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Nutrient availability after fertilising agricultural soils is affected by many factors, including soil moisture conditions and physicochemical properties. Herein, the availability of potassium in soil enriched with biochar is studied, considering either saturated or unsaturated moisture conditions and questioning key ion exchange approaches, such as equilibrium exchange (E.E.) and kinetic exchange (K.E.). Potassium release is simulated from a soil–biochar mixture of 0, 0.5, 1 and 2% by coupling HYDRUS-1D and PHREEQC models. The water flow, mass transport and geochemical processes are simulated for a cultivation period that imitates agronomic and environmental conditions of a common agricultural field in Northern Greece. Potassium is released gradually during the irrigation period in the case of unsaturated flow conditions as opposed to its complete release over a few days in the case of saturated flow conditions in the soil. Regarding ion-exchange processes, the soluble amount of potassium is more readily available for transport in soil solution when using the E.E. approach compared to the K.E. approach that assumes a kinetically controlled release due to interactions occurring at the solid–solution interface. The increased proportion of biochar in soil results in a doubling of available potassium. Among the four modelling schemes, although the total mass of potassium released into soil solution is similar, there is a significant variation in release time, indicating that simplified saturated conditions may lead to unrealistic estimates of nutrient availability. Further experimental work will be valuable to decrease the uncertainty of model parameter estimation in the K.E. approach.

Stony soils that have a considerable amount of rock fragments (RFs) are widespread around the world. However, experiments to determine the effective soil hydraulic properties (SHPs) of stony soils, i.e., the water retention curve (WRC) and hydraulic conductivity curve (HCC), are challenging. Installation of measurement devices and sensors in these soils is difficult, and the data are less reliable because of their high local heterogeneity. Therefore, effective properties of stony soils especially under unsaturated hydraulic conditions are still not well understood. An alternative approach to evaluate the SHPs of these systems with internal structural heterogeneity is numerical simulation. We used the Hydrus 2D/3D software to create virtual stony soils in 3D and simulate water flow for different volumetric fractions of RFs, f. Stony soils with different values of f from 11 % to 37 % were created by placing impermeable spheres as RFs in a sandy loam soil. Time series of local pressure heads at various depths, mean water contents, and fluxes across the upper boundary were generated in a virtual evaporation experiment. Additionally, a multistep unit-gradient simulation was applied to determine effective values of hydraulic conductivity near saturation up to pF=2. The generated data were evaluated by inverse modeling, assuming a homogeneous system, and the effective hydraulic properties were identified. The effective properties were compared with predictions from available scaling models of SHPs for different values of f. Our results showed that scaling the WRC of the background soil based on only the value of f gives acceptable results in the case of impermeable RFs. However, the reduction in conductivity could not be simply scaled by the value of f. Predictions were highly improved by applying the Novák, Maxwell, and GEM models to scale the HCC. The Maxwell model matched the numerically identified HCC best.

Human urine concentrates 85% of the nitrogen and 65% of the phosphorus excreted by humans, making it a potential alternative crop fertilizer. However, knowledge gaps remain on the fate of nitrogen in situations favouring NH3 volatilisation and on the availability of P from urine. This study aimed at identifying the fate of nitrogen and phosphorus supplied by human urine from source separation toilets in a calcareous soil. To this end, a spinach crop was fertilized with 2 different doses of human urine (170 kgN.ha-1 + 8.5kgP.ha-1 and 510 kgN.ha-1 + 25.5 kgP.ha-1) and compared with a chemical fertiliser treatment (170 kgN.ha-1 + 8.5kgP.ha-1) and a water treatment. The experiment was conducted in 4 soil tanks (50 cm depth) in greenhouse conditions, according to a randomized block scheme. We monitored soil mineral nitrogen over time and simulated nitrogen volatilisation using Hydrus-1D and Visual Minteq softwares. We also monitored soil phosphorus pools, microbial biomass CNP, soil pH and electrical conductivity. Only an excessive input of urine affected soil pH (decreasing it by 0.2 units) and soil conductivity (increasing it by 183%). The phosphorus supplied was either taken up by the crop or remained in the available P pool. Ammonium seemed to be nitrified within about 10 days after application. However, both Visual Minteq and Hydrus models estimated that more than 50% of the nitrogen supplied was lost by ammonia volatilisation. Overall, our results indicate that direct application of urine to a calcareous soil is possible without harming soil properties, but that heavy losses of volatilised nitrogen are to be expected.

