VTEI / Hydraulics, hydrology and hydrogeology

Hydraulics, hydrology and hydrogeology

Development of pond locations in the Polabí lowland since the mid-19th century – part 1 – Pardubice region

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This article focuses on mapping the development of the lowland landscape over the last 180 years, related to pressures to use lowland areas for economic purposes, including transformation of wetland habitats (specifically ponds) into arable land.  The Polabí lowland was chosen as the study area because it is currently affected by a lack of water and there is an occurrence of seasonal drying up of small watercourses. This issue will probably be of greater significance in the future, particularly in the context of the expected continued extreme climatic phenomena. Within the Polabí lowland, the results from the Pardubice region (where the biggest change in pond locations occur) are presented here. The area of all types of ponds (according to their stability) makes up 6.83 % of the study area. According to their occurrence from the Second Military Mapping (1836–1852) up to 2022, the ponds were divided into disappeared, continuous, and new. Disappeared ponds have the largest representation – about two-thirds of the total pond area according to stability. They are followed by continuous ponds, and the smallest area is represented by new ponds. The historical, or more precisely, disappeared ponds were more robust than the present ones, i.e., they had a larger average size. Analyses show that almost half of the disappeared ponds have been replaced by arable land.

Optimization network model of water management systems

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The paper describes software aimed at analysing water management infrastructure and identifying critical points for water supply and assessing possible measures aimed at optimising the water supply function of the water management system. The computational procedures integrate the evaluation of the hydrological characteristics of the area, the parameters of the water management and water supply systems and the water supply requirements. The solution uses graph theory and network flow optimization (out-of-kilter algorithm is applied). The program is implemented as a PC application and equipped with a user interface.

Technical Heritage of the Elbe-Vltava Waterway

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From 8th November 2022 to 31st January 2023, an exhibition entitled “Technical Heritage of the Elbe-Vltava Waterway” took place in the atrium of the Faculty of Civil Engineering of the Czech Technical University in Prague (CTU). The exhibition included exhibition panels, an interactive model of a weir lock, a video projection screen, and a stand with a web application www.lvvc.cz. The exhibition mapped the history and development of this 324 km waterway since the beginning of the 19th century, and it is expected to continue as a travelling exhibition.

Landscape changes in selected locations of the Polabí lowlands with a focus on wetlands

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This article presents three typologically different sites from Polabí where large-scale wetland sites were located in the past, including ponds. These sites were chosen in order to present disappeared floodplain meadows, disappeared “field” wetlands, disappeared ponds or pond systems, and, simultaneously, to present sites where wetland habitats have been at least partially restored. The main aim was to present easily accessible archival maps, on the basis of which it is possible to assess the spatio-temporal dynamics of wetland habitats in the places of disappeared wetlands with regard to their possible restoration.

Multi-Criteria Analysis of the Dyje basin

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This article deals with applications of the specific method of multicriteria analysis (MCA) and its use in the identification of areas within the Czech Republic where adaptation measures to the consequences of climate change would be most effective. MCA was chosen due to its comprehensive approach and the simplicity of working with available data in the Czech Republic. The first MCA have already been applied in the Pilsen and Pardubice Regions within the framework of the creation of the strategic document Regional Strategy of Adaptation Measures (Regionální strategie adaptačních opatření, ReSAO), whose aim was to assess the vulnerability of the entire area of these regions. The results from both strategies are expedient from the point of view of drafting adaptation measures, and it was therefore decided to use MCA as part of a larger project in the Dyje basin. In the first phase, the implemented analyses were evaluated to improve MCA for the studied area. In the second phase, MCA was applied to the area of agricultural land. Several thematic indicators were evaluated, namely surface drainage, land use, erosion risk, and occurrence of erosion events. The aim was to focus on IV order basins, in which the priority of implementing measures on agricultural land is the highest. The result was a list of IV order basins with a partial and summary assessment of problems within the total studied area of the Dyje basin.

