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February 2009 - February 2010
February 2010 - present
November 2003 - November 2004
Publications
Publications (75)
The granitic Uhlirska headwater catchment with a size of 1.78 km2 is located in the Jizera Mountains in the northern Czech Republic and received among the highest inputs of anthropogenic acid depositions in Europe. An anal- ysis of sulphate (SO24–) distribution in deposition, soil water, stream water and groundwater compartments allowed to establis...
Reliable quantitative prediction of water movement and fluxes of dissolved substances – specifically organic carbon – at both the hillslope and the catchment scales remains a challenge due to complex boundary conditions and soil spatial heterogeneity. In addition, microbially mediated transformations of dissolved organic carbon (DOC) are recognized...
Ponded infiltration experiment is a simple test used for in-situ determination of soil hydraulic properties, particularly saturated hydraulic conductivity and sorptivity. It is known that infiltration process in natural soils is strongly affected by presence of macropores, soil layering, initial and experimental conditions etc. As a result, infiltr...
Shallow saturated subsurface flow is a dominant runoff mechanism on hillslopes of headwater catchments under humid temperate climate. Its timing and magnitude is significantly affected by the presence of preferential pathways. Reliable prediction of runoff from hillslope soils under such conditions remains a challenge.
In this study, a quantitative...
The fate of pesticides in tropical soils is still not understood as well as it is for soils in temperate regions. In this study, water flow and transport of bromide tracer and five pesticides (atrazine, imazaquin, sulfometuron methyl, S-metolachlor, and imidacloprid) through an undisturbed soil column of tropical Oxisol were analyzed using a one-di...
The availability of long-term data series of natural stable isotopes of water (18O and 2H) observed in a small mountainous headwater catchment provides an opportunity to study soil water partitioning and runoff generation processes. In this study, the analysis of the isotopic composition of rainwater, soil water, subsurface stormflow, groundwater,...
The solubility and mobility of copper (Cu) in soil is strongly influenced by the presence of dissolved organic carbon (DOC); however, the interactions between Cu and DOC are complex and not yet fully understood. In this study, Cu and DOC concentrations were measured monthly for two years in leachates from self-constructed lysimeters installed at in...
The idea of the study is to indicate direction-dependent differences in hydraulic conductivity, K(Se), and soil water diffusiv-ity, D(θ), as function of the volume fraction related to the fractional capillary potential for each of the characteristic pore size classes by extended anisotropy factors. The study is exemplary focused on a BwC horizon of...
The idea of the present study is to describe the spatially varying particle size distribution (PSD) along intact aggregate surfaces with the laser diffraction method (LDM) of four silty-loamy and OC enriched horizons of a Dystric Cambisol from the Uhlířská catchment (Czech Republic) with the laser diffraction method (LDM). Besides, the comparabilit...
The mechanical compaction of soil material of mineral landfill systems affects the continuity and connectivity of the complex soil pore network. A horizontally-oriented layering is intended to generate a slope-induced lateral water flow out of mineral capping systems that is sufficient to minimise the statutory required vertical percolation through...
In structured soils, clay-organic coatings are spatially distributed along macropore surfaces. Information on thickness and volume of coating material is essential for macropore-matrix mass exchange of water and solutes. However, their determination is difficult and fraught with uncertainty due to irregular shapes of macropore surfaces. The objecti...
In structured soils, water and reactive solutes can move preferentially through larger inter-aggregate macropores (biopores and cracks) and smaller intra-aggregate pores. Especially clay-organic coating material is of major importance for the exchange of water and solutes between macro- and micropores and the soil matrix by affecting the reactive t...
Green roofs, as an element of the green infrastructure, contribute to the urban heat island effect mitigation and the urban drainage outflow reduction. To achieve the desired functions, it is essential to understand the role of the individual roof layers and ensure their proper design.
A physically-based model was used to assess the hydrological an...
