National Repository of Grey Literature 23 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Spatial snow distribution in locality with diverse forest structure in the Sumava Mountains
Švejdová, Klára ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Snowpack is strongly influenced by several environmental factors. Besides meteorological and topographical conditions, vegetation structure plays an important role. The aim of this bachelor thesis was to assess how the canopy structure affects snow distribution. The snow depth and snow water equivalent (SWE) were measured in a selected location situated in the Kvildský potok basin in the Šumava Moutains during the winter season 2019. Canopy structure was described using Leaf Area Index (LAI) obtained from hemispherical images of the area. The degree-day method was used to calculate melt factors. The influence of vegetation was examined by using the correlation and regression analyses. Snow depth and SWE was significantly lower in forest sites than in the open area and in the forest disturbed by the bark beetle (Ips typographus). The influence of canopy structure was highest during snow accumulation and its importance decreased with time. The SWE variability was largest for last measurement during the melt phase. Melt factor calculated for period between last two field measurements was 2.3 mm∙řC-1 ∙d- 1 .
Usage of meteorological data in hydrological modelling (case study in upper Vydra catchment)
Vlček, Lukáš ; Šípek, Václav
This paper deals with an evaluation of runoff formation at a small catchment (0.6 km2) consisting of two dominant soil types of the Vydra headwaters. Several Hydro-meteorological parameters have been measured at the study catchment and used in a hydrological model in an effort to estimate a proportion of surface or subsurface flow components and their effects on the outflow process. Chosen hydrological model showed that a greater proportion of an outflow from the catchment is generated, in general, from a peat bog area, mainly due to the lower evapotranspiration from the peatland compared to the mineral soil. On the contrary, during dry periods most of the outflow comes from a mineral soil and a peat bog contributes only to the outflow from the lower, permanently saturated layer.
Analysis of critical natural occurrence causing cultural heritage hazard
Hnilicová, Soňa ; Šípek, Václav
Floods are one of the most occurring natural hazards causing damage of cultural heritage. Factors influencing flood formation and the shape of flood wave are analysed. Mechanism of complex flood control protection is described including planned and realised measured in the capital city Prague.
Soil water retention in the landscape
Hřebejková, Barbora ; Šípek, Václav (advisor) ; Frouz, Jan (referee)
Water retention in the landscape is one the current topics in environmental protection. It is affected by a number of factors and is changing both in time and space. The goal of this thesis is to examine the long-term development of water retention in the landscape and to determine the influence of different types of vegetation on the soil moisture underneath. In the first part of my thesis I review different soil types with respect to their physical characteristics and interaction with water, and ways of measuring soil moisture. The aim of the thesis is the sum up the basic knowledge about soil and basics behaviour, mainly in the relation with soil moisture. There are introduced methods of soil moisture measurement with regard to their limits. In the second part I focus on analysis of selected studies covering the topic of water retention in the landscape. Due to the technical difficulty is only a few studies devoted to a long term measurement of soil water by direct methods and therefore are results mostly limited to evaluate soil water retention by hydropedological models. In the final part I discuss and evaluate the results of the aforementioned studies. Key words: water retention, soil moisture, evapotranspiration, soil hydrology, climate change
Using ultrasonic snow depth data to minimaze the error in winter precipitaton measurements
Peňáz, Štěpán ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Winter precipitation measurement is more problematic in terms of accuracy than measurement of rainfall precipitation that occur during the rest of the year. The results of rainfall measurements during the winter are significantly influenced by wind, both during the accumulation itself and subsequent redistribution of the snow cover. The aim of this work is to analyze automatically measured data from a heated tipping bucket, ultrasonic snow depth sensor for snow measurement and sensors for measuring snow water equivalent, which aims to determine the dependence of the density of new snow on temperature or humidity and consequently to derive the relation that will serve to refine the quantum estimation of winter precipitation. Based on the correlation and regression analysis of the data, the direct dependence between the density of the new snow and air humidity has not been proven, but the dependence between the density of the new snow and the air temperature has already been proven, though not very significant (Spearman's rank corelation rs = 0.39), this dependence explains approximately 9 % of data variability. The resulting calculated snowfall values in the winter seasons of 2016 and 2017 indicate that the heated tipping bucket has underestimated the amount of precipitation by 50% (2016) and 59%...
Climate change impacts on snow storages and spring runoff in the Vydra river basin
Cuřín, Vojtěch ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Climate change impacts on snow storages and spring runoff in the Vydra river basin Abstract As a result of increasing air temperature, the fraction of precipitation falling as snow decreases. This affects snow cover indicators including snow cover duration, snow cover extent and the amount of water that accumulates in snow cover during winter. These changes further propagate through local runoff process and alter winter and spring runoff. The impacts of air temperature warming of 1℃, 2℃ and 3℃ on the above-mentioned indicators were simulated using a conceptual catchment runoff model HBV-light. Multi- criteria calibration, based on functions describing the goodness of fit of simulated runoff and snow water equivalent (SWE) values was performed. The temperature change scenarios were derived using the delta-change method from reference dataset 1980-2014. The indicator changes were evaluated for 5 elevation belts of the catchment as well as for the catchment as a whole, so that the observed alternations of snow cover indicators could be related to the modelled alternations of runoff. The changes in snow cover characteristics based on these simulations include a decrease of snowfall fraction, shortened snow season, decrease in average and maximal SWE values, and the shift of the average day of year of SWEmax to...