Agroforestry and its effect on the complex of hydropedological properties of the soil

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The aim of this article is to evaluate landscape retention capacity based on the use of soil protection technology at the chosen site and to compare selected hydropedological characteristics in the context of land management. Therefore, broken and intact soil samples are taken regularly and laboratory analyses are carried out. The chosen site is located in the Šardice cadastral area, Hodonín district, South Moravian region. At the chosen site it is possible to consider grass strips with one or more rows of trees as a possible agroforestry system, where temperature and humidity are measured continuously by TOMST TMS-4 moisture sensors. The results show that the way land is used and cultivated has an impact on hydropedological properties of the land. We can influence them both positively and negatively.

Planned restoration of aquatic ecosystems in Prague 4

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Prague 4 district in accordance with the National Action Plan for Adaptation to Climate Change [1], Concept for Protection from the Effects of Drought of the Czech Republic [2], Strategy for Adaptation of the Capital City of Prague to Climate Change [3] and Methodology for Rainwater Management in the City [4, 5], similarly to other progressive-minded parts of Prague, is preparing investment actions to support and strengthen green-blue infrastructure in the city. One of the most visible measures with truly demonstrable effects on the support of biodiversity and water retention in the landscape is the restoration of aquatic ecosystems. In the case of the capital city of Prague and its most populous district of Prague 4, these are mainly the restoration of canalized (straightened or piped) streams, or desilting, strengthening or comprehensive restoration of ponds and small water reservoirs in a highly urbanized landscape. A specific area is newly emerging bodies of water in places where water naturally tends to be retained after longer periods of rainfall and the area thus cannot be used for any other purpose, or even in places where there was no body of water before (although here in the narrower sense of the word it is not restoration). For such areas created by human intervention in order to strengthen the diversity of aquatic and wetland vegetation, the name artificial aquatic biotope has been adopted. Let us have a look at the differences and specific pitfalls of individual restoration using three specific examples.

Historic floods on Rakovnický stream

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This year, TGM WRI is planning to publish a book by Kašpárek, Elleder, Šírová, Dragoun, and Kašpárek Jr., dedicated to floods in the Rakovnický stream basin. It is primarily focused on the occurrence of floods before the start of instrumental observation, that is before 1898. Its purpose is to maximally expand knowledge about the frequency, seasonality, and most significant flood cases, their causes, extent, impact, and damage over the last 500 years.

Radioactive indicators in surface waters of the Ploučnice river basin

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The Czech Hydrometeorological Institute (CHMI) is engaged in systematic monitoring and evaluation of radiological indicators in surface waters. The article describes changes in the values of radiological indicators in surface waters in the time series from 1967 to the present. The evolution of total volume alpha and beta activity, uranium concentration, and radium activity (226Ra) is described on characteristic profiles in the area of uranium-containing raw materials mining, in the vicinity of Stráž pod Ralskem, where the mining of radioactive raw materials has already been suppressed. The Ploučnice river flows through this mining area and flows into the Elbe river in Děčín near the Hřensko border crossing, where activities of radiological indicators are also monitored and documented. Following the cessation of uranium mining at the Stráž pod Ralskem deposit, uranium concentrations dropped by two orders of magnitude, and surface waters on the Ploučnice – Mimoň profile have been classified as Class I – unpolluted water for the last five years. The values of Kendall’s correlation coefficient τ for the profiles evaluated on the selected profiles during the mining period are characterized by an increasing trend (+0.7) for the indicator of total volume beta activity; after the end of mining, a decreasing trend is indicated (-0.5).

Impact of weir construction at locality Abovce (Slovakia) on groundwater levels – a case study from Slaná river basin

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The construction of weirs on rivers affects the dynamics of groundwater levels. The weir built on the river Slaná in the year 2010 between the village of Abovce and Chanava brought the opportunity to study such impact due to preexisting groundwater monitoring wells of the Slovak Hydrometeorological Institute. to verify the impact of the constructed weir on groundwater dynamics in the area, records of weekly data were used ranging from 1986 to 2018. In addition, the spatial range of influenced areas was carried out using geographical information systems, and spatial interpolation techniques were used. The results showed that immediately after the construction of the weir, the groundwater level rose significantly.

Potential of areas protected for surface water storage to mitigate the impacts of climate change on drinking water supply

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In the Czech Republic, areas morphologically, geologically and hydrologically suitable for surface water storage to mitigate the adverse effects of floods and droughts are defined through the General Plan for Surface Water Accu-mulation Areas. In the context of climate change, these locations create potential for possible adaptation measures. This article describes the assessment of the potential of selected sites for water supply under climate change condi-tions by means of hydrological and water balance modelling.

