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Determination of evapotranspiration from small catchments
Toušková, Jitka ; Šípek, Václav (advisor) ; Možný, Martin (referee) ; Brom, Jakub (referee)
Evapotranspiration (ET) plays a significant role in the hydrological balance. The terms potential (PET) and reference (RET) evapotranspiration are often used while estimating its rate. The doctoral thesis deals with the estimation of PET, RET and other selected processes. First, the influence of net longwave radiation (the component of radiation balance) on the rate of PET was examined. It was found that the standard methods result in the significant differences in PET estimation due to the absence of model calibration to local conditions. The original model caused distinction in the PET evaluation for the Liz experimental catchment by up to 100 mm/year. Calibration of the parameters of two commonly used methods for calculating net longwave radiation reduced the error in PET evaluation to less than 20 mm/year. PET or RET estimation itself can be performed by many direct or indirect methods. Their accuracy is highly discussed. This work focused on selection of suitable methods and their further testing on conditions of 18 stations in the Czech Republic. 37 methods were compared with measured data. It was proven, that the best results in this region were achieved by combination methods (with average RMSE of 1.2 mm/day, 18.6 mm/month, and 33.3 mm/year). Among individual models, the radiation-based...
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Summary of a potential evapotranspiration calculation methods in the selected river basins
Bedáňová, Jana ; Benáčková, Kateřina (referee) ; Marton, Daniel (advisor)
The master's thesis deals with the research of available methods for calculating potential evapotranspiration and the subsequent application of selected methods. The text part describes general knowledge about evapotranspiration, specific types of vapors from different surfaces (water, soil, vegetation, snow cover, urbanized area). The following are methods of direct measurement, where the types of vapor meters are described, for which types of vapors they are used. Indirect measurement methods for determining potential evapotranspiration and their distribution are also described here. The main part of the research is empirical methods for calculating potential evapotranspiration, here is a selected list of these methods. Furthermore, a practical application of the method according to Thornthwaite, Hargreaves-Samani and Hargreaves-Allen is carried out using data from the Olomouc-Holice precipitation station, the data of which are available from the ČHMÚ portal. Then a comparison of the used calculation methods is made.
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Modeling hydrological response of the catchment to various precipitation events
ŠVANDA, Dominik
This thesis deals with the simulation of the hydrological response of a river basin to various precipitation events. The hydrological response was simulated in the Olešenský brook basin. The outflow of water from the landscape is influenced by many different factors at the same time. Among the most important factors are, for example, the slope of the terrain, land use, saturation of the soil profile withwater, anthropogenic influences, vegetation cover and last but not least the geological and soil conditions, the shape and area of the river basin, climatic conditions etc. explained and described in detail. Several methods are used to calculate the water runoff from the landscape, in which case the CN curve method was used to calculate the direct runoff from the landscape. By using the BPEJ map, land use and maximum daily precipitation totals with a probability of repeating N years (2, 10, 20, 50 and 100 years) obtained from the rainfall station Týn nad Vltavou, calculations were performed first in a numerical (vector) way and then the maps of direct water runoff from the catchment area were created in a raster way performed in ArcMap software. In the next step, various scenarios were simulated that influenced the outflow of water from the catchment. The first scenario was a change in soil saturation with water, resp. water content in the soil (dry, medium and wet). It has been found that the outflow of water from the basin and the peak flow were both fundamentally changed. Second scenario was grassing of all arable land in the basin, where the actual state compared to the theoretical state. This change reduced the CN curve values, what in turn reduced the direct water runoff from the landscape. Third and the last scenario was the concept of 20 metres wide infiltration strips along roads, watercourses and water areas. The proposed measure reduced the runoff coefficient values by about 1 % compared to the runoff coefficients at the actual state. In this case, there was no fundamental change as the strips occupy only a small part of the total area. However, infiltration strips still have a positive effect on rainfall-runoff events in the landscape.
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Bank infiltration in area of Jordán meander on Orlice river
Drmota, Adam ; Hrkal, Zbyněk (advisor) ; Slavík, Martin (referee)
This thesis deals with the study of the Jordán meander on the Orlice River, where the watercourse has undergone extensive revitalization in recent years, which after several decades returned the watercourse to its original riverbed. In connection with the revitalization of the watercourse, an increase in the level of groundwater in the surrounding quaternary aquifer was expected. In this case we can call it artificial bank infiltration. In order to confirm this assumption, hydrogeological boreholes HV1 to HV4 were placed at the site, and they were used for groundwater level monitoring since year 2018. The results of the monitoring document the positive impact of the revitalization on the level of groundwater in the surrounding river alluviums. Furthermore, it was found that boreholes on different banks of the Orlice River react to flow rates in the river and revitalization measures, quite differently. Differences can also be caused by orders of magnitude different hydraulic parameters on both banks, which have been verified using field pumping tests. Keywords: Bank infiltration, monitoring, pumping tests, revitalization
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Optimization of digital river network and its impact on catchment water management
Hošek, Zdeněk ; Matoušková, Milada (advisor) ; Šípek, Václav (referee)
Digital river network dataset is an important source of information in any aspect of water management decision making. It is also a base for modelling or scientific research in many different fields. Development of the dataset in the Czech Republic had been fragmented in a past and as a result three different datasets have been developed that cover the whole of the state's territory. The datasets contain different geometries, different and often conflicting attributes and serve different purposes. Today the time has come that water management decision makers have realised that the situation is no longer sustainable and make effort to merge the datasets into one. The task brings in several technical issues and a potential for severe legal consequences. The aim of this study is to develop a methodological approach to merging the existing datasets into one. This methodological approach to decision which of the conflicting or different attributes should be adopted is based on assumption that the existing datasets will be merged into one consisting the best of all. Comparison of features in the existing dataset will inevitably lead to many conflicts when it will be necessary to decide which of the considered features should be adopted to the resulting dataset. The study considers the main purposes which...
