Evaluation of River Water Quality Simulations at a Daily Time Step – Experience with SWAT in the Axe Catchment,UK     

Matjaž Glavan  Sue White  Ian P. Holman 《洁净——土壤、空气、水》2011,39(1):43-54

The Water Framework Directive (WFD) was established for the protection of surface waters (rivers, lakes, transitional and coastal waters) and ground waters in the European Union. The main environmental objective is to achieve and maintain a good status for all waters by the target date of 2015. Models which are able to address the majority of environmental objectives are proposed within the WFD to inform the management changes required to meet current water policy goals. The use of the Soil and Water Assessment Tool (SWAT) catchment model is widespread throughout the world, especially to support river basin management as required by the WFD. This paper provides a critical evaluation of the use of the model by placing model performance in the Axe catchment, UK, in the context of international performance of the model. Within the constraints of the available data, SWAT represents hydrology, sediment and ortho‐phosphorus concentration well for this heterogeneous catchment, but the representation of daily nitrogen concentration dynamics is poor. Temporal aggregation of model outputs from daily to monthly improved the performance metrics for all the river outputs, including nitrate. Wider review of SWAT studies showed widespread reporting of monthly performance metrics within the SWAT studies, despite the model operating at a daily time step. Poor performance for nitrate identified in this current study may be a significant factor in the choice to not report daily results. This demonstrates the importance of ascertaining the reasons for the use of temporal aggregation in modelling studies.  相似文献   

The impact of morphostructural development on the extension of the North European Ice at the main European watershed in the Moravian Gate (Czech Republic)     

Vít Voženílek 《GeoJournal》1994,32(3):241-245

The territory of the Czech Republic has been investigated by geographers for many decades. The Moravian Gate situated in the eastern part of the Czech Republic, became a place of high human concentration due to its geographical location. Geomorphological research in the Czech republic has reached an impressive level in the field of both the morphostructure of the whole territory and the extent of glaciation. The article treats the relationship between the morphostructure and the extent of glaciation in a geographically complicated region. Both of these have been investigated separately. The synthesis of all results brings new knowledge and suggestions for future research in the region close to the main European watershed. The paper is completed on the basis of the author's research including the complex geomorphological analysis, especially morphostructural and morfosculptural analysis, the investigation of the features and genesis of georelief, the digital elevation model of studied area, the detailed geomorphological mapping in 1:10.000 scale and the compilation of denudation chronology.  相似文献   

Changing local finances in the Czech Republic — half way over?     

Jiří Blažek 《GeoJournal》1994,32(3):261-267

Far-reaching changes launched in 1989, aimed mainly at establishing a democratic society and market economy have clearly brought many positive results. However, there is also a negative side to these progressive changes both in economic and social spheres. There are many difficult tasks ahead such as the reestablishment of a democratic and economically effective local government which will be able to fulfil contemporary needs and requirements. The aim of this report is not to describe all the changes occurring in local government or to review different opinions about what should be done, but rather to concentrate on one of the most important issues facing this body of government, that of financial reform. Special attention will be given to the economic performance of municipalities with regard to their population size. It will be argued that data from local budgets can reveal important features about the performance of local and regional economies which cannot be obtained in any other way.  相似文献   

Some evaluations of hail suppression system efficiency in Slovenia,Yugoslavia     

J. Rakovec  B. Gregorčič  A. Kranjc  T. Mekinda  L. Kajfež-Bogataj 《Theoretical and Applied Climatology》1990,41(3):157-171

