Ondrej Ledvinka

Czech Hydrometeorological Institute | ČHMÚ · Hydrology Database and Water Budget Department

Hydrological methods based on the analysis of data from a large sample of catchments with different characteristics (large-sample hydrology; comparative hydrology) allow a comprehensive analysis of the hydrological regime and thus a description of hydrological variability and change in the components of the water balance. These methods provide insi...

136 springs in 18 hydrogeological regions (HGR) were selected for analysis of spring yields during the period 1971–2020. Monthly, seasonal and annual trends in yield were evaluated. The majority of springs (71%) showed no long-term trends in annual yields. However, once a statistically significant trend was identified, decreasing yields (28%) outwe...

Hydrological methods based on the analysis of data from a large sample of catchments with different characteristics (large-sample hydrology; comparative hydrology) allow a comprehensive analysis of the hydrological regime and thus a description of hydrological variability and change in the components of the water balance. These methods provide insi...

Megafloods that far exceed previously observed records often take citizens and experts by surprise, resulting in extremely severe damage and loss of life. Existing methods based on local and regional information rarely go beyond national borders and cannot predict these floods well because of limited data on megafloods, and because flood generation...

This work deals with developing an operational approach to utilize the current possibilities of rainfall-runoff modelling for determining the risk of occurrence of flash floods in real-time. The report summarizes the results of research and development stemming from the sub-task “Development of a robust method for estimating runoff from heavy rainf...

Since December 2012, during every winter season, the altitude of the zero isochion (snowline) has been determined at the Czech Hydrometeorological Institute for the purposes of operational hydrology. The reason is the estimation of the amount of water stored in snow cover, which is inevitable activity for Czech hydrologists who naturally want their...

Extreme tree growth reductions represent events of abrupt forest productivity decline and carbon sequestration reduction. An increase in their magnitude can represent an early warning signal of impending tree mortality. Yet the long-term trends in extreme growth reductions remain largely unknown. We analysed trends in the proportion of trees exhibi...

Changes in the frequency, magnitude, and seasonality of hydrological extremes are one of the expected consequences of climate change. Recent years suggested an increasing risk of drought occurrence and restricted water supply even in usually humid mountain regions. Our research is focused on the evaluation of regional climate change and its effect...

In the past few years, demands on flash flood forecasting have grown. The Flash Flood Indicator (FFI) is a system used at the Czech Hydrometeorological Institute for the evaluation of the risk of possible occurrence of flash floods over the whole Czech Republic. The FFI calculation is based on the current soil saturation, the physical-geographical...

In the environment of the changing climate in Central Europe, the seasonality and magnitude of low flow events and hydrological droughts are projected to change in the near future. Ongoing increases in the air temperature, rates of evaporation and decreasing snow cover will significantly affect the summer deficit volumes even in the rivers of humid...

The Ministry of Health in cooperation with other related bodies compiles, on an annual basis, the List of outdoor bathing sites on surface waters where the bathing service is offered by the operator, and other surface waters used for bathing . It is compiled based on the long-term monitoring, performed, exclusively as in-situ measurements, by the r...

The Lusatian Neisse belongs to one of the most important European rivers. Its basin crosses the borders of three countries. In August 2010, the basin experienced disastrous floods that drew attention to this area also of those outside the hydrological community. It seems that the drivers of extreme rainfall events may change here either due to the...

In the context of the ongoing climate warming in Europe, the seasonality and magnitudes of low flows and streamflow droughts are expected to change in the future. Increasing temperature and evaporation rates, stagnating precipitation amounts and decreasing snow cover will probably further intensify the summer streamflow deficits. This study analyze...

Statistical detection of trends in hydrometeorological time series is a crucial task when revealing how river systems react to environmental and human-induced changes. It was shown that the autocorrelation structure of a series influences the power of parametric and nonparametric trend tests. While the order of short-memory processes can be suffici...

The streamflow seasonality in mountain catchments is often influenced by snow. However, a shift from snowfall to rain is expected in the future. Consequently, a decrease in snow storage and earlier snowmelt is predicted, which will cause changes not only in seasonal runoff distribution in snow-dominated catchments, but it may also affect the total...

This study investigates changes in seasonal runoff and low flows related to changes in snow and climate variables in mountainous catchments in Central Europe. The period 1966–2012 was used to assess trends in climate and streamflow characteristics using a modified Mann–Kendall test. Droughts were classified into nine classes according to key snow a...

This is the abstract related to the presentation originally prepared for the physical form of the General Assembly of the European Geosciences Union that was to be held in Vienna, Austria in May 2020. We continued the investigation of the influence of snowpack variability on spring and summer low flows/deficit volumes in 59 selected mountain catchm...

