Jiri, Jirka Simunek

• PhD
• Distinguished Professor at University of California, Riverside

Vertical stratification is a fundamental characteristic of water bodies that significantly affects vertical convection and mixing dynamics. With the impact of climate change, thermal and chemical stratification in lakes and reservoirs has been exacerbated, leading to more pronounced environmental and ecological challenges. While previous studies ha...

Accurate precipitation predictions are crucial for addressing climate change impacts on water resources, especially in arid regions like Oman. Therefore, this study evaluates three machine learning models—Random Forest (RF), Multilayer Perceptron Neural Networks (MLP-ANN), and Kolmogorov-Arnold Neural Networks (KANNs)—to downscale and predict preci...

Stony soils represent a complex porous system, which makes the description of their water retention a challenge. This study aims to assess whether the description of water retention in stony soils requires a bimodal Water Retention Curve (WRC) and to test the corresponding soil hydraulic parameters in Hydrus-1D for simulating drainage experiments....

Biochar nanoparticles can act as carriers of pollutants in the groundwater, posing a threat to the environment. This study explored the transport and retention behavior of wood-based (NWBCs) and corn-residues-based (NCBCs) acid-modified biochar nanoparticles produced at different pyrolysis temperatures (at 400 °C and 700 °C). The effects of feedsto...

Monitoring reservoir water quality at different depths has been challenging due to its dynamic nature. While surface water quality parameters (WQPs) have been extensively studied, a significant gap exists in monitoring WQPs at various reservoir depths. This study addresses this gap by developing a copula framework to monitor subsurface WQPs based o...

Conducting field investigations of farmland irrigation patterns on a large scale is a time-consuming and labor-intensive task. The traditional approach of employing satellite remote sensing for large-scale visual assessments is impractical for identifying irrigation patterns due to interference caused by vegetation cover. To address this, we utiliz...

Intercropping has been widely practiced around the world due to its apparent advantages. However, the soil salt dynamic in the intercropping system has not yet been fully quantified, especially from the perspective of the combined impacts of brackish water irrigation and groundwater recharge. Therefore, a two-year field experiment was performed...

Drip irrigation with alternate use of surface water and groundwater (ADI) has been widely applied in arid regions to relieve the effects of heat stress on crop growth. However, the heat dynamics under ADI are still unclear, especially concerning the impacts of ADI on daily and seasonal fluctuations of soil temperature (Ts). Thus, a two-year experim...

Groundwater vulnerability maps are crucial for safeguarding groundwater quality. A research gap exists in using advanced data fusion techniques to identify areas subject to seawater intrusion. To address this gap, this research enhances the GALDIT method and applies diverse deep learning models, combined with machine learning techniques, to improve...

Colloid‐facilitated transport has been widely acknowledged as a significant contributor to surface water and groundwater pollution. Compared to water‐dissolved solutes, colloids are subject to a size exclusion effect (SEE) due to their inherent size when transported through porous media. However, only a few studies have quantitatively assessed SEE...

Plants on the land surface play a vital role in the hydrological water cycle as they transport soil water to the atmosphere through transpiration. Root water uptake (RWU) is considered a crucial step in this process as it is the first stage of transpiration, directly determining the actual transpiration (Ta) of plants. However, accurately measuring...

HYDRUS is a Windows-based modeling software package that can be used to analyze water flow and heat and solute transport in variably saturated porous media (e.g., soils or the vadose zone). The HYDRUS software includes an interactive graphics-based interface for data preprocessing, soil profile discretization, and graphic presentation of the result...

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In arid and semi-arid regions like Tunisia, irrigation water is typically saline, posing a soil and crop salinization risk and yield reduction. This research aims to study the combined effects of soil matric and osmotic potential stresses on tomato root water uptake. Plants were grown in pot and field experiments in loamy-clay soils and were irriga...

Ground‐mounted photovoltaic sites are often treated as impervious surfaces in stormwater permits. This ignores the pervious soils beneath and between solar arrays and leads to an overestimation of runoff. Our objective was to improve solar farm stormwater hydrology models by explicitly considering the disconnected impervious nature of solar design...

There has been an ongoing discussion about whether using functionalized biochar nanoparticles for pollutant removal is practical. The existing uncertainty surrounding functionalized biochar nanoparticles raises questions regarding their effectiveness in unraveling this problem. In this study, functionalized biochar nanoparticles were produced from...

The Brunswick modular framework for modeling unsaturated soil hydraulic properties (SHP) over the full moisture range was implemented in the Hydrus suite. Users can now additionally choose between four different variants of the Brunswick model: (i) van Genuchten–Mualem (VGM), (ii) Brooks–Corey, (iii) Kosugi, and (iv) modified van Genuchten. For dem...