Summary The efficiency of hail suppression is studied for the operative, non-randomized system established in 1971 on a territory of a 256.000 ha and enlarged in the eighties to almost 970.000 ha (Fig. 1). The system was built with thea priori assumption that it is successful and so no special effort was made to collect the data necessary for the testing of its efficiency. However, some data are still at disposal for this purpose: the daily and five minutes interval precipitation data, the radar cloud variables data used as seeding criteria, the data on days with thunderstorms and with hail, and (not abundant) set of data on the damages in agriculture as collected by an insurance company. A statistical evaluation of these data on the significance of the eventual differences between target and control area and/or before and during the project period do not confirm the hypothesis that the system is successful at some acceptable significance level (90 or 95%). The conclusion that the efficiency of the hail suppression system could not be proved holds for the system as a whole: for the theoretical part and the operational one, with all the accompanying advantages and malfunctions.With 7 Figures  相似文献   

Principal Component analysis of a local temperature field within the global circulation     

K. Pandžić  M. Kisegi 《Theoretical and Applied Climatology》1990,41(4):177-200

  相似文献   

On the problem of quasi-electrostatic whistler mode waves: A possible interpretation of discrete plasmaspheric emissions     

Jaroslava Bošková  František Jiříček  Pavel Tříska  B. V. Lundin  D. R. Shklyar  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1988,32(2):199-212

Summary In a number of VLF experiments with low-orbiting Intercosmos satellites, high-intensity, discrete VLF emissions at frequencies above the local LHR were observed predominantly between L=2.3 and 4.0. The frequency of their intensity maximum varies continuously with geomagnetic latitude, and approximately parallels the value of a quarter of the equatorial electron gyrofrequency. An attempt is made to interprete these emissions in terms of quasi-electrostatic whistler-mode waves, generated in the near-equatorial region and propagating downward in the quasi-resonance mode. The generating mechanism is supposed to be the kinetic instability connected with the loss-cone and temperature anisotropy of the distribution function of energetic electrons. Some features of the discrete plasmaspheric emissions are discussed on the basis of theoretical considerations.

---

¶rt; num a umu nmua m a¶rt;au umu ¶rt;um -uu a amma, a amm , num ¶rt; L=2,3 u L=4. amma aua umumu mu uu um uuaum um u nuuum aa mmu amuauamm m. ¶rt;numa nnma umnmuam mu uu mua aummamuu um , ¶rt;a nuamua amu u anmau u au-a u. ¶rt;naam, m mu uu ¶rt;am mam umu mumu an¶rt;u u m, aumnu mnam u nm u uu an¶rt;u. n mmu aau ¶rt;am m mu ¶rt;umm na uu.

  相似文献   

Experimental and numerical study of hygro-thermo-mechanical properties of “Schilfsandstein” from Baden-Württemberg   总被引：1，自引：0，他引：1  

J. Ožbolt  G. Grassegger  P. Van der Veken  G. Periškić  H.-W. Reinhardt 《Environmental Geology》2008,56(3-4):535-546

In the present paper the results of experimental and numerical investigations of hygro-thermo-mechanical properties of “Schilfsandstein” from Baden-Württemberg are presented and discussed. The aim of the study was to investigate the influence of extreme environmental conditions causing severe damage that can often be observed on various monuments during restoration and reconstruction process. In the experimental investigations the stone specimen was exposed to extreme hygro-thermal conditions, which caused significant damage (cracking). During the experiment the ultrasonic and acoustic emission analyses were performed. Subsequently, a 3D finite element analysis was carried out using a coupled hygro-thermo-mechanical model for stone. The experimental and numerical results indicate that wetting in combination with either decrease or increase of temperature lead to severe damage. The most critical locations for initialization of cracks are sharp spikes (notches), or acute angles that are inward or outward oriented (corners). Stiff but brittle layers, like late diagenetic iron cementations, might be a weak point for the initialization of crack. Furthermore, the bedding direction (anisotropy) seems to be a preferred direction for crack propagation. The results of the numerical analysis are in relatively good agreement with experimental observations.  相似文献   

Ordovician and Silurian lithofacies and base‐metal deposits of the Lachlan Fold Belt     

K. J. Kemežys 《Australian Journal of Earth Sciences》2013,60(1-2):97-107

Two lithofacies maps of the Lachlan Fold Belt, one for the Ordovician and one for the Silurian, are illustrated. Both maps indicate shorelines in western New South Wales, Victoria and Tasmania.

