Tomáš Vitvar

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Papers by Tomáš Vitvar

Examination of Global River Systems Using Stable Isotope Methods

Stable isotopes (δ2H and δ18O) have been used for many years to understand how precipitation is t... more

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A Comparative Study of Mining Control in Latin America

Mining, 2021

This study analyzes various regulatory framework mechanisms applied to prevent, minimize, and mit... more This study analyzes various regulatory framework mechanisms applied to prevent, minimize, and mitigate environmental accidents and disasters, within the extractive mining industry, in seven Latin American countries. The selected countries offer an ample view of the mining industry specter since each one of them is at the different development stages, such as Chile, Bolivia, Mexico, and Brazil. Nevertheless, some of the countries have similar technical characteristics, as is the case of Peru, Colombia, and Ecuador. Controls and regulations employed in each of the countries reveal particularities that should be appreciated and understood. In conclusion, the existence of mining regulations has not diminished the occurrence of environmental accidents in those countries. However, the existing environmental controls allow authorities to quantify with substantial precision the degree of impact coming from Latin America’s mining industry. Furthermore, for more than a decade, mining industri...

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A Multi-Index Analysis Approach to Heavy Metal Pollution Assessment in River Sediments in the Ponce Enríquez Area, Ecuador

Water, 2019

The area of Ponce Enríquez, Southern Ecuador, is one of the most important artisanal and small sc... more The area of Ponce Enríquez, Southern Ecuador, is one of the most important artisanal and small scale gold mining (ASGM) areas in the country, where informal mining operations can be found using amalgamation technique, even though it has been prohibited since 2010. Considering the potential impact of these mining operations, the present research focused on heavy metal pollutants in subsurface sediments at 214 sampling locations from several detailed sampling campaigns in the rivers Fermín, Fermín Norte, Guanache, Villa, and Siete. Four parameters were calculated to evaluate the geochemical composition of the river sediment and heavy metal concentrations: The enrichment factor (EF), the geo-accumulation index (Igeo), the contamination factor (Cf) and the pollution load index (PLI). The analyzed elements were Cu, Pb, Zn, Ni, As, Cd, Sb, Sr, and Hg. Due to the lack of standards for pollution levels in sediments in Ecuador, Canadian guidelines were used as interim sediment quality guidel...

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Application of geochemical and stable isotopic tracers to investigate groundwater salinity in the Ochi-Narkwa Basin, Ghana

Hydrological Sciences Journal, 2017

Rainwater, groundwater and soil-water samples were analysed to assess groundwater geochemistry an... more Rainwater, groundwater and soil-water samples were analysed to assess groundwater geochemistry and the origin of salinity in the Ochi-Narkwa basin of the Central Region of Ghana. The samples were measured for major ions and stable isotopes (δ 18 O, δ 2 H and δ 13 C). The Cl − content in rainwater decreased with distance from the coast. The major hydrochemical facies were Na-Cl for the shallow groundwaters and Ca-Mg-HCO 3 , Na-Cl and Ca-Mg-Cl-SO 4 for the deep groundwaters. Groundwater salinization is caused largely by halite dissolution and to a minor extent by silicate weathering and seawater intrusion. Stable isotope composition of the groundwaters followed a slope of 3.44, suggesting a mixing line. Chloride profiles in the soil zone revealed the existence of salt crusts, which support halite dissolution in the study area. A conceptual flow model developed to explain the mechanism of salinization showed principal groundwater flow in the NW-SE direction.

