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Evapotranspiration impact on hydrological modeling
Macounová, Anna ; Daňhelka, Jan (advisor) ; Kimlová, Martina (referee)
This work presents the evapotranspiration from the point of view of its impact on hydrological modeling. We have tested the influence of different input evapotranspiration on the simualtion outputs of rainfall-runoff model Sacramento (SAC-SMA), which is the component of the hydrological forecasting system AquaLog used for flood forecasting in the Czech part of Elbe river basin. Litavka river basin was selected for this case study. We present physical geographical characteristics of the basin from the poin of view of influence of the evapotranspiration rate. Simulation using different computed evapotranspiration daily timeseries for 2001 - 2005 inputted SAC- SMA and total runoff, runoff composition, zones saturation were evaluated. Results proved that SAC- SMA sensitivity to evapotranspiration is of great concern especially for the long time and slow developing processes in the basin. Evapotranspiration loss, base flow generation and connected saturation of tension water zones and lower zone primary free water were identified to be the most affected states and processes. Powered by TCPDF (www.tcpdf.org)
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Modeling the impact of small water reservoirs on flood events
Taufmannová, Alice ; Jeníček, Michal (advisor) ; Daňhelka, Jan (referee)
This paper deals with evaluating the impact of small reservoirs on flood events. The system of small reservoirs represents an effective part of integrated flood protection in the Czech Republic. Its realisation does not require a drastic impact on the environment. The small reservoirs could influence significantly the decrease of flood flows in the mountain catchments. Four small potential uncontrolled reservoirs were implemented to the headwater part of the Rolava river basin (126 km2) in the Ore Mountains. The relief of the Rolava river basin is heterogeneous with the upper headwater part characterised as flat plain and the middle part of the river flowing through a steep valley. The only option of the river to be flooded out during the extreme floods could appear in the lower part of the river basin. The Rainfall-runoff modeling was carried out in the model HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System). The advantages of the model are its freeware availability, good arrangement and connection with GIS. The basin model of Rolava was calibrated using the known flood event in September 2007. The verification of the basin model ran on flood event in August 2006. The value of the efficiency criterion between the simulated and measured hydrograph was 0,86 and 0,89, which means successful...
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Modelling snow accumulation and melting in the Bystřice River basin
Kutláková, Lucie ; Jeníček, Michal (advisor) ; Daňhelka, Jan (referee)
Dealing with the issue of spring flood events is primarily based on their causes. It is therefore important to study the processes of snow accumulation and snowmelt especially in mountain areas where the development of snow water equivalent (SWE) is primarily observed. The snow water equivalent indicates amount of the water in the snow and thus represents a runoff volume during the spring melting period and demonstrates the flood risk potential. In this thesis the lumped modelling approach of the rainfall-runoff model HEC- HMS was used. The model was applied in the Bystřice River basin in the Ore Mountains where the field measurements of the snow cover and SWE is carried out. Applied temperature-index method is the well-developed method because it takes into account both the melting during precipitation and melting in the period without any precipitation and aims to capture snow energy balance by means of air temperature. Three winter periods (2006, 2008 and 2009) were simulated. The evolution of the snow water equivalent was observed and the agreement between observed and simulated hydrographs was assessed in the closure profile Ostrov. Published results show the influence of winter course and character on the model capability to simulate the snow water equivalent and runoff. The observed and...