Small headwater catchments – spatial delimitation and their classification in terms of runoff risks

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This article presents an aerial delineation of small headwater catchments up to 5 km2 in the Czech Republic. The aim was not only to present the delineation of these catchments, but also their categorization in terms of the characteristics affecting the formation of direct runoff. Direct runoff caused by torrential rainfall is a very dynamic process of episodic nature and has a major impact specifically in small catchments. The delineation of small headwater catchments, where the aforementioned processes take place, can complement the standard hierarchical classification of basins in the Czech Republic. These basins make up 80 % of the Czech Republic.

Modelling flow distribution in inlet galleries

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The main objective of the article was to optimize the facilities used to distribute flows in inlet galleries, which are used not only in water treatment plants, but also in wastewater treatment plants (WWTP). While working in the field of WWTP, it was found that there are no optimized facilities in the Czech Republic or globally for uniform distribution of flows to any number of inlet branches into reservoirs of the same flow rate.  Currently, in most unregulated facilities, there are significant differences between the various inlet branches to the reservoirs. In regulated facilities, the outlets must be regulated at each change in flow rate and, for changes in the number of inlets to the reservoir (e.g., due to reservoir shutdown), each outlet must be manually adjusted (e.g., using a sluice gate) so that all inlets to reservoirs have the same flow rate. In more modern cases, the sluice is equipped with an electric motor for changing the position and a probe sensing the level. The central unit then calculates the flow rate in the individual reservoir inlets and adjusts the position of the sluice gates so that the same flow rate is achieved everywhere. The objective of the research was to optimize the distribution facility so that the inlets to the reservoirs reach similar values for the flow rate when both the inflow to the distribution facility and the number of inlet branches to the reservoirs are changed, without significant regulation at the distribution facility. In order to make the research easily applicable to as many distribution facility as possible, the most commonly used flow distribution facilities (fountain spillway, flume with outlets fitted with a sluice gate and probe for level monitoring, etc.) were selected to address the issue. Different flow conditions were simulated on the selected facilities (in different variants and shapes); after their analysis the facilities were optimized in order to achieve the most similar flows at the inlets to the individual reservoirs.

Interview with Jaroslav Pollert, professor at the Faculty of Civil Engineering at CTU and a successful Czechoslovak representative in canoeing

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An interview with Jaroslav Pollert, professor of the Faculty of Civil Engineering at CTU and a successful Czechoslovak representative in canoeing, about his work as part of the Executive Committee of the International Canoeing Federation (ICF), the Czechoslovak and later the Czech Olympic Committee, about his professional career focused on the hydrodynamics of dispersion systems including, among other things, designing channels for water slalom and about his view on water management studies at Czech universities.

Irrigation – rediscovered heritage, its documentation, popularisation and protection based on the example of historical meadow irrigation systems

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Objekty závlah byly budovány a fungují převážně jako součást většího nebo menšího funkčního celku. Jejich význam i z pohledu potenciální pa-mátkové ochrany tak roste s identifikací a dokumentací nejen solitérních staveb, ale zejména celých soustav/funkčních celků a popisem vazeb mezi nimi. Samostatný objekt či stavba nemusejí být nijak výjimečné, avšak jejich zapojení do většího funkčního celku může vytvářet unikátně pojaté řešení. V oboru vodního hospodářství se obzvlášť projevuje důležitost a význam kritérií, jako je hodnota typologická, hodnota technologického toku, autenticita formy a funkce, hodnota technologických a systémových vazeb s přesahem do zemědělství či průmyslu. Článek přináší informace o možnostech využití tradičních metod historického a archivního výzkumu a dokumentace lokalit, jakož i o využití moderních nástrojů pro plošně rozsáhlejší systémy, včetně metod digitalizace a digitálního zpracování podkladů.

