Geostatistical Seismic Inversion with Self-Updating of Local Probability Distributions

Mathematical Geosciences - Three-dimensional subsurface elastic models inverted from seismic reflection data are the basis of the geo-modeling workflow. These models are often used to predict the...     

Investigation of potential debris flows above the Koroška Bela settlement,NW Slovenia,from hydro-technical and conceptual design perspectives

Debris flows are one of the natural disasters that can occur in the alpine environment, cause large economic damage, and endanger human lives. This study presents an overview of recent research done in relation to the debris flow hazard assessment and conceptual mitigation at the Koro?ka Bela area in Slovenia. This includes fieldwork, lab experiments, modelling, and a conceptual design of hydro-technical measures to reduce the risk. The results indicate that multiple debris flows occurred in the past in the area but a relatively long period of more than 100 years without an extreme event led to urbanization and development of the area. Magnitudes of the most extreme events as the worst-case scenarios were estimated to be in the range between 100,000 and 400,000 m³, using debris flow modelling and geological information from research trenches. Based on the landslide volumes, such events could also potentially occur in the future in extreme conditions. Additionally, torrential floods could mobilize more than 15,000 m³ of material located along the stream network that can be regarded as potentially unstable. The existing check dam system does not have the capacity to capture this material. Thus, a new check dam and three flexible net barriers could help to reduce the risk due to torrential outbursts or debris flows.

     

Style Transfer applied to CT image downscaling: a study case from Brazilian Coquinas

Computational Geosciences - The identification of micropore systems in carbonate rocks is an important task of image processing because of the high impact these systems cause on fluid flow....     

Transpiration in Quercus suber trees under shallow water table conditions: the role of soil and groundwater

Water is one of the major environmental factors limiting plant growth and survival in the Mediterranean region. Quercus suber L. woodlands occupy vast areas in the Iberian Peninsula, frequently under shallow water table conditions. The relative magnitude of soil and groundwater uptake to supply transpiration is not easy to evaluate under these circumstances. We recently developed a conceptual framework for the functioning of the root system in Q. suber that simulates well tree transpiration, based on two types of root behaviour: shallow connected and deep connected. Although this significantly improved knowledge on the functional traits of Mediterranean Q. suber, the approach has the limitation of requiring root sap flow data, which are seldom available. In this work, we present alternative methodologies to assess if trees are connected to groundwater and to estimate the soil and groundwater contributions to tree transpiration. We provide evidence on the tree unrestricted access to groundwater solely based on meteorological, stem sap flow and leaf water potential data. Using a soil mass balance approach, we estimated the yearly soil and groundwater contributions to tree transpiration: 69.7% and 30.3%, respectively. Groundwater uptake became dominant in the dry summer: 73.2% of tree transpiration. Results reproduce extremely well those derived from root modelling. Because of its simplicity both in formulation and data requirements, our approach is potentially liable to be adapted to other groundwater‐dependent Mediterranean oak sites, where interactions between land use and water resources may be relevant. Copyright © 2013 John Wiley & Sons, Ltd.     

Intra‐messinian gypsum palaeokarst in the Northern Apennines and its palaeogeographic implications

A short intra‐Messinian continental period has been recognised in some North Italian gypsum areas, mostly under the form of palaeokarst deposits. This emersion appears to have occurred only locally, and is explained as caused by the intra‐Messinian tectonic phase and a major sea level lowering. Evidences of this palaeokarst are mostly small, although at some places the palaeontological content of its fillings is of great importance. The discovery near Zola Predosa (Bologna) of a new intra‐Messinian extensive karst system and of its infilling sheds new light on the importance of this karst episode.     

Polycyclic aromatic hydrocarbons in recent sediments from a subtropical estuary in Brazil

The scope of this work was to evaluate the levels of polycyclic aromatic hydrocarbons (PAHs) and their possible sources in two shallow sediment cores from an estuarine area located in the south region of Brazil, the Guaratuba Bay. The estuary is encompassed by an Environmental Protection Area (EPA) of 1306 km², which is still considered to be pristine, despite recent urban growth. To assess levels of 14 selected PAHs in the sediments, among those listed as “priority pollutants” by the US Environmental Protection Agency, the cores were divided in several sections, followed by extraction, clean-up, fractionation and subsequent analysis using HPLC coupled to a fluorescence detector. Among the PAHs detected, phenanthrene and fluoranthene showed the highest concentrations. PAHs with more than four rings were usually present in low concentrations or were undetectable. To assist in the identification of possible sources, the ratios An/(An + Phe) and Flt/(Flt + Py) (anthracene to anthracene plus phenanthrene and fluoranthene to fluoranthene plus pyrene) and a PCA model were also used. Total concentrations of PAHs ranged between 1.5 and 3130 ng/g (mean 495) dry weight for the core collected in the inner part of the estuary, and between 78.5 and 3270 ng/g (mean 899) dry weight for the other core, collected in the outer part. Compared to values found in other studies in coastal zones along South American eastern margin, this area can be considered to range from low polluted to moderately polluted. From the data, it was also possible to conclude that there is predominance of petroleum sources, and essentially close to the more urbanised areas. Combustion sources have only minor contribution and are episodic, when compared to the latter.     

