A parallel mesh-free contaminant transport model based on the Analytic Element and Streamline Methods     

Karl W. Bandilla  Alan J. RabideauIgor Janković 《Advances in water resources》2009

This paper introduces a new method for simulating large-scale subsurface contaminant transport that combines an Analytic Element Method (AEM) groundwater flow solution with a split-operator Streamline Method for modeling reactive transport. The key feature of the method is the manner in which the vertically integrated AEM flow solution is used to construct three-dimensional particle tracks that define the geometry of the Streamline Method. The inherently parallel nature of the algorithm supports the development of reactive transport models for spatial domains much larger than current grid-based methods. The applicability of the new approach is verified for cases with negligible transverse dispersion through comparisons to analytic solutions and existing numerical solutions, and parallel performance is demonstrated through a realistic test problem based on the regional-scale transport of agricultural contaminants from spatially distributed sources.  相似文献   

Azimuthal anisotropy of the Pg-wave velocity in hypocentral volumes of NW Croatia     

Marijan Herak  Davorka Herak  Josip Stipčević 《Acta Geophysica》2009,57(3):600-615

Based on a large set of arrival times of the Pg phase reported by local and regional stations, we estimate azimuthal anisotropy of the Pg-wave velocity in focal volumes of the upper crust in NW Croatia. The method is based on analyses of the azimuthal dependence of ratios of cumulative differences of arrival times and travel paths between foci of earthquake pairs, computed for rays propagating within narrow azimuthal windows. The results clearly indicate the presence of anisotropy of 3.3% with the direction of fast velocity (approximately NNE-SSW) coinciding with the direction of the maximum tectonic pressure as revealed by 23 available focal mechanisms and previous geological investigations. Although a large part of observed anisotropy can be explained assuming that focal volumes are pervaded by a system of vertical extensive-dilatancy anisotropy (EDA) cracks aligned under the influence of local tectonic stress field, there is indication that — to a smaller extent — some role was also played by alignment of structural features in the region.  相似文献   

Changes in Components of the Water Balance in the Croatian Lowlands     

K. Zaninović  M. Gajić-Čapka 《Theoretical and Applied Climatology》2000,65(1-2):111-117

Summary ?This paper deals with variations and trends in some components of the water balance: the soil water content; evaporation loss from the soil (from the surface and underlying layers); transpiration; ground water recharge and runoff. These components are calculated by means of the Palmer procedure. This analysis is based on data from Osijek, Croatia from this century (1900–1995). Besides the meteorological input parameters necessary for the water balance calculations, i.e. precipitation, temperature and relative humidity, the pedological characteristics of this area have also been taken into account. Fluctuations have been considered by means of the 11-year binomial filtered series and linear trends were tested by means of the Mann-Kendall rank test. For a closer look on the trends of water balance components, a progressive analysis of the time series was performed, too. The results show a significant increase in potential evapotranspiration and evapotranspiration and decrease in runoff and soil water content has occurred during the century. Received February 22, 1999/Revised August 3, 1999  相似文献   

NEAT approach for testing and validation of geospatial network agent-based model processes: case study of influenza spread     

Taylor Anderson  Suzana Dragićević 《International journal of geographical information science》2020,34(9):1792-1821

ABSTRACT

Agent-based models (ABM) are used to represent a variety of complex systems by simulating the local interactions between system components from which observable spatial patterns at the system-level emerge. Thus, the degree to which these interactions are represented correctly must be evaluated. Networks can be used to discretely represent and quantify interactions between system components and the emergent system structure. Therefore, the main objective of this study is to develop and implement a novel validation approach called the NEtworks for ABM Testing (NEAT) that integrates geographic information science, ABM approaches, and spatial network representations to simulate complex systems as measurable and dynamic spatial networks. The simulated spatial network structures are measured using graph theory and compared with empirical regularities of observed real networks. The approach is implemented to validate a theoretical ABM representing the spread of influenza in the City of Vancouver, Canada. Results demonstrate that the NEAT approach can validate whether the internal model processes are represented realistically, thus better enabling the use of ABMs in decision-making processes.  相似文献   

Ombla Spring,Croatia     

P. Milanović 《Environmental Geology》1996,27(2):105-107

Ombla Spring is located on the Adriatic coast near the town of Dubrovnik. The spring discharges at sea level. To eliminate the influence of the tide, a small dam was constructed 50 m downstream of the spring outlet. The spring water overflows the dam crest at an elevation of 2.40 m. Since 1897 the springwater has been used for the water supply for Dubrovnik.  相似文献   

Numerical study of the cloud seeding effects     

Prof. Dr. M. Ćurić M.Sc.  M.Sc. D. Janc 《Meteorology and Atmospheric Physics》1990,42(2):145-164

The microphysical model with the bulk water parameterization is applied to simulated both contact and deposition nucleation as well as the imersion freezing for unseeded cases and the cases immediately after seeding performed for the cold continental Cb clouds with small cloud droplets. The injection of agent AgI is performed in temperature region between –8°C and –12°C. The four groups of sensitivity experiments are executed.

a.	The Brownian coagulation of rain drops is the most important contact nucleation mechanism for seeded cases with great amount of rain drops. When cloud droplets mainly contribute to the liquid water content for seeded cases, the Brownian coagulation of cloud droplets is the primary nucleation mechanism while the inertial impact is the less effective contact nucleation mechanism;
b.	the mutual interdependence of contact and deposition nucleation mechanisms shows that the contact nucleation is more effective for graupel production than the deposition one for the temperature region considered in this model;
c.	the imersion freezing is the most important mechanism for all cases with significant amount of rain drops. It is more effective than the contact nucleation mechanism in unseeded cases with insufficient number of rain drops;
d.	the nucleation mechanisms are more sensitive to temperature changes than to pressure changes.