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A Tri-National program for estimating the link between snow resources and hydrological droughts

Proceedings of the International Association of Hydrological Sciences, 2015

To evaluate how summer low flows and droughts are affected by the winter snowpack, a Tri-National... more To evaluate how summer low flows and droughts are affected by the winter snowpack, a Tri-National effort will analyse data from three catchments: Alpbach (Prealps, central Switzerland), Gudjaretis-Tskali (Little Caucasus, central Georgia), and Kamenice (Jizera Mountains, northern Czech Republic). Two GIS-based rainfall-runoff models will simulate over 10 years of runoff in streams based on rain and snowfall measurements, and further meteorological variables. The models use information on the geographical settings of the catchments together with knowledge of the hydrological processes of runoff generation from rainfall, looking particularly at the relationship between spring snowmelt and summer droughts. These processes include snow accumulation and melt, evapotranspiration, groundwater recharge in spring that contributes to (the) summer runoff, and will be studied by means of the environmental isotopes 18 O and 2 H. Knowledge about the isotopic composition of the different water sources will allow to identify the flow paths and estimate the residence time of snow meltwater in the subsurface and its contribution to the stream. The application of the models in different nested or neighbouring catchments will explore their potential for further development and allow a better early prediction of low-flow periods in various mountainous zones across Europe. The paper presents the planned activities including a first analysis of already available dataset of environmental isotopes, discharge, snow water equivalent and modelling experiments of the (already) available datasets.

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A Review of Isotope Applications in Catchment Hydrology

Isotopes in the Water Cycle

Swiss prealpine Rietholzbach research catchment and lysimeter: 32 year time series and 2003 drought event

Water Resources Research, 2012

The prealpine Rietholzbach research catchment provides long‐term continuous hydroclimatological m... more The prealpine Rietholzbach research catchment provides long‐term continuous hydroclimatological measurements in northeastern Switzerland, including lysimeter evapotranspiration measurements since 1976, and soil moisture measurements since 1994. We analyze here the monthly data record over 32 years (1976–2007), with a focus on the extreme 2003 European drought. In particular, we assess whether the well‐established hypothesis that the 2003 event was due to spring precipitation deficits is valid at the site. The Rietholzbach measurements are found to be internally consistent and representative for a larger region in Switzerland. Despite the scale discrepancy (3.14 m2 versus 3.31 km2), the lysimeter seepage and catchment‐wide streamflow show similar monthly dynamics. High correlations are further found with other streamflow measurements within the Thur river basin (1750 km2) and—for interannual anomalies—also in most of northern Switzerland. Analyses for 2003 confirm the occurrence of e...

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The response of the water fluxes of the boreal forest region at the Volga's source area to climatic and land-use changes

Physics and Chemistry of the Earth, Parts A/B/C, 2002

The project ''Volgaforest'' was focused on a study of the water budget of the forested Upper Volg... more The project ''Volgaforest'' was focused on a study of the water budget of the forested Upper Volga catchment in Russia in order to describe: • the terrestrial water balance of the Upper Volga catchment as a function of external factors, such as climate and land-use, and • the response of forest ecosystems to these external factors. Future changes of water budget of the Upper Volga catchment area were estimated from: past and present dynamics of the atmospheric, water and forest conditions, different climatic scenarios and SVAT (Soil-Vegetation-Atmosphere Transfer) and hydrological models. Analysis of past climatological and hydrological data showed a large atmospheric and hydrological variability of the Upper Volga catchment. During the last 50-60 years the mean annual air temperature increased by 1.2°C, and annual precipitation increased by 140 mm. However, no significant trend of annual runoff during the last 20 years could be found. Air temperature and precipitation changes were significant during winter and spring but very small in summer. Coniferous and mixed coniferousbroadleaf forests cover at present about 72% of the catchment area. During the last 30 years the area of natural coniferous forests (spruce, pine) decreased from 8.4% to 7% and the area of mixed forests increased from 52% to 59% of the total land area. Results of field measurements at a forest site showed a large variability of energy and water fluxes during the entire year. Transpiration of the boreal forest ecosystem measured using a sap flow method during the dry summer 1999 was limited by very dry soil water conditions, especially for spruce trees, and during the rainy summer 2000 probably by lack of oxygen in the rooting zone. Transpiration was about 10-20% larger for broadleaf trees (birch, aspen) than for spruce trees. Model estimations of possible changes in the hydrological regime of the Upper Volga catchment area for climatic scenarios suggest changes of evapotranspiration, surface runoff and soil moisture storage. Reduced snow accumulation, earlier melting, increased runoff reaction on precipitation in autumn and winter and drier soils in summer are the principal impacts on water resources of predicted future climatic changes. Surface runoff during the spring will be higher but summer and autumn runoff can be slightly suppressed by higher transpiration of deciduous tree species. Decreased summer precipitation and increased transpiration will result in decreasing ground water discharge, and lowering water levels of Volga river and of the Upper Volga lakes.