The construction of large hydraulic structures in the context of ideas and ideologies

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This paper deals with some aspects of the relationship between man and water demonstrated via the example of large hydraulic structures constructed in the Czech lands. Based on this relationship, principles of the practical functioning of ideas and ideologies, including religion, can be presented. It is not just about “pagan” cults, aiming directly at worshipping water as a living being. Christianity also significantly influenced the framework in which water management operated across the centuries and, at the same time, new ideas associated with the Enlightenment and the Industrial Revolution during the 18th and 19th centuries. A key part of the paper is focused on the topic of the construction of large hydraulic structures in the 20th century, which was particularly intensive in its second half. It also mentions political, ideological, and natural changes which were, at the beginning of the 21st century, reflected in man’s relationship with water resources and the possibilities of influencing them.

Banská Štiavnica water management system – an important UNESCO technical monument

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From the 16th to the 19th century, a unique water management system was created in Banská Štiavnica and its vicinity, which served the local mines. The water management system consisted of water channels – collecting ditches, which concentrated surface water from Štiavnické vrchy (Štiavnica mountains) and brought it to the mining water reservoirs (tajchy). Tajchy are water reservoirs that were built to accumulate surface water from the collecting ditches. Water from the tajchy was discharged into water canals – transporting ditches that brought water to the shafts. Here, the water was piped into the depths of the mine, where the obtained water energy powered pumping machines that pumped groundwater out of the flooded mines. Once the groundwater was drained, the miners could continue extracting gold and silver. Water-powered processing facilities also operated in Banská Štiavnica and its vicinity, which processed the extracted
ore from the mines. For centuries, the Banská Štiavnica water management system set in motion more than a hundred water-powered devices. The system consisted of about 60 tajchy, 170 km of ditches, and 15 water tunnels.

Estimation of natural groundwater resources in hydrogeological zones in the Czech Republic under changing climatic conditions 1981–2019

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In the Czech Republic, hydrogeological zones were defined as early as 1965 as a part of the regional hydrogeological survey. A hydrogeological zone (HGZ) is defined as a unit with similar hydrogeological conditions, defined tectonically and geologically, in whose territory a certain type of aquifer and groundwater circulation prevails. The boundaries of HGZs have been modified over time and their numerical hydrogeological characteristics have been determined by various methods; one of the basic characteristics is the amount of natural groundwater resources. Natural resources are the dynamic component of groundwater and are expressed in m3.s-1. They are determined by the recharge of water to the aquifer system (precipitation, groundwater overflows from other aquifers, natural infiltration of surface water, etc.). If the HGZ is hydrogeologically closed, the long-term average of its recharge from precipitation and the long-term average of baseflow can be used as an estimate of the natural groundwater resource. In the “Groundwater Rebalance Project”, estimates of natural groundwater resources in 152 hydrogeological zones in the Czech Republic were processed and are presented in the report [1]. The natural resources were determined by several different methods using data from 1971–2010 and 2000–2010. 

Impact of Teplice restoration on river basin runoff – preliminary results

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As part of the project for the Ministry of the Environment of the Czech Republic dealing with the monitoring of the impact of nature­‑friendly measures on improving the hydrological regime of small river basins, the Teplice river basin in the White Carpathians has been observed. Monitoring has been taking place since 2018, the measures were implemented in 2020. Data are available for the time period before the measures were implemented and for the year 2021, on which it is possible to observe the impact of the implemented revitalization. The data show the fluctuation of the daily runoff from the river basin and its overall reduction, which is probably caused by increased evaporation from the newly formed water bodies and increased water infiltration into the underground zone. After evaluating the observed data, there was a visible reduction in the surface runoff from the basin, which may nevertheless also be caused by the low rainfall totals in 2021.

Measuring annual precipitation with a radar rain gauge in severe mountain conditions

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The aim of this article is to describe the experience gained while using alternative technology for measuring annual precipitation in severe mountain conditions without a source of electrical energy. For this purpose, a Lufft WS100 radar precipitation sensor was installed in Šumava in 2020 at an altitude of 1270 m above sea level. The measurements so far have shown evident advantages; for example, maintenance free sensor, detailed measurement step, and distinction of the type of precipitation. The question remains how accurate the measurement is, when during some precipitation episodes the radar precipitation sensor probably overestimates its measurements. Accurate comparison with other measurements is difficult in these mountain ridge conditions. On the other hand, the radar sensor also gives accurate measurements during some precipitation episodes, which we verify by a non-heated tipping bucket rain gauge located within the station and also by measuring the height of the snow. Using these proxy data, systematic error was excluded. Measurements will continue for a more detailed evaluation. The radar sensor is, among other things, part of the monitoring of Kaplický potok in Boubín National Nature Reserve, where runoff is also monitored. From this point of view, information about precipitation and its type is important for the evaluation of the hydrological properties of the basin.  