The HYDRUS codes have become standard tools for addressing many soil, agricultural, environmental, and hydrological problems requiring the evaluation of various subsurface physical, chemical, and biological processes. There are now many thousands of HYDRUS users worldwide, with thousands of applications of the HYDRUS models appearing in the peer‐re...

Water scarcity and quality are critical impediments to sustainable crop production. In this study, HYDRUS-2D was calibrated using field measurements of water contents and salinities in the soil under wine grapes irrigated with river water (Rw, 0.32 dS/m). The calibrated model was then used to evaluate the impact of (a) four different water qualitie...

Rainfed wheat production systems are usually characterized by low-fertility soils and frequent droughts, creating an unfavorable environment for sustainable crop production. In this study, we used a processed-based biophysical numerical model to evaluate the water balance and nitrogen (N) dynamics in soils under rainfed wheat cultivation at low (21...

The new isotope module in HYDRUS‐1D can be used to infer the origin of root water uptake (RWU), a suitable dynamic indicator for agriculture and forest water management. However, evidence shows that the equilibrium fractionation between liquid water and water vapor within the soil is affected not only by soil temperature but also by soil tension. H...

The temporal origin of drainage, evaporation, and root water uptake (RWU) are indicators of ecosystem functioning that shed light on how natural and anthropogenic disturbances affect plant resilience and aquifer vulnerability. A virtual tracer experiment was carried out in HYDRUS-1D using data from a soil lysimeter planted with winter rye in Austri...

Nitrogen (N) applications can play a key role in achieving profitable wheat production in the low-fertility soils prevalent under rainfed conditions. The model-predicted N partitioning revealed that ammonia-nitrogen (NH4-N) contributed little to the plant N nutrition, and its concentration in the soil remained below 2 ppm throughout the crop season...

This study elucidates the behavior of Markov-Chains Monte Carlo ensemble samplers for vadose zone inverse modeling by performing an in-depth comparison of four algorithms that use Affine-Invariant (AI) moves or Differential Evolution (DE) strategies to approximate the target density. Two Rosenbrock toy distributions, and one synthetic and one actua...

The temporal origin of root water uptake and drainage provides insights into the impact of natural and anthropogenic disturbances on plant resilience and aquifer vulnerability. In-situ and virtual tracer experiments provide information on rainfall partitioning and transit times, which help to enhance the understanding of the hydrological response o...

We investigated the influence of climate change in the period 1951-2020 on shallow aquifers in the Brda and Wda outwash plains (Pomeranian Region, Northern Poland). There was a significant temperature rise (0.3 °C/10 years), which accelerated after 1980 (0.66 °C/10 years). Precipitation became increasingly irregular - extremely rainy years occurred...

Irrigated agriculture has been in a quandary of sustaining its productivity for centuries while attempting to cope with soil and water salinity issues that continue to devastate crop production. Several of the research gaps associated with current irrigation practices include how to assess leaching requirement (LR) and efficiency (LE) for different...

As a critical element in preserving the health of urban populations, water distribution systems (WDSs) must be ready to implement emergency plans when catastrophic events such as contamination events occur. A risk-based simulation-optimization framework (EPANET–NSGA-III) combined with a decision support model (GMCR) is proposed in this study to det...

The application of inverse modeling to determine the hydraulic properties of layered soils with rock fragments (RF > 2 mm) is associated with complex challenges such as selecting suitable hydraulic functions and defining a strategy to optimize many parameters. These two issues were addressed in this study by performing field drainage experiments in...

Soil salinization caused by shallow, saline groundwater represents a serious threat to field productivity, especially in arid regions with intense soil evaporation. Plastic film mulching (PM) has been increasingly applied to reduce soil evaporation and alleviate soil salinity stress. However, PM introduces into the soil a significant amount of pla...

Considering surface and subsurface interactions is imperative to predict water movement, water quantity and quality in the environment. However, substantial execution time and over-parameterization presently limit the applicability of integrated hydrologic models at larger scales. Herein, a new efficient coupling routine for one-dimensional (1D) su...

Biosolids are an important resource for agricultural practice but have recently received increased focus as a potential source of per- and polyfluoroalkyl substances (PFAS) in the environment. Few studies have investigated the transport of PFAS through the unsaturated zone under conditions relevant to biosolids application sites. Herein, the unsatu...

CONTEXT Intercropping systems have been widely used worldwide due to their high economic benefits and land-use efficiency. While it is well known that inter-species nutrition competition in intercropping systems leads to high production efficiency, the effects of different spatial arrangements of intercropping species on these mechanisms remain unc...

Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is typically used to quantify surface interactions between engineered nanoparticles (ENPs), soil nanoparticles (SNPs), and/or porous media, which are used to assess environmental risk and fate of ENPs. This study investigates the co-transport behavior of functionalized multiwalled carbon nanotubes (MWC...

Choosing a suitable process-oriented eco-hydrological model is essential for obtaining reliable simulations of hydrological processes. Determining soil hydraulic and solute transport parameters is another fundamental prerequisite. Research discussing the impact of considering evaporation fractionation on parameter estimation and practical applicati...

Drip irrigation with alternate use of fresh and brackish waters is an excellent irrigation strategy to overcome salt stress problems induced by brackish water. Understanding salt stresses in the soil profile and their relationship with crop growth is critical when optimizing irrigation strategies with alternate use of fresh and brackish waters. The...

When performing calculations or numerical simulations for the fate and transport of PFAS and other surface-active solutes in the vadose zone, accurately representing the relationship between the area of the air-water interfaces (Aaw) as a function of water saturation (Sw), and changes in that relationship resulting from changes in soil texture, are...

The creation of artificial dunes for coastal protection may have important consequences for freshwater lenses in coastal aquifers. The objective of this study was to compare the recharge processes below such a young dune with scant vegetation to an older dune covered by grass and herbaceous vegetation. To this aim, soil and water samples were colle...

Darcian, 2-D flows to subterranean holes are studied analytically (by the methods of complex analysis) and numerically (by HYDRUS). For flow towards two circular or quasi-circular tunnels, reconstructed as isobars generated by two sinks under a ponded homogeneous soil surface, the flow nets, the velocity vector fields, and Riesenkampf's seepage for...

Optimization problems in hydrological modeling are frequently solved using local or global search strategies, which either maximize exploitation or exploration. Thus, the elevated performance of one strategy for one class of problems is often offset by poor performance for another class. To overcome this issue, we propose a hybrid strategy, G-CLPSO...

Many different equations have been proposed to describe quantitatively one‐dimensional soil water infiltration. The unknown coefficients of these equations characterize soil hydraulic properties and may be estimated from a n record, {t∼i,I∼i}i=1n$\{ {\tilde t_i},{\tilde I_i}\} _{i = 1}^n$, of cumulative infiltration measurements using curve fitting...

Given the hazardous effects of sudden dam reservoir contamination — as might occur upon the intrusion of the fuel additive methyl tert-butyl ether (MTBE) — the contaminant’s effect on the quality of allocated waters requires careful study. Employed to determine optimal reservoir operational rules in the case of sudden MTBE pollution, a risk-based s...

Quantification of groundwater recharge is one of the most important issues in hydrogeology, especially in view of the ongoing changes in climate and land use. In this study, we use numerical models of 1D vertical flow in the vadose zone and the water table fluctuation (WTF) analysis to investigate local-scale recharge of a shallow sandy aquifer in...

The EU Nitrates Directive calls for urgent integration of process-oriented indicators of nitrate fate with map overlay approaches for assessing nitrate vulnerable zones (NVZs). In the region of Campania (southern Italy), groundwater contamination represents a serious concern because of the presence of intensive agricultural practices and livestock...

The use of Green Roofs (GRs) for domestic wastewater treatment and nitrogen (N) removal is an appealing opportunity to conjugate hydrological, energetic, and water quality benefits. However, the research in this direction has been limited to few experimental studies, while the role of numerical modeling for analysis and design has been overlooked....

California is increasingly experiencing drought conditions that restrict irrigation deliveries to perennial nut crops such as almonds and pistachios. During drought, poorer quality groundwater is often used to maintain these crops, but this use often results in secondary salinization that requires skilled management. Process-based models can help i...

Analytical solutions are obtained for water extinction from an axisymmetric crater, filled at t < 0 and depleted by evaporation and transient infiltration into a Gardner or capillarity-free homogeneous soil during the time interval 0 ≤ t ≤ Te. The extinction time Te is found for crater beds, the shapes of which are shallow cones, spherical, spheroi...

Soil salinity increases when growers are forced to use higher salinity irrigation waters due to water shortages. It is necessary to estimate the impact of irrigation water on soil properties and conditions for crop growth to manage the effects of salinity on perennial crops. Therefore, in this study, we monitored root zone salinity in five almond a...

Long-term use of recycled water (RW) for irrigation in arid and semiarid regions usually changes the soil solution composition and soil exchange characteristics, enhancing the risk for salinity and sodicity hazards in soils. This modelling study focuses on developing alternative management options that can reduce the potentially harmful impacts of...

