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  • Author or Editor: Silvia Kohnová x
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Abstract

Regional flood frequency analysis is considered to be an important and popular method for estimating different hydrological variables at ungauged sites. The estimation of the index flood is the essential problem when this method is applied. The objective of the study is a comparison of the estimation of the mean annual flood (or index flood) by using two approaches based on the ‘so-called’ index flood method and top-kriging. The concept behind these methods permits estimating the mean annual flood at ungauged locations using information taken from gauged sites located within the same homogeneous pooling groups. The study area comprises 104 gauging stations on the whole territory of Slovakia. The observation period of the annual maximum discharges of the selected stations was from 1961-2010. The identification of the homogeneous pooling group was performed using a non-hierarchical k-means clustering algorithm. The optimal number of clusters is determined by the Silhouette method. As a result, eight homogeneous pooling group clusters were identified. Finally, the results of the estimated mean annual floods using the index flood method and top-kriging were compared with the observed data. Top-kriging provided better results than the classical index flood method for estimating the mean annual flood at ungauged sites.

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Abstract

The paper focuses on future changes in the short-term rainfall intensities in the western region of Slovakia. The analysis was performed for 4 climatological stations, namely: Malacky, Myjava, Vrbovce and šaŠtín. The short-term rainfall intensity data from the community land model that is a regional climate model were used in durations of 60 to 1440 minutes for a warm period. The focus was aimed at comparing changes in rainfall characteristics, especially changes in the seasonality and trends and changes in the scaling exponents and design values.

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The study focuses on an analysis of the future changes in short-term rainfall in the southwestern region of Slovakia. The analysis was performed for three climatological stations, i.e. Bratislava-Koliba, Gabčíkovo and Sereď, where short-term rainfall intensities with durations of 60 to 1440 minutes were analyzed using historical observations and future regional climate models. The study focuses on detecting changes in rainfall trends and changes in the values of the scaling coefficients. In final, there is a comparison of the design values of short-term rainfall derived for a future horizon with historical observations and the conclusion that rainfall intensities in the region analyzed will increase in the future and that this should be taken into consideration when designing water structures to ensure their safety.

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Pollack Periodica
Authors: Gabriel Földes, Silvia Kohnová, Marija Mihaela Labat, and Kamila Hlavčová

The paper focuses on the impact of climate change on runoff in the Ipoltica River basin in northern Slovakia. The analysis is divided into two parts: the first part contains an analysis of predicted changes in short-term rainfall intensities at the Liptovská Teplička climatological station; the second part is focused on the impact of runoff on a small mountainous river basin. The predicted short-term rainfall intensities were analyzed using the Community Land Model, which is a Regional Climate Model. The analysis was performed in durations of 60 to 1440 minutes for a warm period. The focus was aimed at comparing changes in rainfall characteristics, especially changes in seasonality, the scaling exponents, and design values. The second part focuses on the impact of changes in short-term rainfall on changes in runoff. The estimation of predicted runoff changes was provided for the period 2070 - 2100. These results were compared with the results from actual observations. The design floods were calculated using the Soil Conservation Service - Curve Number method. The results show that the runoff will be affected by climate change. Hence, it is important to reevaluate the land use management and practices at the Ipoltica River basin.

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Abstract

The objective of the study is an assessment of a Ratka small water reservoir in Slovakia by using two main aspects, i.e., the hydrotechnical, geotechnical and environmental aspects.

An evaluation of the actual state of a small water reservoir was solved in a complex way. Based on the field measurements, the quality of surface water was controlled in order to check if the surface water quality indicators meet the requirements of government regulations. In addition to the terrain measurements, laboratory measurements were performed. The results assess the actual state of the small water reservoir in details, including an assessment of the water quality with proposed measures for improving the condition of the water reservoir.

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Pollack Periodica
Authors: David Honek, Zuzana Németová, Silvia Kohnová, and Monika Šulc Michalková

Abstract

The modeling of soil erosion processes is affected by several factors that reflect the physical-geographic conditions of the study site together with the land use linkage. The soil parameters are significant in the modeling of erosion and also runoff processes. The correct determination of a soil's parameters becomes a crucial part of the model's calibration. This paper deals with a sensitivity analysis of seven soil input parameters to the physically-based Erosion 3D model. The results show the variable influence of each soil parameter. The Erosion 3D model is very sensitive to initial soil moisture, bulk density, and erodibility.

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The aim of this paper is an assessment of the susceptibility of soil to soil erosion, proposed measures against soil erosion, and an assessment of their effect on the reduction of peak flows. The area of interest is the Halúzníkov Creek basin. The calculations of the soil loss from water erosion were done using the universal soil loss equation and universal soil loss equation 2D methods; for estimating design floods, the curve number method was applied. For reducing the soil loss to tolerance values, strip cropping measures on agricultural fields were proposed. After applying the strip cropping measures, the design flood peaks were also reduced.

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Pollack Periodica
Authors: Zuzana Németová, David Honek, Tamara Látková, Monika Šulc Michalková, and Silvia Kohnová

The scope of this study is an evaluation of potential soil water erosion using the physically-based erosion model, EROSION-3D. This model is event-based and calculates soil water erosion during an actual measured rainfall event. The calculations of the erosion model take advantage of a digital elevation model, precipitation and soil parameters, which are established in a specific parameter catalogue. The soil water erosion was modeled in two small catchments in the Myjava Hill Land (Slovakia), using 9 soil moisture scenarios and two different crops on arable areas. When considering the last 35 years of rainfall records at the Myjava meteorological station, three storm rainfall events were applied in the modeling. The results were statistically analyzed to figure out the differences between the model’s functional possibilities; the modeling under the various scenarios proved a strong interaction between the values of the input factors and the results of the soil erosion.

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