The current version of the BILAN model

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BILAN je celistvý konceptuální model v denní/měsíční struktuře (schéma je uvedeno na obr. 1), simulující složky hydrologické bilance na povodí. Přestože jeho vývoj byl nastartován ve VÚV TGM již počátkem devadesátých let minulého století, jde o model, který je v České republice stále standardně používán a zůstává přístupný laické i odborné veřejnosti. Například je nedílnou součástí řešení aplikace/systému HAMR [1], ale byl použit i jinde [2–4]. Mezi hlavní výhody modelu oproti jiným řešením patří interní kalibrační algoritmy, možnost přímého vkládání dat o užívání vod a nízká výpočetní náročnost vhodná pro variantní simulování (např. dopadů klimatické změny na vodní režim).

Annotation of the exhibition Irrigation – rediscovered heritage, its documentation and popularization

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As a response to landscape drainage in the modern era, caused by the intensification of agriculture, the drying up of ponds, and land reclamation activities, interest in the opposite process has reappeared, i.e. irrigation. Existing irrigation systems, at present often non-functional and preserved only in parts, have become the subject of interest for this project which tried to capture the historical development of this specific water management field as well as part of the industry associated with the implementation of irrigation and the production of soil irrigation equipment.

Centrum Voda (Center Water)

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Centrum Voda je výzkumný projekt, který hledá řešení problémů vyplývajících z klimatické změny a jejího vlivu na vodní poměry. Snažíme se nalézat odpovědi na základní otázky, jestli dokážeme zajistit dostatek kvalitní vody nejen pro potřeby člověka, ale i pro naši krajinu, zda se zvládneme vyrovnat s přívalovými povodněmi a jak dále snižovat znečištění vodního prostředí.

Extreme multi-annual hydrological droughts in the Elbe river basin

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The aim of the study was the evaluation of multi-year hydrological droughts in the Elbe river basin for the Děčín stream gauging station (catchment area 51 104 m2). Average monthly flows from period 1851–2000 are available for the station. For this period, we also compiled a series of average monthly precipitation and temperatures from several data sources. We calculated annual values for precipitation, temperatures and differences in annual precipitation and runoff, then we computed long-term averages and regression linear trends for change over time. The trends are only slightly upward for all three variables, but long-term fluctuations in precipitation are more significant. According to the quantified multi-year average flows and precipitation, we searched for and merged cases from which one continuous drought lasting at least 5 years is generated for both precipitation and runoff. We quantified deficit volumes for individual drought periods. The long-term average flow was chosen as the threshold flow. The hydrological drought 2013–2020 had the longest duration, almost 7 years, of all droughts since 1851 and was also characterized by the largest total deficit volume. When compared to the average annual deficit volume, it is only in fourth place. When comparing the time series of monthly flows, it turned out that cases from different periods have similar patterns and behavior.

The influence of Prague on water quality in the Vltava and the Czech Elbe

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Paper deals with the development of water quality of the river stretch of Elbe between the confluence Elbe/Vltava and the Hřensko/Schmilka on the frontier Czech Republic/Federal Republic of Germany in the period 1980–2020 and with the influence of Prague City on its pollution. After the significant improvement in the period 1985–2000, the quality of water discharged through the profile Hřensko generally complies with the German level at least. Assessment of the transport budgets shows that Vltava river contributes more to the system only as having higher water discharges. Prague City contributes to the pollution of Vltava and Elbe only by discharge of phosphorus, for the rest of common pollution items it functions only as a non-significant source.

Impact of climate change on runoff and development of forest composition in the coming decades in a selected river basin in Slovakia

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Climate change is a global phenomenon that affects changes in forest composition. Therefore, the article deals with changes in forest associations as a result of global climate changes. The aim of the research was estimation of change in forest associations under climate change on the runoff processes in the selected river basin. We used two land use scenarios with forest associations and two global climate change scenarios. Land use scenarios were created for the entire territory of the Slovak Republic by the Technical University of Zvolen. The outputs of the KNMI and MPI regional climate change models (both with A1B emission scenario) were used for this research. As a result of climate change, changes in forest composition can be expected.