Residence and travel times of water in headwater catchments, or their smaller spatial units, such as individual hillslopes, represent important descriptors of catchments’ hydrological regime. In this study, travel time distributions and residence times were evaluated for a montane forest hillslope site. A two-dimensional dual-continuum model, previ...
Rising damp causes deterioration of masonry walls in many historical buildings. Although the phenomenon of capillary rise in porous structures is relatively well understood, reliable numerical modeling of the moisture regime, applicable to the assessment of current state as well as to the predictions of changes induced by various corrective moistur...
A new modeling approach was developed to facilitate simulations of soil water flow and energy transport during sporadic freezing–thawing episodes typical for the winter regime of humid-temperate continental climate. The approach is based on an accurate non-iterative algorithm for solving the highly non-linear energy balance equation during phase tr...
Parametrization of transformation and transport processes of dissolved organic carbon (DOC) in soils is challenging especially under variable hydrological conditions. In this study, DOC concentrations in stormflow were analyzed with a physically‐based modeling approach. A one‐dimensional dual‐continuum vertical flow and transport model was applied...
The coastal waters of Hawaii are extremely important for recreation as well as for the health of the marine environment. Non-point source pollution from storm runoff poses a great threat to surface water quality in Hawaii. The State of Hawaii Department of Transportation (HDOT) includes infiltration trenches as a best management practice (BMP) opti...
Terrestrial carbon export via inland aquatic systems is a key process in the global carbon cycle. It includes loss of carbon to the atmosphere via outgassing from rivers, lakes, or reservoirs and carbon fixation in the water column as well as in sediments. This review focuses on headwater streams that are important because their stream biogeochemis...
Core Ideas
A previous soil water flow model was extended to allow simulation of transient plant water storage.
Comparison with measured Norway spruce sap flow data indicates improved model performance.
The proposed algorithm can be easily incorporated into existing soil water flow models.
When describing the movement of water in a variably saturat...
In the context of soil water flow modeling, root water uptake is often evaluated based on water potential difference between the soil and the plant (the water potential gradient approach). Root water uptake rate is modulated by hydraulic resistance of both the root itself, and the soil in the root vicinity. The soil hydraulic resistance is a functi...
The heterogeneity of water flow was evaluated in sandy loam soil covered by grass. The radioactive tracer infiltration experiment was performed at two parallel plots with different irrigation intensities. Effective cross section and degree of preferential flow parameters were used to evaluate flow regime during the experiment. For both plots, the h...
Shallow saturated subsurface flow, frequently observed on hillslopes of headwater catchments in humid temperate climates, often dominates hydrologic responses of the catchments to major rainfall events. Typically, these responses are significantly affected by the presence of preferential flow. Reliable prediction of runoff from hillslope soils unde...
Transport of radioactive iodide 131I− in a black clay loam soil under spring barley in an early ontogenesis phase was monitored during controlled field irrigation experiment. It was found that iodide bound in the soil matrix could be mobilized by the surface leaching enhanced by mechanical impact of water drops and transported below the root zone o...
The heterogeneity of water flow and solute transport was assessed during radioactive tracer infiltration experiment in a black clay loam soil using modified methods to estimate the effective cross section (ECS) and the degree of preferential flow (DPF). The results of field and numerical experiments showed that these parameters characterized the he...
Preferential flow (PF) depends on processes and structures in soil at the small scale and can affect flow and transport processes at much larger scales. For studying PF processes, the discharge and solute effluent from subsurface drained experimental fields has frequently been used as a field-integrated signal that included combined effects of macr...
A simple macroscopic vertically distributed plant root water uptake
(RWU) model based on traditional water-potential-gradient formulation
(Vogel et al., 2013), in which the uptake rates are directly
proportional to the potential gradient and indirectly proportional to
the local soil and root resistances to water flow, was tested. This RWU
modeling...
Recurrent ponded infiltration experiments on undisturbed soil samples
have revealed a significant flow instability characterized by a decrease
in the steady-state flow rate of the second infiltration run, conducted
into wet soil, compared with the first infiltration run, conducted into
drier soil. It has been hypothesized that this decrease was cau...