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Mean areal precipitation method impact on runoff simulation
Janková, Jana ; Daňhelka, Jan (advisor) ; Čekal, Radek (referee)
Work presents physical geography of the Úpa River basin from the point of view of geology, geomorphology and soil characteristics. Climate, hydrography and hydrology are described in more detail. Úpa River basin is specific in its shape and position in the headwater where runoff is generated. Four sub-basins (Horní Maršov, Horní Staré Město, Slatina nad Úpou and Zlíč) were used for evaluation of mean areal precipitation (MAP) computation method impact on simulated flows. MAPs were computed for four intense rainfall episodes using arithmetic, Thiessen polygon and different settings of inverse distance method (= 2 or 3). These MAPs enter into hydrological forecasting and modeling system AquaLog that includes rainfall runoff model SAC-SMA. AquaLog and SAC-SMA are also described in this thesis. Modeled runoff series (based on different initial conditions) were analyzed in the meaning total runoff, peak flow, and fast runoff components (surface, sub-surface and direct). Results show that optimal results in the higher part of the basin provide inverse distance method with set to 3. Powered by TCPDF (www.tcpdf.org)
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Evaluation of precipitation forecast from the point of view of hydrological forecasting in small catchments
Pecha, Martin ; Daňhelka, Jan (advisor) ; Čekal, Radek (referee)
In this work we have evaluated NWP ALADIN quantitative precipitation forecast (QPF) for selected headwater areas of the Czech part of the Elbe river basin. Work describes geographical characteristics of 9 small study basins, and gives an overview of important synoptic situations and theory of NWP ALADIN. Different applied statistical methods (f.e. double mass curve, CDF, frequency diagram, discrimination and reliability) are introduced. Results have proved over-forecasting of days with precipitations especially those of light precipitation up to 1 mm and partly also up to 5 mm. On the other hand basins that are not exposed to prevailing western flows show under-forecasting of precipitation higher than 8 mm. Evaluation also proved the significant change in forecasting performance due to change in model resolution in 2005. The change was more significant in basins exposed to west and in basins in middle altitudes and spatially limited highlands. Simple quantile transformation resulted in improvement of forecast of total long term volume of precipitation in most of the study basins. Powered by TCPDF (www.tcpdf.org)
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Runoff generation in urban environment
Píchal, Jan ; Daňhelka, Jan (advisor) ; Čekal, Radek (referee)
As the area of impervious surfaces at urban environment increases, the more rapid runoff and urban flash floods lead to frequent overflow of the sewer system. For storm water runoff prevention and mitigation, there are soakaways commonly built in newly build up areas. The soakaways volume calculation is given by ČSN 75 9010 regulation in the Czech Republic. The presented thesis verifies applicability of this regulation in selected study sites (smal basins) of projected building construction model basins, which differ with regard to their infiltration characteristics, slope, area and degree of planned urbanization. The runoff calculation was estimated by Clark's Unit Hydrograph (UH) transformation and triangular SCS UH. HEC-HMS software has been used for Clark's UH application. Triangular UH runoff calculation has been done using MS Excel environment to establish a series of equations and logical conditions. Both models' results were compared for storms with 5 years, 10 years, 100 years and theoretical maximum return period; thus also for storms with longer return period than is proposed in the regulation. The positive differences in soakaway peak overflows and peak runoffs in study sites before the start of the urbanization were compared and evaluated, together with the differences in soakaway...
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Snow water content modelling in small catchments
Němečková, Klára ; Daňhelka, Jan (advisor) ; Bercha, Šimon (referee)
Title: Snow water content modelling in small catchments This work deals with modeling of amount of snow cover, snow water equivalent, respectively, on an experimental catchment in the Jizerské hory Mts. Measuring and modelling of the snow cover is an important part of water management practice from the perspective of reservoir operation and flood management. The first part of this thesis describes physical-geographical characteristics of the Jizerské hory Mts.especially from the climatological and hydrological point of view but also other charakteristics and conditions that may affect the dynamic of snow accumulation and melting are described with detailed focus on the experimental catchment of Černá Desná river - Jezdecká. Two modelling approaches were applied to simulate snow water equivalent (SWE) based on observed precipitation and temperature. Beside the well knowen SNOW17 model a simple method based on heat index was developed in this work and its parameters were calibrated based on measured timeseries of daily average air temperature, daily precipitation and observed SWE for winter periods 2001 to 2009. Both methods provided reasonably accurate estimates of SWE over the tested period, however it was found that the results for winters with extreme conditions (very warm or very cold) are less...
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Small water reservoirs in the Krkonoše Mountains: What would their regeneration bring?
Šádková, Eva ; Janský, Bohumír (advisor) ; Daňhelka, Jan (referee)
This thesis deals with the evaluation of influence of small water reservoirs on the extreme runoff events (floods and drought) in the upper Úpa River basin. It summarizes knowledge about both hydrological extremes and their manifestations in the basin of interest as well as about small water reservoirs in the sense of water retention measures and their possible importance during the periods of low flows or floods. In this thesis two localities of possible reservoirs at place of former splash dams in Obří důl and on the Lysečinský Brook were chosen. To assess the influence of small water reservoirs on runoff during two chosen flood events and two periods of drought, the hydrological model HEC-HMS was applied. The results of model simulation proved a positive influence of reservoirs on the reduction of flood peaks (except for a concurrence of transformed flood waves in the outlet that occurred during one flood event), but the effect was decreasing with the increasing catchment area and the intensity of precipitation and with smaller storage capacity of a reservoir. During the low flows, a positive influence of reservoirs was observed as well, relating to the release of stored water. However, the ability of a reservoir to reduce deficit volume and to balance the flow was decreasing with smaller...
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