimensional turbulent structures, which can be affected by the presence of an ice cover during the winter. The objective of this study is to characterize the flow structure in the mixing zone at a medium-size (~ 40 m) river confluence with and without an ice cover. Detailed velocity profiles were collected under the ice along the mixing plane with an Acoustic Doppler Velocimeter. For the ice-free conditions, drone imagery was used to characterize the mixing layer structures for various flow stages. Results indicate that during the ice-free conditions, very large Kelvin-Helmholtz (KH) coherent structures are visible due to turbidity differences, and occupy up to 50% of the width of the parent channel. During winter, the ice cover affects velocity profiles by moving the highest velocities towards the center of the profiles. Large turbulent structures are visible in both the streamwise and lateral velocity components. The strong correlation between these velocity components indicates that KH vortices are the dominating coherent structures in the mixing zone. A spatio-temporal conceptual model is presented to illustrate the main differences on the three-dimensional flow structure at the river confluence with and without the ice cover.

An Interoperable Spatio-Temporal Model for Archaeological Data Based on ISO Standard 19100

Archaeological data are characterized by both spatial and temporal dimensions that are often related to each other and are of particular interest during the interpretation process. For this reason, several attempts have been performed in recent years to develop a geographical information system (GIS) tailored for archaeological data. However, despite the increasing use of information technologies in the archaeological domain, the actual situation is that any agency or research group independently develops its own local database and management application that is isolated from the others. Conversely, the sharing of information and the cooperation between different archaeological agencies or research groups can be particularly useful to support the interpretation process by using data discovered in similar situations with respect to spatio-temporal or thematic aspects. In the geographical domain, the INSPIRE initiative of the European Union tries to support the development of a spatial data infrastructure (SDI) through which several organizations, such as public bodies or private companies, with overlapping goals can share data, resources, tools, and competencies in an effective way. The aim of this article is to lay the basis for the development of an archaeological SDI starting from the experience acquired during the collaboration among several Italian organizations. In particular, the article proposes a spatio-temporal conceptual model for archaeological data based on the ISO Standards of the 19100 family and promotes the use of the GeoUML methodology to put into practice such interoperability. The GeoUML methodology and tools have been enhanced to suit the archaeological domain and to automatically produce several useful documents, configuration files, and code base starting from the conceptual specification. The applicability of the spatio-temporal conceptual model and the usefulness of the produced tools have been tested in three different Italian contexts: Rome, Verona, and Isola della Scala.

Supporting User-Defined Granularities in a Spatiotemporal Conceptual Model

Granularities are integral to spatial and temporal data. A large number of applications require storage of facts along with their temporal and spatial context, which needs to be expressed in terms ...