Stable isotopes of water naturally occurring in rainwater have the
potential to reveal principal transport mechanisms at multiple scales -
from soil profile to hillslope and catchment scale. In this
contribution, we study transport processes at the hillslope scale by
combining field observations of hillslope discharge and the associated
oxygen-18 c...
Recurrent ponded infiltration experiments on undisturbed samples of coarse sandy loam have revealed a significant flow instability characterized by a decrease in the steady-state flow rate of the second infiltration run, conducted into wet soil, compared with the first infiltration run, conducted into drier soil. It has been hypothesized that this...
One of the principal components of mass exchange within the soil plant atmosphere system is soil water extraction by plant roots. Adequate evaluation of water extraction is a prerequisite for correct predictions of plant transpiration and soil water distribution in the root zone. The main objective of the present study is to contribute to the devel...
Shallow subsurface runoff is one of the most important mechanisms determining hydrological responses of headwater catchments to rainstorms. In this study, a simplified approach combining one-dimensional dual-continuum vertical flow in a variably saturated soil profile and one-dimensional saturated flow along the soil-bedrock interface was used to s...
In the absence of overland flow, shallow subsurface runoff is one of the most important mechanisms determining hydrological responses of headwater catchments to rainstorms. Subsurface runoff can be triggered by preferential flow of infiltrating water frequently occurring in heterogeneous and structured soils as a basically one-dimensional (1D) vert...
The use of nuclear magnetic resonance (MR) and X-ray computed tomography
(CT) scanning is now well established in soil science and subsurface
hydrology. Recurrent ponded infiltration test was performed on small
undisturbed soil sample and further complemented with the MR and CT
scanning techniques. The experiment reveals complex water regime
accomp...
The temporal changes of saturated hydraulic conductivity caused by
occurrence of air phase discontinuities play an important role in water
flow and solute transport studies. Laboratory recurrent ponded
infiltration experiment on undisturbed soil sample reveals significant
flow instability characterized by a decrease of the steady state flow
rates b...
Physically based tier-II models may serve as possible alternatives to expensive field and laboratory leaching experiments required for pesticide approval and registration. The objective of this study was to predict pesticide fate and transport at five different sites in Hawaii using data from an earlier field leaching experiment and a one-dimension...
Subsurface drained experimental fields are frequently used for studying
preferential flow (PF) in structured soils. Considering two-dimensional
(2-D) transport towards the drain, however, the relevance of mass
transfer coefficients, apparently reflecting small-scale soil structural
properties, for the water and solute balances of the entire drained...
In Hawaii, pineapple is typically grown in raised beds covered with impervious plastic mulch. Field measurements of a commonly used herbicide (bromacil) mass beneath mulch-covered pineapple beds and inter-bed open areas revealed that open areas contained a mass of bromacil about 3.5 times greater than was originally applied, based on label instruct...
The transport of solutes in soils, and its intensification due to preferential flow, plays crucial role when problems related to the groundwater pollution are dealt with. The objective of this study was to examine transport of cadmium (Cd) in response to an extreme rainfall event for three different soils using numerical modeling. The 115mCd2+ conc...
Dual-continuum models are useful for describing flow in porous systems with significant local pressure disequilibrium between slow moving water, contained in the porous matrix, and fast moving water in preferential pathways. The formation and intensity of preferential flow depends on the contrast between the hydraulic properties of the two flow dom...
Soil water dynamics at an experimental hillslope site is studied by means of a one-dimensional dual-continuum model. The model is based on Richards' equation for vertical soil water flow and the advection-dispersion equation for transport of the stable isotope (18)O. The water body contained in the soil-matrix pore space and the one transmitted thr...
Disk infiltrometers are established as standard devices for measuring soil surface hydraulic properties. This study explored the validity of a semiempirical approach that is used to obtain estimates of the near-saturated hydraulic conductivity from disk infiltrometer data. The approach was compared with two other estimation expressions. The analysi...