With 14 Figures  相似文献   

Influence of construction on hydrogeological and environmental conditions in the karst region,eastern Herzegovina,Yugoslavia     

Petar Milanović 《Environmental Geology》1990,15(1):5-11

The region of eastern Herzegovina and Dubrovnik coastal belt is one of the hydrogeologically and hydrologically most interesting regions of Yugoslavia karst. The main water course in the region is the Trebinjica river, the largest sinking river in Europe. All the poljes in the catchment area are temporary flooded, hydrologically separated, and closed karst entities. Enormous quantities of available water are not evenly disturbed neither in the time nor in the space. The Trebinjica Hydrosystem project uses the basic concept of total water regime organization and its multipurpose utilization. With the construction of seven dams, six artificial reservoirs, six tunnels (with total length, 57 km), and four canals (with total length 74 km) the natural regime of surface and underground waters has been completely changed.As a consequence of water regime disturbance, a lot of changes have been observed in the catchment area: changes in the karst aquifers; local changes of climate conditions; eolic erosion effect; influence on the karst underground and littoral belt; influence on the springs yield; influence on adjacent catchment area; pollution of karst aquifers and influence of storage reservoirs on seismicity—induced seismicity. This article presents influences observed after the first stage of hydrosystem construction.  相似文献   

Are prominent mountains frequently mentioned in text? Exploring the spatial expressiveness of text frequency     

Curdin Derungs  Tanja Samardžić 《International journal of geographical information science》2018,32(5):856-873

Data-driven GIScience shows a growing interest in making spatial information from large text data. In this paper, we quantify and thus evaluate the relation between text frequency and properties of the outer-text, geographic setting by comparing text frequencies of mountain names to the respective geomorphometric characteristics. We focus on some 2000 unique mountain names that appear some 50,000 times in a large compilation of texts on Swiss alpine history. The results on the full data set suggest only a weak relation: only 5–10% of the variation in the text frequency being explained by the respective geomorphometric characteristics. However, an analysis of multiple scales allows us to identify a Simpson’s Paradox. What appears to be ‘noise’ in the analysis of all mountains in the whole of Switzerland shows significant local signals. Small spatial extents, found all over Switzerland, can show considerably strong correlations between text frequency and spatial prominence, with up to 90% of the total variation explained. We argue that our findings have practical implications for data-driven GIScience. Retrieving meaningful spatial information from text might only be possible if the spatial scale of analysis reflects the spatial scale described in the input text documents.  相似文献   

Quality Assessment of an Automatic Sounding Selection Process for Navigational Charts     

Dejan Lovrinčević 《The Cartographic journal》2017,54(2):139-146

A good seabed representation is one of the important characteristics of any navigational chart. Along with depth contours and coloured depth areas, soundings are used for this task. All the soundings on a navigational chart are selected for a reason. Soundings contribute to the navigational chart safety aspect by alerting to all the threats and dangers. They also show all the attributes of a seabed relief without overcrowding it, thus maintaining the overall chart quality. Soundings are selected from a hydrographic survey and since it consists of a vast number of data, the process of sounding selection is a challenging and demanding task. It requires experience and knowledge from the nautical cartographer and is mostly done manually. Some types of software nowadays provide an automatic selection feature. This paper analyses a process of automatic sounding selection in the dKart Editor software. On the Croatian side of the Adriatic Sea, ?ibenski Kanal (?ibenik channel) and Kanal Sv. Ante (St. Ante’s channel) are used as the study area. A hydrographic survey of the area represents the input data. The official navigational chart of the surveyed area is used as the basis for determining three different sets of parameters for the selection process. After the selection, obtained results are assessed based on geometrical accuracy and on the conservation level of navigational safety. For geometrical accuracy, the best results were produced by the third set that was divided in two subsets for each channel. It was determined that the nature of the seabed relief had an impact on the selection process. The same set had the best result for navigational safety assessment but it was concluded that all the sets undermined the aspect. Because of these crucial shortcomings noticed in all the tested sets of parameters, the feature is considered inadequate for serious usage as a completely automatic tool for the process of sounding selection on navigational charts.  相似文献   

Magmatism and metallogeny of the Ridanj-Krepoljin belt (eastern Serbia) and their correlation with northern and eastern analogues     

S. Karamata  V. Knežević  Z. Pécskay  M. Djordjević 《Mineralium Deposita》1997,32(5):452-458

In the southwestern Carpathians of SW Romania and E Serbia calc-alkaline Upper Cretaceous-Paleogene subduction related magmatic rocks occur in two main zones. The Ridanj-Krepoljin belt (E Serbia) represents the southern part of the western zone. In this belt Early Maastrichtian dacites and subordinate andesites occur, but there are indications of an unexposed granodioritic (?) magmatism about 60 Ma old. Pb-Zn-Ag and only subordinate Cu mineralization is associated with this igneous activity. The Timok magmatic complex (E Serbia) composed of Upper Cretaceous (-Paleocene?) andesites and analogue intrusives represents the eastern zone south of the Danube. Associated with this magmatism are Cu (+Au) and very subordinate Zn (±Pb) mineralization. To the north (SW Romania) in both zones mainly intrusive bodies (diorites, quartz diorites, granodiorites, monzonites) of Campanian-Paleocene age are exposed. Porphyry copper (+Mo) and in north Pb-Zn (±Cu) mineralization are related to those intrusives. The petrological and geochemical features of all these calc-alkaline rocks are very similar. It appears, however, that the associated polymetallic and the copper mineralization are both spatially and vertically separated.  相似文献