The streamflow seasonality in mountain catchments is largely influenced by snow. However, a shift from snowfall to rain is expected in the future. Consequently, a decrease in snow storage and earlier snowmelt is predicted, which will cause changes in spring and summer runoff. The objectives of this study were to quantify 1) how inter-annual variati...

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrol...

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere¹. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe². Any changes in river floods would have lasting implications for th...

In fact, this is an abstract related to the oral presentation that took place during the EGU2019 General Assembly. Basically, it is a continuation of the research into the rain-on-snow (ROS) processes occurring in 15 river basins in selected mountain ranges located in Czechia. Over 110 ROS events were derived based on hourly meteorological and hydr...

In fact, this is an abstract related to the poster presentation exhibited during the EGU2019 General Assembly. Using the HBV (i.e. HBV-light) model and various hydrometeorological time series representing 60 selected mountain catchments from Czechia and the period 1980-2014, it was found that, besides summer precipitation, the previous snowpack has...

The main scope of this study was to present the possibility of developing a heavy rainfall regional model, based on a probabilistic approach. Following the methods and conclusions of the scientific and technical work of the research team in the Upper and Middle Oder basin, carried out on rainfall data between 1961 and 2010, it was found that the ge...

We present the analysis of rain-snow-events hydrological response during the period of 2004 -2014. This analysis is focused on two highest mountain ranges in the Czech Republic - Krkonoše and Jeseníky.

Quite recently, freely available mean daily discharge series representing the territory of Czechia were complemented by ten daily series of nine climate variables, spanning usually from 1961 to the present. Their length thus allows the analyses similar to those conducted approximately a year ago in relation to the long series of discharge. Besides...

The effects of possible climate change on water resources in prescribed areas (e.g. river basins) are intensively studied in hydrology. These resources are highly dependent on precipitation totals. When focusing on long-term changes in climate variables, one has to rely on station measurements. However, hydrologists need the information on spatial...

Systematic records on flowing water temperature in the Czech part of the Danube River basin started in the late 19th century. However, their detailed analyses have been - even after dozens of years with operating monitoring network - performed very rarely. The aim of the present contribution is therefore to bridge this gap at least partially, and t...

This is the final version of the presentation prepared just before showing our main results on 26 September 2017 at the conference venue. The equations presented here slightly differ from those originally published in the conference paper. This is due to the absence of the peer-review process.

Supplementary Information

In fact, this is an abstract related to the contribution that was presented during the workshop of the IAHS Commission on Statistical Hydrology held in Warsaw, Poland in September 2017. Discharge time series recorded in daily time step at nine water-gauging stations installed in selected small river basins in Czechia (having a median catchment size...

This is the oral presentation related to the abstract.

Background: Melissococcus plutonius is an entomopathogenic bacterium that causes European foulbrood (EFB), a honeybee (Apis mellifera L.) disease that necessitates quarantine in some countries. In Czechia, positive evidence of EFB was absent for almost 40 years, until an outbreak in the Krkonose Mountains National Park in 2015. This occurrence of E...

A warming climate is expected to have an impact on the magnitude and timing of river floods; however, no consistent large-scale climate change signal in observed flood magnitudes has been identified so far. We analyzed the timing of river floods in Europe over the past five decades, using a pan-European database from 4262 observational hydrometric...

Honeybee (Apis mellifera L.) workers act as passive vectors of Paenibacillus larvae spores, which cause the quarantine disease American foulbrood (AFB). We assessed the relative proportions of P. larvae within the honeybee microbiome using metabarcoding analysis of the 16S rRNA gene. The microbiome was analyzed in workers outside of the AFB zone (c...

Most hydrometeorological data from Czechia are still provided for a fee. This especially applies to time series with a finer step than monthly. The fact that the data must be paid with respect to an expert's appraisement and that the proper licence agreement ratification has to be performed causes a considerable delay in the data transfer to potent...

In fact, this is an abstract related to the poster presentation exhibited during the EGU2017 General Assembly. It was thought of as a staring point of a new bilateral project (just before submission of its draft) involving Japan and Czechia. The main purpose of this project is the flood risk reduction using different remote sensing products (satell...

Tyrophagus putrescentiae is inhabited by bacteria that differ among mite populations (strains) and diets. Here, we investigated how the microbiome and fitness of T. putrescentiae are altered by dietary perturbations and mite populations. Four T. putrescentiae populations, referred to as dog, Koppert, laboratory, and Phillips, underwent a perturbati...

The honey bee, Apis mellifera, is a globally important species that suffers from a variety of pathogens and parasites. These parasites and pathogens may have sublethal effects on their bee hosts via an array of mechanisms, including through a change in symbiotic bacterial taxa. Our aim was to assess the influence of four globally widespread parasit...

Note that this is PeerJ Preprint and see the FULLTEXT of the final publication https://peerj.com/articles/3816/ Worker honeybees (Apis mellifera) transmit Melissococcus plutonius between colonies. However, the transmission of M. plutonius, which causes European foulbrood (EFB), is poorly understood. To analyze the first EFB outbreak in 40 years i...

