Identifying the flow pattern and natural recharge at a strategic groundwater resource in the Dornogobi Province,Mongolia     

Adam Ricka  Tomas Kuchovsky  Batmunkh Damdindorj  Vilem Fürych  Antonin Kopriva  Khukhuu Puntsag 《水文科学杂志》2018,63(9):1408-1423

The strategic project of economic development in the Dornogobi Province in Mongolia is dependent on water supply. Thus a comprehensive hydrogeological characterization was focused on the Upper Cretaceous multi-aquifer system north of Sainshand city. A conceptual model was developed to discover the groundwater flow pattern essential to correct the setting of the numerical model of groundwater flow created using MODFLOW to assess the natural recharge of the aquifer. The conceptualization was based on geological and hydrogeological characterization. However, the evaluation of hydrochemistry proved to be the key factor revealing the principal feature of the groundwater flow pattern, which is the presence of preferential flow zones. These zones allow for intensive transfer of relatively fresh Na(Mg,Ca)?HCO₃-dominated groundwater into discharge areas, where it leaks into the Quaternary aquifer. The numerical model suggested an enormous natural recharge of 22 100 m³/d, originating in 64% of the preferential flow zones.  相似文献   

Modelling multiseasonal preferential transport of dissolved organic carbon in a shallow forest soil: Equilibrium versus kinetic sorption     

Jaromir Dusek  Michal Dohnal  Tomas Vogel  Anne Marx  Johannes A.C. Barth 《水文研究》2019,33(22):2898-2917

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The Potential of Virtual Reality Technology for Analysis of Remotely Sensed Data: A Lidar Case Study     

Timothy Warner  M. Duane Nellis  Tomas Brandtberg  James B. McGraw  Joseph V. Gardner 《国际地球制图》2013,28(1):25-32

Abstract

Although the GIS community has been quick to exploit the advantages of virtual reality (VR) for display and analysis of spatial data, VR does not appear to have been exploited widely for remote sensing data analysis. A case study of high resolution lidar data acquired over a deciduous forest near Morgantown, WV was used to investigate the potential and limitations of current VR software for remote sensing analysis. The functionality within a standard remote sensing software package was found to provide a good overview of interpolated, smoothed lidar data, but was less useful for gridded data that had not been interpolated. With gridded data, it was possible to drape orthophotographs or other images over the lidar data, providing a useful method for investigating relationships between lidar and other data. Alternatively, using a commercial VR package, it was possible to view the original lidar point data, and thus visualize the multiple returns from within the canopy of each tree. The point data were preferable for identification of surfaces within the data cloud, especially the ground surface. For a fully integrated remote sensing VR package, functionality will be needed to link point and interpolated coverages, and also to enhance the interactive selection of data for further statistical analysis.  相似文献   

Impact of horizontal eddy diffusivity on Lagrangian statistics for coastal pollution from a major marine fairway     

Bert Viikmäe  Tomas Torsvik  Tarmo Soomere 《Ocean Dynamics》2013,63(5):589-597

Lagrangian trajectory methods are often applied as deterministic transport models, where transport is due strictly to advection without taking into account stochastic elements of particle dispersion, which raises questions about validity of the model results. The present work investigates the impact of horizontal eddy diffusivity for a case study of coastal pollution in the Gulf of Finland, where the pollutants are assumed to originate from a major fairway and are transported to the coast by surface currents. Lagrangian trajectories are calculated using the TRACMASS model from velocity fields calculated by the Rossby Centre circulation model for 1982 to 2001. Three cases are investigated: (1) trajectory calculation without eddy diffusivity, (2) stochastic modelling of eddy diffusivity with a constant diffusion coefficient and (3) stochastic modelling of eddy diffusivity with a time- and space-variable diffusion coefficient. It is found that the eddy diffusivity effect increases the spreading rate of initially closely packed trajectories and the number of trajectories that eventually reach the coast. The pattern of most frequently hit coastal sections, the probability of hit to each such section and the time the pollution spends offshore are virtually invariant with respect to inclusion of eddy diffusivity.  相似文献   

A travel time-based variable grid approach for an activity-based cellular automata model     

Tomas Crols  Roger White  Inge Uljee  Guy Engelen  Lien Poelmans  Frank Canters 《International journal of geographical information science》2013,27(10):1757-1781

Urban growth and population growth are used in numerous models to determine their potential impacts on both the natural and the socio-economic systems. Cellular automata (CA) land-use models became popular for urban growth modelling since they predict spatial interactions between different land uses in an explicit and straightforward manner. A common deficiency of land-use models is that they only deal with abstract categories, while in reality, several activities are often hosted at one location (e.g. population, employment, agricultural yield, nature…). Recently, a multiple activity-based variable grid CA model was proposed to represent several urban activities (population and economic activities) within single model cells. The distance-decay influence rules of the model included both short- and long-distance interactions, but all distances between cells were simply Euclidean distances. The geometry of the real transportation system, as well as its interrelations with the evolving activities, were therefore not taken into account. To improve this particular model, we make the influence rules functions of time travelled on the transportation system. Specifically, the new algorithm computes and stores all travel times needed for the variable grid CA. This approach provides fast run times, and it has a higher resolution and more easily modified parameters than the alternative approach of coupling the activity-based CA model to an external transportation model. This paper presents results from one Euclidean scenario and four different transport network scenarios to show the effects on land-use and activity change in an application to Belgium. The approach can add value to urban scenario analysis and the development of transport- and activity-related spatial indicators, and constitutes a general improvement of the activity-based CA model.  相似文献   

