Entity

Time filter

Source Type


Hanel M.,Czech University of Life Sciences | Hanel M.,T. G. Masaryk Water Research Institute | Buishand T.A.,Royal Netherlands Meteorological Institute
Journal of Hydrology | Year: 2012

This paper presents an analysis of seasonal precipitation extremes in an ensemble of fourteen transient regional climate model (RCM) simulations for durations varying from 1 to 30. days. It is assumed that these precipitation maxima follow a generalized extreme value (GEV) distribution with time-varying parameters. In addition, spatial pooling of the maxima at various grid boxes is applied to reduce the uncertainty of the parameters of the GEV model. Relatively large positive biases in moderate quantiles of long-duration precipitation extremes have been found in autumn, winter and spring. The extreme quantiles are much better reproduced in these seasons. In summer, the ensemble mean bias in the quantiles is negative and decreases (in absolute value) with increasing duration. The ensemble mean changes in the quantiles are positive for all durations, return periods and seasons considered. Large quantiles of the distribution of summer precipitation extremes increase more than moderate quantiles and this increase is relatively large at short durations. The dependence of the changes on duration and return period is much weaker in the other seasons, in particular in winter and spring. Although the spread in the RCM ensemble is considerable, most of the RCM simulations agree on the sign of the changes. © 2011 Elsevier B.V. Source


Stastny J.,Charles University | Stastny J.,T. G. Masaryk Water Research Institute
Fottea | Year: 2010

The present work summarizes the current diversity, distribution and autecology of desmids found within the Czech Republic; the focus is on the occurrence and autecology of rare taxa. Data are based on the author's extensive sampling from 2003-2009, during work for both his master's degree, and currently, his Ph.D. dissertation. Over 1 400 samples were collected, from various types of wetland habitats ranging from eutrophic fishponds, diverse bogs and fens, to ephemeral pools and various aerophytic habitats. Altogether, 526 taxa of desmids (401 species) belonging to 27 genera were found, 80 of them newly described in the Czech Republic. In the present work, 169 rare or otherwise noteworthy taxa, belonging to the following genera: Mesotaenium (1), Netrium (1), Roya (2), Tortitaenia (1), Gonatozygon (2), Closterium (14), Haplotaenium (2), Pleurotaenium (3), Docidium (1), Actinotaenium (6), Euastrum (9), Micrasterias (7), Cosmarium (78), Xanthidium (7), Staurodesmus (4), Staurastrum (25), Cosmocladium (2), Sphaerozosma (2), Hyalotheca (1) and Desmidium (1) are depicted by line drawings and briefly discussed with regard to their ecology, taxonomy or distribution within the Czech Republic or Central Europe. In addition, SEM images are provided for 45 taxa, and, finally, a comprehensive table is included with indicative notations concerning all taxa found. © Czech Phycological Society. Source


Hrncir M.,Czech Technical University | Sanda M.,Czech Technical University | Kulasova A.,T. G. Masaryk Water Research Institute | Cislerova M.,Czech Technical University
Hydrological Processes | Year: 2010

The study is focused on runoff formation processes at two scales: the scale of a small mountainous catchment at its outlet and the scale of an experimental plot located in a typical hillslope subregion. The heterogeneous soil profile of the catchments is formed by Cambisols developed on granite bedrocks. The surface runoff appears rarely, the subsurface flow forms a dominant part of the hydrograph. From the period 1998-2008, a set of 44 rainfall-runoff episodes was selected to analyse the rainfall-runoff relationship using multiple regression analysis. From a set of physical parameters, the initial soil water content came out as the statistically significant parameter that controls the runoff forming process at the catchment scale. The rainfall-runoff relationship at the experimental plot scale is more scattered. The dynamic thresholds of rainfall totals apparently control the ratio and the magnitude of stormflow at both scales. Up to the threshold value, the runoff strongly depends on the initial saturation conditions. Above the threshold value, the initial soil moisture conditions are less important. Copyright © 2010 John Wiley & Sons, Ltd. Source


Hanel M.,T. G. Masaryk Water Research Institute | Hanel M.,Czech University of Life Sciences | Hanel M.,Technical University of Liberec | Maca P.,Czech University of Life Sciences
Hydrological Processes | Year: 2014

Rain event characteristics are assessed in a 10-year (1991-2000) record for 122 stations in the Czech Republic. Individual rain events are identified using the minimum interevent time (mit) concept. For each station, the optimal mit value is estimated by examining the distribution of interevent times. In addition, various mit values are considered to account for the effect of mit on rain event characteristics and their interrelationships. The interdependence between rain event characteristics and altitude, average rainfall depth, and geographic location are explored using simple linear models. Most rain event characteristics can be to some extent explained by average total rainfall or altitude, although models including the former significantly outperformed models using the latter. Significant correlation was found among several pairs of monthly mean characteristics often including event rain rate (with event duration, depth, maximum intensity, and fraction of intraevent rainless periods). Moreover, strong correlation was revealed between number of events, interevent time, event depth, and duration. In general, correlation decreases in absolute value with mit. Strong spatial correlation was found for the mean monthly interevent time and number of events. Spatial correlation was considerably smaller for other characteristics. In general, spatial dependence was smaller for larger mit values. © 2013 John Wiley & Sons, Ltd. Source


Baker D.R.,University of Huddersfield | Ocenaskova V.,T. G. Masaryk Water Research Institute | Kvicalova M.,T. G. Masaryk Water Research Institute | Kasprzyk-Hordern B.,University of Bath
Environment International | Year: 2012

This manuscript reports, for the first time, a monitoring study analysing wastewater and associated suspended particulate matter (SPM) to determine the concentration of drugs of abuse and metabolites in wastewater influent. The monitoring of SPM is crucial for target analytes because, depending on their physico-chemical properties, they may partition to particulates; thus, analysis of wastewater only will result in under-reporting of the concentration of target analytes in the sample. A daily one week monitoring study was carried out at a WWTP serving one of the largest cities in the Czech Republic; representing the first comprehensive application of the sewage epidemiology approach in the Czech Republic. In total, 60 analytes were targeted in the monitoring programme including stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors and their metabolites. Analysis of SPM determined that significant proportions of some compounds were present on the solids. For example, 21.0-49.8% of the total concentration of EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) in the sample was determined on SPM and 11.2-19.6% of methadone. The highest proportion on SPM was determined for fluoxetine in the range 68.1-79.6%, norfluoxetine 46.6-61.9% and amitriptyline 21.8-51.2%. In contrast, some compounds presented very little partitioning to SPM. Less than 5% was determined partitioned to SPM over the week period for analytes including cocaine, benzoylecgonine, cocaethylene, amphetamine, methamphetamine, MDMA (3,4-methylenedioxymethamphetamine), codeine, dihydrocodeine, tramadol, nortramadol, oxazepam and ephedrine. Determined concentrations in wastewater influent were subsequently utilised in the sewage epidemiology approach to estimate drug consumption, in the community from which the wastewater was derived. This back-calculation was updated for the first time to include the concentration of analytes present on SPM. The consumption of methamphetamine and MDMA was determined to be especially high in the studied community in relation to other European countries, while cocaine and methadone consumption was relatively low. This manuscript shows that in order to apply the sewage epidemiology approach, SPM analysis is required for some compounds; whereas for others the partitioning is small and one may regard this as negligible. © 2012 Elsevier Ltd. Source

Discover hidden collaborations