Recent flooding events, such as the one in Germany 2021 have caused irreversible damages to infrastructure and lives. The aftermath of events like these have underlined the importance of an accurate risk management by predicting them in urban areas. This is done by hydrological modelling in which topography and presence of hardened surface often determine the magnitude of the flood. However, the contributory part from green areas to a flooding event is often simplified by a runoff coefficient not taking all of the soil hydraulic properties into account. This thesis aims to study the surface runoff generation from three different soil types from different green urban areas in Uppsala, Sweden. Simulations have been conducted using the modelling tool Hydrus 1-D and two different types of rainfall-runoff simulations were investigated. Firstly, a 25-year historic rain series was simulated to investigate what soil moisture content was present in the soils before large rain events and what the main driving force for surface runoff generation was. The second part of the simulations was conducted using five type hyetographs depicting large rain events in Sweden. The aim of these simulations was to further investigate main driving forces for surface runoff generation and to examine if the temporal distribution of a rain event effect the surface runoff generation. The results showed that the soil moisture content present in the soils before large rain events were very close to the field water holding capacity and that the main driving force for surface runoff generation on the studied sites was peak precipitation intensity, but also that the mean precipitation intensity and soil moisture had a significant effect within a 95 % confidence interval. The hyetograph simulations showed that the temporal distribution of a rain event effects the surface runoff generation on the studied soil, with the events whose peak came later generally generated more surface runoff.

Intensive agricultural practices increase agrochemical pollution, particularly nitrogen (N) based fertilizers, which present an environmental risk. This study aims to evaluate long-term (2009– 2020) data on soil water regime and nitrate dynamics at an agricultural experimental site on fine-textured soils and to better understand the implications of N management in relation to groundwater pollution. The field site is located in the Biđ field (eastern Croatia), in the proximity of the Sava river. Zero-tension lysimeters were installed at six selected locations. Lysimeters were used to monitor the water regime, i.e., outflows in which nitrate concentration was measured, while additional soil- water samples were collected via 4 and 15-meter- deep monitoring wells. Soil hydraulic parameters were estimated by combining the laboratory measurements, and estimation in RETC software. Water regime and nitrate leaching in lysimeters were simulated using HYDRUS-1D for each year to allow crop rotation and to evaluate their effects individually. The HYDRUS-1D model successfully reproduced lysimeter outflows and nitrate dynamics, which was confirmed with high R2 values (water: 93% above 0.7, and nitrate: 73% above 0.7) indicating the good performance of the model simulating nitrification chain reactions. Principal component analysis (PCA) was performed to identify the relationships among all soil properties and environmental characteristics. The results showed the complex interaction of soil hydraulic properties, precipitation patterns, plant uptake, and N application. All locations have a decreasing trend of nitrate leaching over the investigation period. Most of the lysimeter outflows and elevated nitrate concentrations were connected to the wet period of the year when the soil was saturated, and evapotranspiration was low. The results of this study show that it is important to optimize N fertilizer applications for each particular environmental condition to reduce nitrate loss. The study indicates the importance of long-term field studies, key for agro-hydrological modeling and the improvement of agricultural practices.

Due to the high cost of the large-scale measurement of heavy metals, the use of statistical land models and techniques is one of the proper ways to study their distribution and level of pollution. The study area, is agricultural lands of south Tehran in Iran. Municipal wastewater is often used for irrigation agricultural lands under surface irrigation method. To study the distribution of heavy metals including copper, nickel, and lead, the ordinary kriging method in the GIS environment was used. In addition, one-dimensional HYDRUS modeling of water flow and heavy metals in the soil environment was simulated up to a depth of 50 cm for 210 days and the concentration of heavy metals in the depth was simulated. Distribution of lead element in soil surface with spherical model showed that its variation was in the range of 20–70 mg/kg. These values were 50–60 mg/kg for copper and 30 mg/kg for nickel. Investigation of heavy metal concentrations in soil profiles using the HYDRUS-1D model showed that the major accumulation of heavy metals occurred in the surface layer of soil at a depth of 0–15 cm that was higher than the permissible level.