Influence of land cover and altitude on soilmoisturespatio-temporal variability
Šípek, Václav ; Hnilica, Jan ; Tesař, Miroslav
An understanding of spatial and temporal variation of soil moisture is essential for studying other hydrological, biological or chemical soil processes, such as water movement, microbial activity and biogeochemical cycling (Bruckner et al., 1999, Ridolfi et al., 2003). Although the world-wide total amount of water stored in the soil profile is negligible compared to ocean and glacier storages, it represents a crucial variable concerning the water resources and agricultural management. This is valid especially in the context of ongoing shift in climate. Soil water exhibits a tremendous heterogeneity in space and time (Gomez-Plaza et al., 2000). Therefore, spatial and temporal variations of soil moisture have always been the critical issue. The spatial variability is influenced by variety of factors encompassing the topographical effect on lateral water redistribution (Williams et al., 2003), radiation (Grayson et al., 1997, Geroy et al., 2011), soil texture and structure (Famiglietti et al., 1998, Pan and Peters-Lidard, 2008), vegetation (Teuling and Troch, 2005), climate (Lawrence and Hornberger, 2007), precipitation pattern (Keim et al., 2005) and antecedent soil moisture (Rosenbaum et al., 2012). The land use influence on the soil moisture content variation is of complex a character covering several above mentioned factors. However, it is determined namely by the different vegetation cover, which results in different rates of interception and transpiration. It also strongly influences the soil hydraulic properties, i.e. hydraulic conductivity and water retention characteristics (Zhou et al, 2008). Hence, the reaction of an area to a rainfall and also the temporal variability of the soil moisture content might be influenced by the present land cover. Nevertheless, the studies comparing the influence of several land covers in the longer periods are missing. This knowledge would be valuable especially in the context of extreme climatic events that are present nowadays. In central Europe, the period of major floods (1997, 2002, 2013) was followed by serious dry spells (2003, 2011–2012, 2015) (Trnka et al., 2015). This observed hydrological extremity raised the questions of sustainable water management. One of the possible management practices in consideration is represented by the land cover changes intended to hold more water in the landscape and simultaneously to attenuate the rainfall-runoff response. Moreover, previous studies have investigated that spatial and temporal variation of soil water under a certain land use type, and drawing significant research attention is lacking on the differences of dynamics of soil water conditions under different land use types. Thus, it is necessary to understand the comparisons of the dynamics of soil water conditions under different land use types (Niu et al., 2015) The main aim of the presented study is therefore to understand the soil moisture variability in the vegetation season under four different land covers (coniferous/deciduous forest, meadow, grassland). This analysis is conducted in five consecutive years, encompassing both dry and wet periods. The influence of altitude is also studied in the coniferous forest.
Modelling the impact of seasonal snowpack on summer low flows in mountain catchments
Nedělčev, Ondřej ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
This thesis analyses the impacts of winter snowpack and subsequent spring and summer liquid precipitation on low flows in the warm season. Meltwater is an important source of groundwater recharge. From groundwater storage streams are donated during summer months. Snow accumulation during cold season is reduced and snowmelt occurs earlier, which is a result of climate change and leads to lower groundwater recharge rates. That is the reason why change in snow cover dynamics affects summer low flows. Main goals of this thesis are to analyse how snow cover affects low flows I warm season and to compare it with impact of spring and summer precipitation. A conceptual runoff model HBV-light has been used to simulate the snow water equivalent (SWE) and streamflow from three mountain catchments. The integrated multi-variable model calibration procedure was used to calibrate the model. The model was used to simulate the snow and streamflow from 1981 to 2014. Besides the mentioned simulation, two hypothetical scenarios have been performed. These two scenarios accounted for reduced spring and summer liquid precipitation. In the first scenario, precipitation after maximum annual SWE was reduced to 75% of the real measured precipitation. In the second scenario, precipitation was reduced to 50% of the real...
Retention capacity of flood plain and alternative flood protection in the Berounka River catchment.
Pergl, Michal ; Matoušková, Milada (advisor) ; Šípek, Václav (referee)
This thesis deals with the retention capacity of Berounka during the hydrological extremes. Flood prevention and flood condition are main subjects of this thesis. Two selected river areas of Berounka are analysed by the passive retention volume and by the transformation of the flood wave. The first area is situated on the lower course of Berounka near the Černošice, and this area is significantly anthropogenically influenced. The second area which has nature character is located on the middle course of Berounka near Křivoklát. This thesis contains an evaluation of the hydromorphological state of flow in both areas. The results of passive retention indicate negligible influence of the flood situations. 1D hydraulic model HEC-RAS displays the transformation of the flood wave. The results of the transformation are flow velocity and depths of the river valley in 100-year-old and 20-year-old flows. The transformation of the flood wave in the first area is on the minimum level and did not reach its potential retention capability. The culmination flow in the second area is reduced because of a geomorphological shape of the river. Moreover, the near natural flood protection precautions are proposed in this thesis. Mean flow velocity in 100-year floods could be reduced by 1 - 1,6 m.s-1 by forestation of...

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2 Šípek, Vojtěch
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