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Optimization of digital river network and its impact on catchment water management
Hošek, Zdeněk ; Matoušková, Milada (advisor) ; Šípek, Václav (referee)
Digital river network dataset is an important source of information in any aspect of water management decision making. It is also a base for modelling or scientific research in many different fields. Development of the dataset in the Czech Republic had been fragmented in a past and as a result three different datasets have been developed that cover the whole of the state's territory. The datasets contain different geometries, different and often conflicting attributes and serve different purposes. Today the time has come that water management decision makers have realised that the situation is no longer sustainable and make effort to merge the datasets into one. The task brings in several technical issues and a potential for severe legal consequences. The aim of this study is to develop a methodological approach to merging the existing datasets into one. This methodological approach to decision which of the conflicting or different attributes should be adopted is based on assumption that the existing datasets will be merged into one consisting the best of all. Comparison of features in the existing dataset will inevitably lead to many conflicts when it will be necessary to decide which of the considered features should be adopted to the resulting dataset. The study considers the main purposes which...
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The assessment of change in the water balance of Hačka catchment due to the climate change
Moravec, Vojtěch ; Hanel, Martin (advisor) ; Ladislav, Ladislav (referee)
In the presented paper the changes in mean runoff, temperature and precipitation totals in
an observed period 1962-2015 in the catchment river Hačka are assessed. The paper further
presents the analysis of climate change impact on mean runoff between the periods 1984-2014
(control period) and 2035-2065 and 2068-2098 (scenario periods) using the projections of three
regional climate model simulations. Thin Plate Spline interpolation was used to estimate basin
precipitation and temperature. Modified hydrological analogy was used for precise quantification
of naturalized runoff (i.e. not affected by water use). Climate change scenarios were
derived using simple delta change approach, i.e. observed series of precipitation and temperature
were adjusted in order to give the same changes between the control and scenario period
as regional climate model simulations. Hydrological balance was modelled with a conceptual
hydrological model Bilan. The parameters of the hydrological model were estimated using observed
data. These parameters were subsequently used to derive discharge series under climate
change conditions for each regional climate model simulation. Results showed a 1.7 °C average
increase in mean annual temperature in the scenario period 2035-2065 and a 2.8 °C average
increase in the scenario period 2068-2098. The seasonal cycle of precipitation in the scenario
conditions is shifted, although mean annual precipitation totals remain practically unchanged
(max changes -8.1 %; +9.3 %). The mean annual discharge decreases by 5.7% in average (most
20.3 %) in period 2035-2065 and a significant decrease of 25.5% in average (most 45.9 %) in
annual mean discharge is expected in the period 2068-2098. Frequency of minimal runoff is expected
to increase up to two times. Precipitation increase is expected from the beginning of the
fall to the beginning of the summer, with a slight decrease in spring. Increase in precipitation
is followed by evapotranspiration increase, caused by increase in temperature. Summer precipitation
is expected to decrease as well as summer runoff. Due to the temperature increase, time
shift of the snowmelt is expected from the periods between March-April to January-February.
This will also affect the increase of the discharge in this period. This knowledge can be applied
in water management planning in the future.
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Factors affecting the water discharge from the river basin during rainfall-runoff events
TICHÁČEK, Pavel
This thesis focuses on the factors affecting runoff water from the basin during the rainfall-runoff events. Work begins by describing the circulation of water in nature and continues with hydrological balance. Next chapter is the formation of precipitation and water runoff, in which the water outflow is divided into surface and subsurface. In the work is characterized runoff process and there are described factors that affect water runoff from the watershed. The last part describes the possibility of using these factors for creating erosion and flood control.
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Factors affecting the total outoff from the watershed and its individual components
MORAVCOVÁ, Lenka
This thesis is focused on the topic of total outflow from the watershed. In the first part water is divided into surface water, subsurface and groundwater, there is also described water circulation, hydrological balance, water retention and water accumulation, as well as characteristics of hydrographic network in the country. There are listed and explained outflow folders and measures to reduce surface runoff. In the second part of this work methods of separating the individual components of outflow, such as CN-method, Kliner and Kněžek method, model SMODERP, HYDROG model, GROUND and MGPM methods are described. In the conclusion it is explained that outflow from the watershed generates not only because of rainfall, but also due to geological, pedological, anthropogenic and other factors.
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Base flow-separation method, factors affecting the incidence and size
VLASÁK, Ivo
This bachelor thesis focuses on hydrological cycle, hydrological balance and hydrology of underground waters. Underground waters holding in a river stream is one of the most important characteristics of hydrological mode of a river. Underground waters proportion is detected from a line of flow rate in the course of many years via so called separation of underground river stream. There are several methods of separation and problematics of these methods is described in detail in this thesis. What is mentioned further are the factors influencing occurance and size of an elemental outflow rate, these factors being in particular climate, geology,relief of land, vegetation and last but not least human aktivity. Outflow rate which comes through the cycle of underground waters can be considered as an elemental outflow rate. Outflow rate is a subject matter of a further chapter. Water flowing out in a form of an elemental outflow rate creates both surface and underground waters, which are constituents of a cycle of water in the nature, which is described in this thesis in a detail together with surface, underground and subsurface water.
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