Hexagonal segmentations of space have long been known for their advantages vis à vis squared partitions in discretizing spatial variables, be it natural phenomena or human‐related features. However, readily available and easy‐to‐use tools to manipulate and interact with hexagonal rasters remain widely unavailable today. This article presents a first step to enable the use of hexagonal rasters in the GIS field. A format to encode cartographical hexagonal meshes as simple ASCII files is specified through a context‐free grammar. Named HexASCII, this file format provides a simple means of storing and sharing such rasters. A set of simple tools based on the HexASCII format is presented, allowing their creation and basic interaction with traditional GIS software. 相似文献
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... 相似文献
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.
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.... 相似文献
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. 相似文献
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. 相似文献
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. 相似文献