Seepage well is an emerging Low Impact Development (LID) technology that can effectively control the storm runoff. However, its rainwater infiltration rate and storage capacity still require further enhancement. By setting a horizontal infiltration structure at the bottom of conventional rainwater seepage well (CSW), an enhanced seepage well (ESW) was proposed in this study, and its infiltration performances compared with the permeable pavement (PP) and the CSW were systemically investigated using static infiltration experiment and HYDRUS-2D simulation. The results showed that the infiltration efficiency of ESW was significantly higher than that of PP and CSW, and the process of water infiltrated through soil mainly controlled the macroscopic infiltration rate. The Nash-Sutcliff Efficient (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model, and the results of NSE values greater than 0.75 (varied between 0.75 and 0.91) confirmed the applicability of HYDRUS-2D to describe correctly the hydraulic behavior of the ESW system. Simulation infiltration tests showed that the ESW performed a higher average infiltration rate and fewer total runoff volume than the CSW, indicating the effectively enhancement of the infiltration and water retention capacity of ESW, especially under heavy rainfall intensities. Additionally, the ESW system exhibited an excellent runoff-control and rainwater retention capacity in an actual rainfall scenario.

Improper design and management of the cover layer of a sanitary landfill has been proven to produce harmful environmental impacts on the environment. One alternative at hand is to develop scenarios based on simulation of physical and computational models to represent the expected field water balance of a landfill coverage layer. This paper investigates the design of a sanitary landfill final cover in the municipality of Seropédica, which is located at the state of Rio de Janeiro - Brazil. More specifically, the compact soil coverage, which is widely used for landfill final cover of municipal solid waste, is evaluated in contrast to vegetation cover by grass, vegetation cover by brachiaria and capillary barrier. To accomplish such task, hydrometeorological forcing conditions, namely daily rainfall and temperature, were retrieved from the Anchieta weather station, which is situated nearby the study area. The Hydrus 1D and 2/3 D computational codes were employed to develop a set of scenarios to follow the contamination plume evolution within the landfill along the time frame of 20 years with some degree of reliability. It should be noted that the performed evaluation indicates the possibility to control the leachate release and consequently to avoid contaminating the environment, notably to prevent soil and water resources pollution. Vegetation cover by grass and brachiaria showed important control mechanisms with respect to the movement of the contaminant plume. In addition, it should be noticed that the best results for the landfill final cover were achieved for the capillary barrier, while poor performance results were obtained for the commonly employed compact soil. RESUMO O projeto e a gestão inadequados da camada de cobertura de um aterro sanitário produzem impactos ambientais prejudiciais ao meio ambiente. Uma alternativa disponível é desenvolver cenários baseados na simulação de modelos físicos e computacionais para representar o balanço hídrico que se espera que ocorra em uma camada de cobertura do aterro por meio de um experimento de campo. O presente trabalho investiga o projeto de cobertura final de um aterro sanitário no município de Seropédica, localizado no estado do Rio de Janeiro - Brasil. Mais especificamente, a cobertura compacta do solo, que é amplamente utilizada para a cobertura final de aterro de resíduos sólidos urbanos, é avaliada em contraste com a cobertura vegetal por gramíneas, cobertura vegetal por braquiária e barreira capilar. Para realização dessa tarefa, forçantes hidrometeorológicas, nomeadamente precipitação e temperatura na escala diária, foram obtidas da estação meteorológica de Anchieta, situada nas proximidades da área de estudo. Os códigos computacionais Hydrus 1D e 2/3 D foram empregados para desenvolver um conjunto de cenários para acompanhar a evolução da pluma de contaminação no interior do aterro ao longo do período de 20 anos com algum grau de confiabilidade. Ressalta-se que a avaliação realizada indica a possibilidade de controlar a liberação de chorume e, consequentemente, de evitar a contaminação do meio ambiente, notadamente para prevenir a poluição do solo e dos recursos hídricos. A cobertura vegetal por gramíneas e braquiárias apresentou importantes mecanismos de controle com relação ao movimento da pluma contaminante. Além disso, deve-se notar que os melhores resultados para a cobertura final do aterro foram alcançados para a barreira capilar, enquanto que os resultados de baixo desempenho foram obtidos para o solo compacto comumente empregado.

Understanding the characteristics of soil solute transport is fundamental to the design and management of furrow irrigation systems. This study determined the soil hydraulic and solute transport parameters by inverse solution with HYDRUS-2D and then verified them. The experimental data were obtained from the infiltration of clay loam and sandy loam of different potassium nitrate (KNO3) concentrations under furrow irrigation. Then, the initial soil water content (θ0), KNO3 concentration, and water depth (h0) affecting the transport characteristics of nitrate nitrogen (NO3−-N) and potassium (K+) were analyzed. The results indicated that the soil hydraulic and solute transport parameters determined from the inversion solution with HYDRUS-2D were reliable. The soil saturated water content, saturated hydraulic conductivity, and empirical parameter n in the van Genuchten–Mualem model increase with the increase of KNO3 concentrations, whereas the empirical parameter a shows a decreasing tendency. The distribution range of NO3−-N increased with the increases of θ0 and the KNO3 concentration, which had barely any effect on the range of K+ distribution. The horizontal distribution range of NO3−-N and K+ increased with the increase of h0, but it had no obvious influence on the vertical range. HIGHLIGHTS Soil hydraulic and solute transport parameters were determined by inverse solution with HYDRUS-2D, and then the reliability was verified.; θn, n and Ks (VG-M model) increased with increasing KNO3 concentration, while a exhibited a decreasing trend; The initial soil water content, KNO3 concentration and water depth have an obvious effect on the distribution of NO3−-N.; K+ was mainly distributed within 10 cm of the furrow bottom.