Disk infiltrometers are widely used devices for quick and convenient measurement of soil surface hydraulic properties. In the present study, several estimation procedures, commonly used for the determination of near-saturated hydraulic conductivity from disk infiltration data, are evaluated using numerical modeling of three-dimensional axisymmetric...
The field pesticide leaching experiment, conducted at five different sites in Hawaii, USA was subject to numerical modeling. The one-dimensional model, based on Richards equation for water flow and the advection-dispersion equation for solute transport was used. At each site, pressure head data and chemical concentration profiles were measured duri...
Following the discovery of pesticides in wells, the Hawaii Department of Agriculture (HDOA) supported research to evaluate the likelihood of pesticide leaching to the groundwater in Hawaii. The aim of this study was to evaluate the relative leaching pattern of five pesticides at five different sites on three islands and to compare their leaching be...
One of the most important properties, affecting the flow regime in the soil profile, is the topsoil saturated hydraulic conductivity (K s). The laboratory-determined K s often fails to characterise properly the respective field value; the K s lab estimation requires labour intensive sampling and fixing procedures, difficult to follow in highly stru...
Preferential movement of water in macropores plays an important role when the process of ponded infiltration in natural porous
systems is studied. For example, the detailed knowledge of water flow through macropores is of a major importance when predicting
runoff responses to rainfall events. The main objectives of this study are to detect preferen...
Two-dimensional single- and dual-permeability simulations are used to analyze water and solute fluxes in heterogeneous lignitic mine soil at a forest-reclaimed mine spoil heap. The soil heterogeneity on this experimental site "Bärenbrücker Höhe" resulted from inclined dumping structures and sediment mixtures that consist of sand with lignitic dust...
The aim of our study is to seek more versatile and robust solution of flow and transport problems involving preferential flow. Dual-continuum models of soil water movement are useful whenever significant local pressure disequilibrium, between slow moving water contained in the soil matrix and fast moving water in the preferential pathways, is encou...
An adequate and physically sound description of the local scale soil-plant-atmosphere (SPA) processes and their spatiotemporal variability is essential for our ability to predict the impact of possible future changes of governing system parameters. In this contribution we focus on the role of the various components of the SPA system and their impac...
This study aims at evaluation of soil water dynamics in a shallow hillslope soil. The transport of stable oxygen isotope 18O in a variably saturated soil profile is simulated by means of a one-dimensional dual-continuum model. The model is based on Richards' equation for the water flow and advection-dispersion equation for the isotope transport. Th...
Two-dimensional single- and dual-permeability simulations are used to analyze water and solute fluxes in heterogeneous lignitic mine soil at a forest-reclaimed mine spoil heap. The soil heterogeneity on this experimental site "Barenbrucker Hohe" resulted from inclined dumping structures and sediment mixtures that consist of sand with lignitic dust...
Dual continuum models of soil water movement are useful whenever significant local pressure disequilibrium between slow moving water, contained in the soil matrix, and fast moving water, in the preferential pathways, is encountered. The present study focuses on the situation where the volumetric fraction of the preferential flow domain is variable...
The simulation of preferential flow in structured soil using dual-porosity models requires separate sets of the hydraulic, transport, and mass transfer parameters and of the boundary conditions. Analyses of tracer experiments with two-domain models are limited by constraints in specifying separate boundary conditions (BCs) for each pore domain. The...
Extreme floods represent an increased risk for urban areas and agriculture. Time to time the protective earth dams are destroyed by a suddenly increased amount of water with destroing or even cathastrophic consequences. A numerical study of the soil moisture development within the earth body during the flood is simulated under a selection of bounda...
Groundwater is the primary source of drinking water for all the islands of Hawaii. Past agricultural practices have led to the contamination of groundwater in certain locations. As a result, the state of Hawaii emphasizes the prevention of contamination of groundwater from the leaching of pesticides. Hawaii currently uses a simple ( Tier I) screeni...