Artificial capillary barriers (CBs) are used to improve root zone conditions as they can keep water and nutrients in the root zone by limiting downward percolation. Numerical analysis is one of the promising tools for evaluating CB systems’ performance during the cultivation of leafy vegetables. This study aims to investigate the effects of the CB...

Soil contains the largest terrestrial pool of organic matter, and the cycling of organic carbon in soils plays a crucial role in controlling atmospheric carbon dioxide (CO2) and global climate change. Although considerable progress has been made in previous modeling studies on the fate of soil organic matter (SOM), only a few models used a process-...

Optimization of nitrogen (N) fertigation is a formidable challenge involving complex interactions between water and N uptake and their effects on crop production. Numerical models can be useful in studying the interaction of multiple variables like those found in mechanistic simulations of N fertigation strategies. The physical aspects can often be...

Soil pollution from emerging contaminants poses a significant threat to water resources management and food production. The development of numerical models to describe the reactive transport of chemicals in both soil and plant is of paramount importance to elaborate mitigation strategies. To this aim, in the present study, a multiscale biophysical...

Ecohydrological processes are often evaluated by studying the fate of stable water isotopes. However, isotopic fractionation during evaporation is often ignored or simplified in current models, resulting in simulation errors that may be propagated into practical applications of stable isotope tracing. In this study, we adapted and tested the HYDRUS...

The use of plastic film mulching (PM) has steadily increased in the past few decades due to many advantages compared to no film mulching (NM). However, PM also has many drawbacks, such as producing plastic film residues and causing high temperatures at later crop growth stages. Thus, biodegradable film mulching (BM) has recently been used as an exc...

This study presents a conceptual Dual-Permeability Non-Equilibrium (DPNE) model that accounts for both physical and chemical non-equilibria to describe the reactive solute transport through a porous medium. A semi-analytical solution of the DPNE model is derived in the Laplace domain, which is then numerically inverted to obtain concentrations in d...

The authors appreciate Dr. Kabala's interest in our work and his commitment to protecting research work integrity and scientific records accuracy. They are of the utmost importance to us as well. After receiving the Comment, we made it our highest priority to respond, address the concerns raised, and carefully re‐examine our manuscript. This reply...

Enhanced water use efficiency (WUE) is the key to sustainable agriculture in arid regions. The installation of capillary barriers (CB) has been suggested as one of the potential solutions. CB effects are observed between two soil layers with distinctly different soil hydraulic properties. A CB helps retain water in the upper, relatively fine-textur...

Numerical simulation of three-dimensional water flow and solute transport in containerized variably saturated soilless substrates with complex hydraulic properties and boundary conditions necessitates high-resolution discretization of the spatial and temporal domains, which commonly leads to several million nodes requiring numerical evaluation. Eve...

The classical Barenblatt solution of an initial-boundary value problem (IBVP) to the parabolic Boussinesq equation, which gives a rectangular triangle of full saturation, propagating from a reservoir into an adjacent porous bank with a vertical slope, is shown to coincide with a solution of IBVP to the elliptic Laplace equation with a phreatic surf...

The hydraulic properties of the soil top layer may change during the growth period due to various factors such as wetting and drying cycles, tillage practices, and crop root growth. In this study, the potential of the assimilation method to estimate time-varying soil hydraulic parameters is explored. Four assimilation schemes, including the simulta...

Pakistan is facing severe water shortages, so using the available water efficiently is essential for maximizing crop production. This can be achieved through efficient irrigation practices. Field studies were carried out to determine the dynamics of soil water and the efficiency of water utilization for maize grown under five irrigation techniques...

Many arid and semi-arid regions of the world face challenges in maintaining the water quantity and quality needs of growing populations. A drywell is an engineered vadose zone infiltration device widely used for stormwater capture and managed aquifer recharge. To our knowledge, no prior studies have quantitatively examined virus transport from a dr...

In cold regions, freeze-thaw cycles play a critical role in many engineering and agricultural applications and cause soil water flow and heat transport studies to be much more complicated due to phase changes involved. A fully coupled numerical module for simulating the simultaneous movement of water, vapor, and heat during freezing-thawing periods...

Food contamination is a major worldwide risk for human health. Dynamic plant uptake of pollutants from contaminated environments is the preferred pathway into the human and animal food chain. Mechanistic models represent a fundamental tool for risk assessment and the development of mitigation strategies. However, difficulty in obtaining comprehensi...

Seepage through an aquifer, the hydraulic conductivity of which varies vertically, is studied by using the Dupuit-Forchheimer approximation (Girinskii’s potential) and numerically by FDM-MODFLOW and FEM-HYDRUS-2D. In urban water hydrology, the effect of compaction of the top stratum of an aquifer on the flow rate and the position of the water table...