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Flow pattern and residence time of groundwater within the south-eastern Taoudeni sedimentary basin (Burkina Faso, Mali)

Journal of Hydrology, 2011

Groundwaters with very long residence time up to more than 30 ka were identified within the Taoud... more

Effects of suburban development on runoff generation in the Croton River basin, New York, USA

Journal of Hydrology, 2005

The effects of impervious area, septic leach-field effluent, and a riparian wetland on runoff gen... more The effects of impervious area, septic leach-field effluent, and a riparian wetland on runoff generation were studied in three small (0.38-0.56 km 2) headwater catchments that represent a range of suburban development (high density residential, medium density residential, and undeveloped) within the Croton River basin, 70 km north of New York City. Precipitation, stream discharge, and groundwater levels were monitored at 10-30 min intervals for 1 year, and stream water and groundwater samples were collected biweekly for d 18 O, NO 3 K , and SO 4 2K analysis for more than 2 years during an overlapping period in 2000-2002. Data from 27 storms confirmed that peak magnitudes increased and recession time decreased with increasing development, but lags in peak arrival and peak discharge/mean discharge were greatest in the medium density residential catchment, which contains a wetland in which storm runoff is retained before entering the stream. Baseflow during a dry period from Aug. 2001-Feb. 2002 was greatest in the high-density residential catchment, presumably from the discharge of septic effluent through the shallow groundwater system and into the stream. In contrast, moderate flows during a wet period from Mar.-Aug. 2002 were greatest in the undeveloped catchment, possibly as a result of greater subsurface storage or greater hydraulic conductivity at this site. The mean residence time of baseflow was about 30 weeks at all three catchments, indicating that human influence was insufficient to greatly affect the groundwater recharge and discharge properties that determine catchment residence time. These results suggest that while suburban development and its associated impervious surfaces and storm drains accelerate the transport of storm runoff into streams, the combined effects of remnant natural landscape features such as wetlands and human alterations such as deep groundwater supply and septic systems can change the expected effects of human development on storm runoff and groundwater recharge.

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Estimation of baseflow residence times in watersheds from the runoff hydrograph recession: method and application in the Neversink watershed, Catskill Mountains, New York

Hydrological Processes, 2002

A method for estimation of mean baseflow residence time in watersheds from hydrograph runoff rece... more A method for estimation of mean baseflow residence time in watersheds from hydrograph runoff recession characteristics was developed. Runoff recession characteristics were computed for the period 1993–96 in the 2 km2 Winnisook watershed, Catskill Mountains, southeastern New York, and were used to derive mean values of subsurface hydraulic conductivity and the storage coefficient. These values were then used to estimate the mean baseflow residence time from an expression of the soil contact time, based on watershed soil and topographic characteristics. For comparison, mean baseflow residence times were calculated for the same period of time through the traditional convolution integral approach, which relates rainfall δ18O to δ18O values in streamflow. Our computed mean baseflow residence time was 9 months by both methods. These results indicate that baseflow residence time can be calculated accurately using recession analysis, and the method is less expensive than using environmental...

