The objective of the study was to evaluate the spatial distribution of peakflow pre-event water contributions and streamwater residence times with emphasis on land use patterns in 38 subcatchments within the 687 km2 large mesoscale transboundary catchment Lužická Nisa. Mean residence times between 8 and 27 months and portions of pre-event water between 10 and 97% on a storm event peakflow were determined, using 18O data in precipitation and streamwater from a weekly monitoring of nearly two years. Only a small tracer variation buffering effect of the lowland tributaries on the main stem was observed, indicating the dominant impact on the mountainous headwaters on the runoff generation. Longest mean streamwater residence times of 27 months were identified in the nearly natural headwaters of the Jizera Mountains, revealing no ambiguous correlation between the catchment area and altitude and the mean resi-dence time of streamwater. Land use control on the pre-event water portions were determined for three land use catego-ries with percentage of urban areas from 0 to 10%, 10 to 20% and more than 20%. The fraction of pre-event water in the first category decreases from 97% to 65% with the increasing percentage of forest from 76% to 100%, revealing that for-ests may provide only a limited infiltration of precipitation due to leaf interception and soil water use for transpiration. Fractions of pre-event water of 39–87% in the second (agricultural catchments) and of 10–35% in the third (urbanized catchments) category increase with percentage of non-urban areas.
The article concerns two basic approaches to the problem of epistemic belief-justification: internalism and externalism. It aims to show that internalism as wel as externalism, when confronted with the problem of philosophical skepticism, face various kinds of problems, which lead to implausibility of their respective accounts of justification. The author focuses especially on the externalist approach which was invented as a direct response to the threat of skepticism. The central part of the article contains a brief analysis of main attributes of externalism, and subsequently its criticism which aims to show that the criteria of justification proposed by externalists do not accomplish the basic function of distinguishing between justified and unjustified beliefs. The author argues that the discussed deficiencies of externalism result from its elementary rationale, which implies that they are incurable, and therefore the externalist criteria of justification inevitably fail., Článek se zabývá dvěma základními přístupy k problematice ospravedlnění epistemické víry: internalizmu a externalismu. Jejím cílem je ukázat, že internacionalismus, stejně jako externismus, když je konfrontován s problémem filosofického skepticismu, čelí různým druhům problémů, které vedou k nepravděpodobnosti jejich příslušných zpráv o ospravedlnění. Autor se zaměřuje především na externalizační přístup, který byl vynalezen jako přímá reakce na hrozbu skepse. Ústřední část článku obsahuje stručnou analýzu hlavních atributů externalismu a následně jeho kritiku, jejímž cílem je ukázat, že kritéria ospravedlnění navrhovaná externisty neplní základní funkci rozlišování mezi oprávněnými a neopodstatněnými vírami., and Martin Nuhlíček