Adequate modeling of infiltration into heterogeneous structured soils from ponded sources represents an important scientific problem with numerous implications for practical hydrological tasks, e.g. estimation of irrigation demand, runoff prediction and contaminant transport in the vadose zone. Reliable predictions of the three-dimensional flow of...
Cadmium penetration into a sandy-loam soil during the field ponded infiltration at Kráľovska lúka site in Southern Slovakia was observed in a controlled experiment using a radioactive tracer technique. Quite deep 115m Cd penetration (65 cm beneath the soil surface) gives evidence of the particle-facilitated transport of cadmium through preferential...
Preferential flow has been hypothesized as an important factor for chemical leaching from tile-drained agricultural fields with structured soils originating from glacial till sediments. Previous studies showed that one-dimensional single-porosity models (1D-SPM) failed and that one-dimensional dual-permeability models (1D-DPERM) were limited in exp...
Cadmium penetration into a sandy-loam soil during the field ponded infiltration at Kralovska luka site in Southern Slovakia was observed in a controlled experiment. Adsorption of cadmium was examined using the radioactive tracer techniques in laboratory batch tests. Quite deep (115m)Cd penetration during the field experiment (65 cm beneath the soil...
Numerical modelling is used to analyze the transport of cadmium in response to an extreme rainfall event. The cadmium transport
through the soil profile was simulated by the one-dimensional dual-permeability model, which assumes the existence of two
mutually communicating domains: the soil matrix domain and the preferential flow domain. The model i...
This paper focuses on numerical modelling of soil water movement in response to the root water uptake that is driven by transpiration. The flow of water in a lysimeter, installed at a grass covered hillslope site in a small headwater catchment, is analysed by means of numerical simulation. The lysimeter system provides a well defined control volume...
The main objective of this study is to assess the effect of hysteresis of soil hydraulic properties on model predictions of soil water movement in a variably saturated soil. The model predictions are generated by the S1D model, which is based on numerical solution of one-dimensional Richards’ equation. The analysis is made for a loamy sand soil loc...
Past incidences of ground water contamination from nematicides and herbicides has focused on a progressive approach to pesticide registration in Hawaii. The state of Hawaii, in the early 1990's made an assessment of the pesticides used in Hawaii and their potential to leach into ground water. Since there is increased pressure to bring new agricultu...
Intensive use of pesticides in agriculture inevitably poses an increased
threat to groundwater. Recent findings of pesticide residues in selected
drinking water wells in Hawaii brings further attention to this problem
since the primary source for potable water in Hawaii is groundwater from
basal or dike-confined aquifers. A challenging research pro...
Three new herbicides, a fungicide, and an insecticide were tested for their ability to leach in various tropical soils in Hawaii. In addition, atrazine and bromide ions were used as two reference chemicals in the study. Label rates of these chemicals for agriculture or insecticidal use were applied to tilled soils. Five test sites at differing topo...
A dual-permeability model (S_1D_DUAL) was developed to simulate the transport of land-applied pesticides in macroporous media. In this model, one flow domain was represented by the bulk matrix and the other by the preferential flow domain (PFD) where water and chemicals move at faster rates. The model assumed the validity of Darcian flow and the ad...
Cadmium penetration into a sandy-loam soil during the field ponded infiltration at Kralovska luka site in Southern Slovakia was observed in a controlled experiment. Transport of cadmium adsorbed on soil particles < 0.01 mm was examined using radioactive tracer techniques in laboratory batch tests. Quite deep 115Cd penetration (65 cm beneath the soi...
Preferential flow was hypothesized as possible cause for chemical
leaching from tile-drained agricultural fields with structured soils
originating from glacial till sediments at Bokhorst experimental site.
Although tile water outflow peaks could somehow be reproduced,
single-porosity models were unable to describe leaching patterns,
characterized b...
Funneled flow is often reported when a capillary barrier at the interface between two overlain layers impedes vertical flow. As a consequence water flows in the upper layer in the direction of the lower inclined layer. Conditions that create possibility for funnel flow may be given by e.g. wedge shaped coarse sand layer or impermeable layer in engi...