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A comparative study in modelling runoff and its components in two mountainous catchments

Hydrological Processes, 2003

In mountainous catchments the quality of runoff modelling depends strongly on the assessment of t... more In mountainous catchments the quality of runoff modelling depends strongly on the assessment of the spatial differences in the generation of the various runoff components and of the flow paths as coupled with the amount and intensity of precipitation and/or the snow melting. These catchments are also suitable for the intercomparison of different kinds of hydrological models, particularly of different approaches for the simulation of runoff generation. Two differently structured catchment models were applied on the pre‐alpine Rietholzbach research catchment (3·2 km2) within the period 1981–98 and on the high‐alpine Dischmabach catchment (43 km2) within the period 1981–96 for the simulation of hydrological processes and of the runoff hydrographs. The models adopted are the more physically based WaSiM‐ETH model, with grid‐oriented computation of the water balance elements, and the rather conceptual PREVAH model, based on hydrological response units. The simulation results and the diffe...

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Long-term tritium monitoring to study river basin dynamics: case of the Danube River basin

Better characterization of young and old groundwater systems through improved groundwater dating by isotope methods

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Water residence times and runoff generation in a small prealpine catchment (Rietholzbach, Northeastern Switzerland)

A concept of groundwater residence time distributions and flowpaths in the prealpine catchment Ri... more A concept of groundwater residence time distributions and flowpaths in the prealpine catchment Rietholzbach in northeastern Switzerland has been developed. The catchment covers an area of 3.18 km2 and ranges from 680 to 950 m a.s.l. It is part of the Upper Freshwater Molasse overlaid by Quaternary deposits. The work was based on the use of environmental tracers and is divided into two basic parts. The first one focusses on the estimation of mean residence times and the second one treats the determination of source areas and flowpaths. In the first part the mean water residence times were estimated by means of inverse lumped-parameter simulations of 180 output functions under quasi steady-state conditions between January, 1994 and June, 1996. Comprehensive measurements of 180 content in precipitation and at various outlet sites were carried out. The dating of the oldest groundwater component was carried out using 85Kr. New approaches for parametrization of the l80 input function were...

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Hydrochemical and Isotopic Tracing of Runoff Generation in the Small Mountainous Catchment Uhlířská (Czech Republic), Using the Netpath Approach

A hydrological and hydrochemical-isotopic analysis was conducted in soilsurfaceand groundwater co... more A hydrological and hydrochemical-isotopic analysis was conducted in soilsurfaceand groundwater compartments of the crystalline Uhlirska headwater catchment (1.78 km) located in the Jizera Mountains in the northern Czech Republic. Three scenarios of the inverse geochemical modeling tool NETPATH were examined to trace the chemical evolution and separate the proportions of the soil and groundwater components. About 2/3 of the streamflow can be accounted to baseflow supplied by wetland Histosol peatwater with an admixture of more (about 10 m) or less (about 5 m) deep groundwater. About 1/3 of streamflow is accounted to direct components, originating in the hillslope Cambisols and in the direct rainfall. The results are inline with separation of runoff components using conventional hydrological approach and allow to determine the geoochemical origin of the components.

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Large scale manipulation of the interactions between key ecosystem processes at multiple scales: why and how the falcon array of artificial catchments was built

EUROPEAN JOURNAL OF ENVIRONMENTAL SCIENCES

Understanding how natural processes arise from complex interactions between particular processes ... more Understanding how natural processes arise from complex interactions between particular processes at small spatiotemporal scales and in turn how these processes form patterns at large spatiotemporal scales is one of the current principal questions in environmental science. The problem is very complicated, as in many cases, key processes are often studied by researchers in separate disciplines such as ecology, soil science or hydrology. One of the major obstacles is that the processes at a landscape scale are difficult to manipulate and, in many cases, even measure. In particular, the belowground processes are in many cases overlooked or at least understudied. Here we briefly describe a methodological solution used to cope with this problem and describe artificial catchments designed for experimental manipulation at the level of a landscape, called FALCON. This array has two treatments: one mimics a site reclaimed using an alder plantation and the other was left to unassisted primary succession. For each treatment, there were two replicates in four similar catchments. Individual catchments are hydrologically isolated from the environment and equipped with instruments, so that all the main processes and all significant flows of substances and energy in the ecosystem can be monitored, including the cycling of water, nutrients and gas between the ecosystem and the atmosphere. In addition, in each catchment there are sets of lysimeters, which allow the study of small-scale processes and how these can be extrapolated to the catchment scale. In addition, two lysimetric fields exist alongside the catchments for monitoring the effects of the experimental manipulation.