The Ordovicoan map suggests open‐sea conditions eastwards from the shoreline with one major and two minor andesitic volcanoes (or volcanic centres). The Silurian map suggests segmentation of the Lachlan Fold Belt into the Melbourne Basin, Omeo Land, Newell Basin, and Budawang Land. The Newell Basin displays a nearshore (Louth‐Mitta Mitta) coarse clastics facies and an offshore (Wellington‐Cooma) platform carbonate facies. Acid volcanism was widespread over the Newell Basin in Silurian time, but did not occur in the Melbourne Basin.

The Louth‐Mitta Mitta and Wellington‐Cooma facies boundary coincides with the position of the Coolac‐Honeybugle Serpentine Belt and the outcrop area of the Girilambone Beds, suggesting that these features were already in some way prominent during the Silurian Period: the Serpentine Belt may have been a fault, and the Girilambone Beds may have been land.

The origin of base‐metal deposits in the Silurian rocks is thought to be somehow related to the heat generated in the subsurface during Silurian time as is indicated by the volcanism and granite intrusion; and also to the fact that the deposits occur in a transgressive sequence which contains the first phase of acid volcanism in the known geological history of the Lachlan Fold Belt.  相似文献   

Actual state of European wetlands and their possible future in the context of global climate change     

Hana Čížková  Jan Květ  Francisco A. Comín  Raija Laiho  Jan Pokorný  David Pithart 《Aquatic Sciences - Research Across Boundaries》2013,75(1):3-26

The present area of European wetlands is only a fraction of their area before the start of large-scale human colonization of Europe. Many European wetlands have been exploited and managed for various purposes. Large wetland areas have been drained and reclaimed mainly for agriculture and establishment of human settlements. These threats to European wetlands persist. The main responses of European wetlands to ongoing climate change will vary according to wetland type and geographical location. Sea level rise will probably be the decisive factor affecting coastal wetlands, especially along the Atlantic coast. In the boreal part of Europe, increased temperatures will probably lead to increased annual evapotranspiration and lower organic matter accumulation in soil. The role of vast boreal wetlands as carbon sinks may thus be suppressed. In central and western Europe, the risk of floods may support the political will for ecosystem-unfriendly flood defence measures, which may threaten the hydrology of existing wetlands. Southern Europe will probably suffer most from water shortage, which may strengthen the competition for water resources between agriculture, industry and settlements on the one hand and nature conservancy, including wetland conservation, on the other.  相似文献   

Evaluation of inductive logic programming for information extraction from natural language texts to support spatial data recommendation services     

Domen Smole  Marjan Čeh  Tomaž Podobnikar 《International journal of geographical information science》2013,27(11):1809-1827

In this article we analyze a well-known and extensively researched problem: how to find all datasets, on the one hand, and on the other hand only those that are of value to the user when dealing with a specific spatially oriented task. In analogy with existing approaches to a similar problem from other fields of human endeavor, we call this software solution ‘a spatial data recommendation service.’ In its final version, this service should be capable of matching requests created in the user's mind with the content of the existing datasets, while taking into account the user's preferences obtained from the user's previous use of the service. As a result, the service should recommend a list of datasets best suited to the user's needs. In this regard, we consider metadata, particularly natural language definitions of spatial entities, a crucial piece of the solution. To be able to use this information in the process of matching the user's request with the dataset content, this information must be semantically preprocessed. To automate this task we have applied a machine learning approach. With inductive logic programming (ILP) our system learns rules that identify and extract values for the five most frequent relations/properties found in Slovene natural language definitions of spatial entities. The initially established quality criterion for identifying and extracting information was met in three out of five examples. Therefore we conclude that ILP offers a promising approach to developing an information extraction component of a spatial data recommendation service.  相似文献