Parameterization of theeffective properties as input in hydrogeological models for simulating water flow is a time consuming and costly process, and it is characterized by high uncertainty because of the spatial variability of soil properties. Integrating visible-near-infrared spectroscopy (vis-NIRS) models and a developed pedotransfer function, a hydrogeological tool was suggested by Varvaris et al. in 2019 for estimating the hydraulic properties used in an equilibrium approach. In the current study, the proposed concept was further expanded for assisting on a rapid and inexpensive parameterization of effective parameters in nonequilibrium models. In our approach, the soil-water retention curves for the wet and hyper-dry ends were predicted using existing vis-NIRS calibration models for obtaining the parameters for the Campbell retention model and the Campbell and Shiozawa model, respectively. The HYDRUS-2D software package was used to simulate tile drainage discharge in a loamy structured field using as initial input hydraulic parameters the output from the suggested concept. The estimated parameters were validated based on measured hydraulic properties in the laboratory. Two-dimensional models incorporating nonequilibrium flow were used to evaluate the ability of each approach to predict the tile drainage discharge: a single-porosity with modified van Genuchten function, a dual-porosity model, and a dual-permeability model. All approaches gave a fairly good fit to the hydrograph features for both calibration and validation datasets with dual-porosity to present the highest predictive ability. Finally, the suggested initial parameterization concept proved its potential to be used as an alternative for covering the absence of measured data of soil hydraulic properties.

In this study, a tracer field experiment was conducted to study the temporal dynamics of bromide movement in a loamy tile-drained agricultural landscape. Moreover, tritium leaching experiments were performed on undisturbed soil columns from the same field. The HYDRUS-2D software package was used to model water and solute transport. Three water flow models developed in Part 1-a single-porosity approach with modified soil hydraulic functions (SP), a dual-porosity approach (DP), and a dual-permeability approach (DUP)-were used as a foundation for building solute transport models, of which the initial parameterization was based on a suggested hydrogeological tool from previous studies. The selected solute transport models were an SP, an SP with immobile water, a DP, a DUP, and a DUP with immobile water. The model predictions were compared against measurements of bromide concentrations in soil-water. The DP captured the degree of the initial peaks and predicted well the shape of the observed concentrations. However, DP presented low capability to match the timing of bromide concentration peaks. In contrast, the DUP with immobile water illustrated better predictive ability by introducing an additional pore region into the matrix domain. Validation of field-scale solute transport models was implemented using the data from the following leaching experiments. The already suggested parameterization concept was further evaluated for its capability to provide a sufficient initial representation of the internal pathways. The output from such hydrogeological studies shows that macropores and their interconnection with tile drains are key to understanding the water flow and solute transport processes in loamy structured soils.

Landslide susceptibility and water balance in the soil, in the community of Lagoa Encantada, Recife Metropolitan Area, Brazil, were assessed using the computational models SINMAP and HYDRUS-1D. The SINMAP input parameters were the physical and hydrodynamic characteristics of the soil, evidence of landslides and the DEM; and for the HYDRUS-1D model, the hydraulic parameters of the soil. For both programs, simulations were also carried out, based on the rain recorded in the area. The soil was classified using the Unified Soil Classification System (USCS). To assess infiltration processes that cause landslides, HYDRUS-1D was used, under the same scenarios simulated by the SINMAP model and also in the evaluation of the infiltrated volume, in real landslides. The SINMAP results (susceptibility maps) show a 71% increase in the susceptible area (SI < 1; SI = stability index) between the two precipitation scenarios, and are consistent with evidence of landslides. The HYDRUS-1D results complement SINMAP results and suggest that infiltration values for simulated scenarios were similar to those of real landslides. It is concluded that it is possible to map areas of greater instability and to predict possible landslides in different precipitation scenarios, by quantitatively assessing the infiltrated volume that contributes to the destabilization of the soil.