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Correction to: Analysis of environmental flow requirements for macroinvertebrates in a creek affected by urban drainage (Prague metropolitan area, Czech Republic)

Urban Ecosystems, Dec 15, 2017

The original version of this article unfortunately contained errors. The given name and family na... more

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Rainwater propagation through snowpack during rain-on-snow sprinkling experiments under different snow conditions

Hydrology and Earth System Sciences

The mechanisms of rainwater propagation and runoff generation during rain-on-snow (ROS) events ar... more The mechanisms of rainwater propagation and runoff generation during rain-on-snow (ROS) events are still insufficiently known. Understanding storage and transport of liquid water in natural snowpacks is crucial, especially for forecasting of natural hazards such as floods and wet snow avalanches. In this study, propagation of rainwater through snow was investigated by sprinkling experiments with deuterium-enriched water and applying an alternative hydrograph separation technique on samples collected from the snowpack runoff. This allowed us to quantify the contribution of rainwater, snowmelt and initial liquid water released from the snowpack. Four field experiments were carried out during winter 2015 in the vicinity of Davos, Switzerland. Blocks of natural snow were isolated from the surrounding snowpack to inhibit lateral exchange of water and were exposed to artificial rainfall using deuterium-enriched water. The experiments were composed of four 30 min periods of sprinkling, separated by three 30 min breaks. The snowpack runoff was continuously gauged and sampled periodically for the deuterium signature. At the onset of each experiment antecedent liquid water was first pushed out by the sprinkling water. Hydrographs showed four pronounced peaks corresponding to the four sprinkling bursts. The contribution of rainwater to snowpack runoff consistently increased over the course of the experiment but never exceeded 86 %. An experiment conducted on a non-ripe snowpack suggested the development of preferential flow paths that allowed rainwater to efficiently propagate through the snowpack limiting the time for mass exchange processes to take effect. In contrast, experiments conducted on ripe isothermal snowpack showed a slower response behaviour and resulted in a total runoff volume which consisted of less than 50 % of the rain input.

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Groundwater recharge and residence times evaluated by isotopes of hydrogen and oxygen, noble gases and CFCs in a mountain catchment in the Jizera Mts., northern Czech Republic

GEOCHEMICAL JOURNAL

The concept of residence times has developed from the understanding of groundwater age as a scala... more The concept of residence times has developed from the understanding of groundwater age as a scalar value to understanding of residence times as integrated values of individual ages of water components in a mixture (McCallum et al., 2014; Suckow, 2014). Young groundwaters contribute substantially to runoff generation in the humid mountainous environment of central and northern Europe. A large amount of work has been performed to understand groundwater pathways and travel times in small headwaters, primarily using stable isotopes (Tetzlaff et al., 2015; Teuling et al., 2010). Recent efforts also include the use of 3 H and SF 6 to identify more sustained flow components (Stewart et al., 2007) and 3 He/ 3 H to verify the modelling of groundwater geochemical evolution along flowpaths (Burns et al., 2003). Application of noble gases to address these questions has been very rare up to date, in particular in the Central European context (Wenninger et al., 2004). Previous studies in the experimental catchment Uhlířská in the Jizera Mts., northern Czech Republic, suggest that groundwater discharge to streams originates predominantly from the valley deluviofluvial granitic sediments, in combination with soil water in weathered layers on hillslopes during rainfall and snowmelt periods (Šanda et al., 2014). The primary objective of this study is to assess the time scales of groundwater flow in the

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