Non‐synchronous deposition of North Atlantic Ash Zone II in Greenland ice cores,and North Atlantic and Norwegian Sea sediments: an example of complex glacial‐stage tephra transport

Tephra provides regional chronostratigraphical marker horizons that can link different climate archives with highly needed accuracy and precision. The results presented in this work exemplify, however, that the intermittent storage of tephra in ice sheets and during its subsequent iceberg transport, especially during glacial stages, constitutes a potential source of serious error for the application of tephrochronology to Nordic Seas and North Atlantic sediment archives. The peak shard concentration of the rhyolitic component of the North Atlantic Ash Zone II (NAAZ‐II) tephra complex, often used to correlate marine and ice core records in Marine Isotope Stage (MIS) 3, is shown to lag the eruption event by ca. 100–400 years in some North Atlantic and Norwegian Sea cores. While still allowing for a correlation of archives on millennial timescales, this time delay in deposition is a major obstacle when addressing the lead–lag relationship on short timescales (years to centuries). A precise and accurate determination of lead–lag relationships between archives recording different parts of the climate system is crucial in order to test hypotheses about the processes leading to abrupt climate change and to evaluate results from climate models. Copyright © 2011 John Wiley & Sons, Ltd.     

Sensitivity Analysis of Time Dependent Settlements in Hydraulic Fills

This paper reports some numerical investigation carried out on hydraulic fills. A methodology based on the numerical solution of the governing equation via the finite volume method is introduced and tested, and proven to be very efficient. Typical dimensional performance curves are obtained and the influence of governing parameters is discussed. A sensitivity analysis is carried out in order to characterize the influence of the numerous parameters used to simulate the time dependent settlement in hydraulic fills on the outputs of the model.     

Formulation of a tropical town energy budget (t-TEB) scheme

This work describes the tropical town energy budget (t-TEB) scheme addressed to simulate the diurnal occurrence of the urban heat island (UHI) as observed in the Metropolitan Area of Rio de Janeiro (MARJ; ?22° S; ?44° W) in Brazil. Reasoning about the tropical urban climate have guided the scheme implementation, starting from the original equations from Masson (Bound-Lay Meteorol 94:357–397, 2000). The modifications include (a) local scaling approaches for obtaining flux–gradient relationships in the roughness sub-layer, (b) the Monin-Obukhov similarity framework in the inertial sub-layer, (c) increasing aerodynamic conductance toward more unstable conditions, and (d) a modified urban subsurface drainage system to transfer the intercepted rainwater by roofs to the roads. Simulations along 2007 for the MARJ are obtained and compared with the climatology. The t-TEB simulation is consistent with the observations, suggesting that the timing and dynamics of the UHI in tropical cities could vary significantly from the familiar patterns observed in mid-latitude cities—with the peak heat island intensity occurring in the morning than at night. The simulations are suggesting that the thermal phase shift of this tropical diurnal UHI is a response of the surface energy budget to the large amount of solar radiation, intense evapotranspiration, and thermal response of the vegetated surfaces over a very humid soil layer.     

Application of Fuzzy Sets to the Determination of Sunspot Areas

The computation of sunspot areas is important for many applications in solar physics. Some uncertainty is, however, inherent to this determination, since there is uncertainty in defining the limits of sunspots, as well as their umbrae and penumbrae, particularly in high-resolution images where large variations in intensity are observed, mainly in the penumbrae and photosphere regions. In this paper a methodology based on the classical histogram method is presented that enables the generation of fuzzy sets that correspond to the umbrae and penumbrae of sunspots, as well as to the complete sunspots, which enable the representation of the uncertainty in their locations. The areas of the sunspots and of their umbrae and penumbrae are then obtained by computing the areas of the fuzzy sets used to represent them. Two operators are used: the Rosenfeld Area operator, which generates a real number for the area, and the Fuzzy Area operator, which generates a fuzzy number, providing more information about the uncertainty of the area. A comparison of the obtained results with the area values given by the classical cumulative histogram method is made and the differences analyzed.