Observing the critical zone on a critical budget: The Peri Lake experimental catchment     

Pedro Luiz Borges Chaffe  Camyla Innocente dos Santos  Alondra Beatriz Alvarez Perez  João Henrique Macedo Sá  Tomas Carlotto  Leonardo Hoinaski 《水文研究》2021,35(3):e14087

The Peri Lake Experimental Catchment, in Southern Brazil, is a small coastal lake (5 km², 7 m depth) with a total catchment area of 20 km². The catchment is mainly covered by subtropical Atlantic Forest. Peri Lake is a recreational destination, an important ecosystem for biodiversity preservation, and a major water supply source. Even though there is a clear social and economic relevance, the information on this ecosystem is scarce, especially regarding the dynamics of water balance and water quality. We built this observatory using a low-cost, low-technology monitoring system to estimate the major components of the water budget on what we called a critical budget. We monitor meteorology, rainfall interception in two plots, overland flow and groundwater connectivity in a representative hillslope; and streamflow and velocity are measured in several small headwater rivers mostly starting during 2015. Geographic information on topography, land cover, geology, soil characteristics and the location of all the equipment installed in the field are also provided. The data set can be used to understand rainfall interception in Atlantic forests, catchment connectivity and streamflow permanence in coastal areas, spatial patterns of baseflow, and the modelling of complex processes in the critical zone involving the interaction between surface and groundwater, that are important in coastal lake ecosystems. Besides being used for research and education, we hope this observatory built on a shoestring budget will encourage fieldwork particularly in underrepresented and underfunded regions of the world.  相似文献   

Experimental study of the leak-tightness of water-containing silicate-melt inclusions under the pressure of D₂O at 650 °C and 3 kbar     

S.Z. Smirnov  V.G. Tomas  E.N. Sokolova  I.N. Kupriyanov 《Russian Geology and Geophysics》2011,52(5):537-547

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Feedback Mechanisms Between Cyanobacterial Blooms,Transient Hypoxia,and Benthic Phosphorus Regeneration in Shallow Coastal Environments     

Mindaugas Zilius  Marco Bartoli  Mariano Bresciani  Marija Katarzyte  Tomas Ruginis  Jolita Petkuviene  Irma Lubiene  Claudia Giardino  Paul A. Bukaveckas  Rutger de Wit  Arturas Razinkovas-Baziukas 《Estuaries and Coasts》2014,37(3):680-694

We investigated the dissolved oxygen metabolism of the Curonian Lagoon (Baltic Sea) to assess the relative contributions of pelagic and benthic processes to the development of transient hypoxic conditions in shallow water habitats. Metabolism measurements along with the remote sensing-derived estimates of spatial variability in chlorophyll a were used to evaluate the risk of hypoxia at the whole lagoon level. Our data demonstrate that cyanobacterial blooms strongly inhibit light penetration, resulting in net heterotrophic conditions in which pelagic oxygen demand exceeds benthic oxygen demand by an order of magnitude. The combination of bloom conditions and reduced vertical mixing during calm periods resulted in oxygen depletion of bottom waters and greater sediment nutrient release. The peak of reactive P regeneration (nearly 30 μmol m^?2 h^?1) coincided with oxygen depletion in the water column, and resulted in a marked drop of the inorganic N:P ratio (from >40 to <5, as molar). Our results suggest a strong link between cyanobacterial blooms, pelagic respiration, hypoxia, and P regeneration, which acts as a feedback in sustaining algal blooms through internal nutrient cycling. Meteorological data and satellite-derived maps of chlorophyll a were used to show that nearly 70 % of the lagoon surface (approximately 1,000 km²) is prone to transient hypoxia development when blooms coincide with low wind speed conditions.  相似文献   

3s²3p–3s3p² transitions in S iv     

Alan Hibbert  Tomas Brage  Janine Fleming 《Monthly notices of the Royal Astronomical Society》2002,333(4):885-893

We use both the civ3 and mchf codes to calculate oscillator strengths of allowed and intercombination lines in the  3s²3p–3s3p²  multiplets. Valence, core–valence and some core–core correlation effects are included. The two approaches give results in excellent agreement. Core effects are particularly important for the intercombination lines, though relatively minor for allowed transitions.
We obtain a branching ratio of 1.42 with an estimated accuracy of 0.02 for the     transitions, compared with an experimental value of  1.12±0.1  . The A -values of the     intercombination lines are substantially different from those of previous calculations.  相似文献   

Estimation of baseflow residence times in watersheds from the runoff hydrograph recession: method and application in the Neversink watershed,Catskill Mountains,New York     

Tomas Vitvar  Douglas A. Burns  Gregory B. Lawrence  Jeffrey J. McDonnell  David M. Wolock 《水文研究》2002,16(9):1871-1877

A method for estimation of mean baseflow residence time in watersheds from hydrograph runoff recession characteristics was developed. Runoff recession characteristics were computed for the period 1993–96 in the 2 km² Winnisook watershed, Catskill Mountains, southeastern New York, and were used to derive mean values of subsurface hydraulic conductivity and the storage coefficient. These values were then used to estimate the mean baseflow residence time from an expression of the soil contact time, based on watershed soil and topographic characteristics. For comparison, mean baseflow residence times were calculated for the same period of time through the traditional convolution integral approach, which relates rainfall δ¹⁸O to δ¹⁸O values in streamflow. Our computed mean baseflow residence time was 9 months by both methods. These results indicate that baseflow residence time can be calculated accurately using recession analysis, and the method is less expensive than using environmental and/or artificial tracers. Published in 2002 by John Wiley & Sons, Ltd.  相似文献