The Výrovka river basin as a suitable area for monitoring and comparing hydrological and landscape characteristics

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The Výrovka river basin, as a compact area covering 542.5 km2, is very suitable for monitoring hydrological characteristics and comparing them in different landscape types. It is located on the border of the Lower Vltava and Upper and Middle Elbe sub-basins, extending in a range of 175–555 m above sea level, with a total of six landscape types according to the typology of the contemporary landscape of the Czech Republic. Simultane-ously, there is a varied mosaic in terms of geological subsoil and soil types. There have also been major changes in land use in this basin, mainly due to intensive agricultural activity and related watercourse modifications and amelioration. Monitoring activities within the project SS02030027 ”Water systems and water management in the Czech Republic in conditions of climate change” are currently taking place in the Výrovka river basin.

Use of SARS-CoV-2 virus monitoring in wastewater from WWTP of various categories for epidemic surveillance in the Czech Republic

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The principle of wastewater diagnostics is a suitable complementary approach that can help to gain epidemiological information on a large part of the population in a non-invasive way. The course of the pandemic spread of the new coronavirus (SARS-CoV-2) has been showing a cyclical course of successive waves of Covid-19 since 2020. For this model, a systematic detection of the occurrence of its agent in wastewater is a very effective approach.

Detection of gully erosion using the method of Global Navigation Satellite Systems in the Myjava – Turá Lúka

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This paper shows the partial outcomes of a study focused on monitoring gully erosion in the Myjava river basin. The study showed the progress of dynamic changes in gully erosion in the location of Turá Lúka using various surveying techniques from 2014 until present. The study shows that selection of the surveying technique depends on various criteria and the aims of the task, where each possesses advantages and disadvantages. In the case of determination of the parameters of gully erosion (volume, length, and position), one of the suitable surveying techniques is Terrestrial Laser Scanning (TLS) as well as Unmanned Aerial Vehicles (UAV), which results in a point cloud. Measurement using Global Navigation Satellite Systems (GNSS) with a GPS device is sufficient for assessing gully erosion in transverse profiles, more complex sections, or in places with built anti-erosion and stabilization dams in a gully. This assumption was confirmed based on results from field measurements of an erosion gully by GNSS technology in 2017–2021. Evaluation of the results is given in this article. The given method of mapping the erosion gully was chosen for the need for detailed profile evaluation of previously identified critical sections (transverse profiles) of the monitored erosion form based on field surveying and area scanning and for simple data processing. The simplicity of this method due to the type of task, staffing, time, and volume of data predetermines and confirms the suitability of its selection for use under the given circumstances. When choosing this measuring technique, the requirements are easy access to the measuring point and a good satellite signal for GPS devices influencing the accuracy of the measurement concerning the surrounding vegetation. Sufficient testing and comparison of available surveying techniques make it possible to efficiently and realistically select suitable effective technology for monitoring erosive forms in the landscape for a predefined purpose. Contributions of this type will help researchers of similar tasks in decision-making when choosing the most suitable landscape surveying technology.

Changes in precipitation and runoff in river basins in the Czech Republic during the period of intense warming

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The basic meteorological variables that affect the hydrological regime are atmospheric precipitation and air temperature. Both fluctuate not only in the short term and in the annual cycle, but also in the long term. Long-term changes in both of these variables have the character of periodic fluctuations around the mean values. Since about 1980, there has been a systematic increase in air temperature in the Czech Republic. This article provides information on how the climate fluctuations that this change brings affect the precipitation and runoff regime in our territory.