This is and excerpt from the book of abstract relating to this conference of statistical hydrologists. The abstract itself relates to the poster presentation exhibited there. Several things should be added here: (1) overall, the GED distribution do not perform so bad and it competes well against the GEV distribution as regards the peak discharge va...

The ectoparasitic mite Varroa destructor is a major pest of the honeybee Apis mellifera. In a previous study, bacteria were found in the guts of mites collected from winter beehive debris and were identified using Sanger sequencing of their 16S rRNA genes. In this study, community comparison and diversity analyses were performed to examine the micr...

The scope of this study was to assess the usefulness of top probability distributions to describe maximum rainfall data in the Lusatian Neisse River basin, based on eight IMWM-NRI meteorological stations. The research material was composed of 50-year precipitation series of daily totals from 1961 to 2010. Misssing measurement data were estimated us...

This is the abstract related to the poster presentation exhibited 18 April 2016 during the General Assembly of the European Geosciences Union. Traditional methods aimed at the derivation of N-year discharges in Czechia by the Czech Hydrometeorological Institute were presented. In addition, results given by the newly developed Extremity Index (EI) u...

This is the poster presentation related to the abstract published during the European Geosciences Union 2016 General Assembly.

In fact, this is the abstract related to the poster presentation exhibited during this conference. Certainly, there is a need for more information on the methodology used. First, the discrimination between STP and LTP (similar to searching for the significance of the Hurst exponent) was based merely on the unit root tests because the combination of...

The poster presentation itself.

Under the proper consideration of climate change one cannot rely on the stationarity of the series fed to a hydrological model. Modelling should rather be based on the assumption of nonstationarity with appropriate discrimination between deterministic and stochastic trends in the series. Although some works regarding the identification of trends in...

This is a corrigendum related to the recently published article on the detection of trends in 7-day low flows in Czechia (doi 10.5194/piahs-369-87-2015). Some of the values in Tables 1 and 2 were corrected.

Trend analysis is a frequently used tool in hydrology and climatology for the identification of long-term changes. However, studies are usually only oriented on local trends. This paper rather focuses on the spatial application of trend analysis in groundwater data. For this purpose, a modification of the Mann-Kendall test was developed, based on t...

Although a nationwide study focusing on the evolution of low flows in Czechia was conducted in the past, a need for the revision of the results has arisen. By means of the trend analysis, which specifically considers the presence of significant serial correlation at the first lag, the former study highlighted areas where 7-day low flows increase or...

The current work addresses one of the key building blocks towards an improved understanding of flood processes and associated changes in flood characteristics and regimes in Europe: the development of a comprehensive, extensive European flood database. The presented work results from ongoing cross-border research collaborations initiated with data...

This is a two-page extended abstract incorporated in one of the successors of IAHS Red Books, now called the Proceedings of the International Association of Hydrological Sciences (PIAHS). The abstract itself relates to a poster presentation exhibited during the 11th Kovacs Colloquium held in Paris, France in June 2014 (hence no figures are present)...

This is the extended abstract related to the poster presentation exhibited during the 6th EGU Leonardo Conference held in Prague in November 2014. Unlike the original version presented in the book of abstracts (available e.g. at http://www.eguleonardo2014.com/abstracts/), this text was improved. Also, the numbers of long memory processes or unit ro...

This is an excerpt from the poster proceedings published on a USB flash drive accompanying material in the IAHS Red Book related to the 7th Global FRIEND-Water Conference. The extended abstract informs about the features of the nonparametric Cox-Stuart test when the series investigated are serially dependent. By means of Monte Carlo simulations, it...

Once a trend is detected in hydrological time series, its generating process should be considered as nonstationary. However, there is a need to discriminate between deterministic and stochastic kinds of trends. Unlike deterministic trends the stochastic trends may be eliminated by differencing. Resulting process may then be pronounced (difference)...

The main aim of this work is to evaluate the development of rainfall-runoff regime in selected river basins of the Šumava Mountains (Bohemian Forest), the Jeseníky Mountains and the Krušné Mountains (Ore Mountains) in the last 50 years. Besides the identification of inhomogeneity in time series of mean discharges, rainfall amounts, temperature and...

The research discusses the analysis of trends of essential hydrometeorological elements using selected statistical methods. The main aim of our research project was to compare the time series of flows with an adequate series of rainfall values; air temperatures and snow cover depths, and thereby try to determine what kind of changes occur in low mo...

Since 2008 Czech Hydrometeorological Institute (CHMI) and T. G. Masaryk Water Research Institute (WRI) have cooperated in study of hydrological drought in the Czech Republic (CR). In 2008 the background research was done and suitable daily streamflow time series from several gauging stations were chosen for detailed analysis. Since the first half o...