Occurrence of pesticides in the Punkva river

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The Moravian Karst is the largest and most karstic area in the Czech Republic, and, as such, it is a protected landscape area (PLA). The karst area occupies a strip of Devonian limestone north of Brno. The north part of Moravian Karst is drained by the river Punkva and its headwaters. One of the biggest cave systems in central Europe is located there, Amaterska cave, which is more than 40 km long.
Despite the strict protection measures that are in place in the PLA, the presence of pollutants and potentially hazardous substances has recently been detected in the Punkva river and its catchment. The sources of this pollution are found both within the territory of Moravian Karst PLA and in the river´s catchment, and they are related to anthropogenic activities and land use. This article focuses on the occurrence of pesticides, especially triazine and azole pesticides and their polar metabolites. In 2020, a new significant contaminant, 1,2,4-triazole, a common relevant metabolite of azole pesticides, was found at the site concerned. These substances can have fatal effects not only on the endemic organisms living in the Moravian Karst, but they can also endanger human health because the local groundwater is used as a source of drinking water. Thanks to the studies carried out, the protection zones around the cave system have been extended, reducing the negative effects of agricultural activities in the area of interest.

Monitoring changes in the landscape development on the northeastern edge of the Hřebeny Mountains with a focus on wetlands

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This article deals with changes in wetlands on the north-eastern edge of Hřebeny Mountains in the last 180 years. It assesses the dynamics of these landscape elements in space and time. The cadastral areas of Čisovice, Řitka, Kytín, and Nová Ves pod Pleší were selected, with a total area of 3,785.57 ha. Analysis was carried out on the basis of the Imperial obligatory prints of the maps of the stable cadastre from 1840, an orthophotomap, and field research from 2020; it distinguished wetlands in the monitored area into continuous, extinct and new. The background data were processed in ArcGIS software, version 10.7.1. The area of wetlands decreased from 289.34 ha in 1840 (7.6% of the monitored area) to 39.26 ha in 2020 (1.04% of the monitored area). Based on the study of available data, three types of wetland habitats were classified: wet meadows, wet meadows with woody plants, and ponds.

Comparison of hydrological characteristics of M-day discharges of the reference period 1981–2010 and the considered reference period 1991–2020

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According to the Czech technical standard ČSN 75 1400 Hydrological data of surface waters, M-day discharges are a part of the Basic hydrological data [1]. The values of M-day discharges in water gauging stations are derived from time series of observed mean daily discharges over a defined reference period. The reference period 1981–2010 is currently used for design purposes [2]. With the end of the second decade of the 21st century, a change in the reference period for 1991–2020 is being considered. In the past, the Czech Hydrometeorological Institute (CHMI) provided hydrological data for the reference periods 1931–1940, 1931–1960, and 1931–1980.

Zero isochion in the framework of geomorphological regions in Czechia: its extraction from the MODIS imagery and its dynamics

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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 forecasting models to give relevant results. In order to get a better idea about current spatial distribution of snow cover in Czechia, the information on the zero isochion has been extracted from the MODIS imagery coming from the Terra satellite.

Practical examples of using GIS in hydrology at the Czech Hydrometeorological Institute

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GIS technologies are widely used in the Hydrology Department of the Czech Hydrometeorological Institute (CHMI). The processing of geospatial data, which are used in hydrology for analytical tasks, and the development of GIS technologies in the last two decades have contributed to the spread of GIS in the CHMI practice. The use of GIS tools is shown in four examples. The first one focuses on the creation of GIS data. The second example concerns the preparation of input source data for the derivation of the hydrological characteristics of M-day discharge, which, according to Czech Standard 75 1400 Surface water hydrological data, are among the basic hydrological data. The third example describes the use of GIS in the preparation of hydrological assessments according to the above-mentioned standard (75 1400), which usually result in M-day or N-year-flood discharges in a specified profile of a certain watercourse. The fourth example focuses on the use of GIS in operational hydrological service, specifically in the development of the Flash Flood Indicator, which determines the level of risk of flash flood formation or occurrence based on current land saturation and radar rainfall estimates.

Mini-JET device as a tool for determination of soil erodibility characteristics

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The article describes a method for determining the erodibility of incohesive agricultural soils by means of the critical shear stress measuring. The “Jet Erosion Test” (JET) was used to determine the critical shear stress. The mea-
surement was performed using a modified Mini-JET device. The device is very suitable for field measurements, because it is small, light, requires a relatively small amount of water, and can be operated by single person. The principle of measuring the critical shear stress of the soil is based on monitoring the rate of erosion crater formation by the action of a water jet of known kinetic energy. Based on the erosion crater development, the erosion parameters of the soil, such as the critical shear stress and the erodibility coefficient, can be calculated.