Alternate wetting and drying (AWD) practice in rice cultivation can save a significant amount of irrigation water compared to conventional practice. This practice involves a soil moisture stress-based irrigation scheduling and possibly affects the nitrogen transport in the farm fields. In this study, non-weighing lysimeter plots were used to understand the nitrogen transformation, transport and balance of rice soil under AWD practice. The lysimeter data sets were used to simulate the nitrogen transport for no soil moisture stress (NS: 0 cm), mild soil moisture stress (MS: 450 cm) and severe soil moisture stress (SS: 700 cm)-based irrigation scheduling by using Hydrus-1D model. The Hydrus-1D model was able to simulate N transport ( $${NH}_{4}^{+}-N$$ and $${NO}_{3}^{-}-N$$ ) from the ponding water to the soil–plant system for both calibration and validation datasets. The simulation results indicated that the applied N was mostly concentrated within the puddled (top) layer but slightly decreased with the increase in the soil moisture stress. The N crop uptake and leaching loss were decreased by 6% and 38%, in MS and by 15% and 52% in SS, respectively, when compared to NS (flooded rice). Both volatilization and denitrification losses were increased by 14 and 7% in MS, and by 17 and 7% in SS, respectively, when compared to NS. The Hydrus model can be used as a management tool to determine the appropriate soil moisture stress in the puddled layer for which the required N nutrients are sufficiently available to the rice crop and the N loss to the environment can be controlled.

Study region Dudu station, Rajasthan, India Study focus Rainwater harvesting can be used as a method to recharge aquifers. This can happen with a variety of scales and technologies. One such example is shallow infiltration ponds (Chaukas) which recharge groundwater and increase soil moisture facilitating pastureland development. A HYDRUS-1D model was used to estimate potential groundwater recharge. The model was calibrated using field data from 2019 and validated using data from 2020. The time series of Normalized Difference Vegetation Index (NDVI) was derived at annual scale to assess changes in the vegetation cover. New hydrological insights for the region The modeling revealed that an additional 5% of the rainfall depth was being recharged into the groundwater. In addition, the additional soil moisture was allowing natural grass cover to develop, which could be used by the local community as pastureland. These twin benefits that the local communities are realizing could be scaled up beyond Dudu, to India, and worldwide, as many regions have barren land that is slightly sloping, together with permeable soils, which are the only conditions for the construction of Chaukas. These Chauka systems have helped in sustainable water resources management in these water-stressed regions and the additional livelihood support through developed pastures for animal husbandry.

The effects of spatial variability and human factors on soil lead to complex soil hydraulic properties. In areas with highly variable water levels, it is impossible to use analytic expressions to accurately quantify and describe the process of moisture transport. In this study, the HYDRUS software package was used to calculate and simulate soil moisture transport under variable water levels by analyzing soil and underground water as an integrated system, and conducting in-situ monitoring tests on a large indoor soil trough. The results showed that: (1) the initial model verification achieved by adjusting the groundwater level revealed that when the groundwater dropped, the soil moisture in the vadose zone transitioned from balanced to unbalanced to balanced again; (2) the values and development trends of the negative pressure and water content of the soil as calculated by the model using adjusted parameters were consistent with those of the measured result, which indicated that the moisture transport model established in the GSPAC system was credible; and (3) the model established by the HYDRUS software package was able to effectively predict the soil moisture transport and infiltration dynamics.

Drip irrigation is one of the conservative irrigation techniques since it implies supplying water directly on the soil through the emitter; it can supply water and fertilizer directly into the root zone. An equation to estimate the wetted area in unsaturated soil is taking into calculating the water absorption by roots is simulated numerically using HYDRUS (2D/3D) software. In this paper, HYDRUS comprises analytical types of the estimate of different soil hydraulic properties. Used one soil type, sandy loam, with three types of crops; (corn, tomato, and sweet sorghum), different drip discharge, different initial soil moisture content was assumed, and different time durations. The relative error for the different hydraulic soil models was calculated and was compared with the model of Brooks and Corey, 1964. There was good agreement compared with different models. The Root Mean Square Error (RMSE) was (0.23) cm, while the relative error (- 1%) and (1) for modeling efficiency (EF) for wetted radius, but wetted depth was RMSE (0.99) cm, and the relative error was (4.5%), and EF was (1).

امروزه فعالیت­های انسانی در بخش کشاورزی به­خصوص در نواحی خشک و نیمه­خشک برروی چرخه و انتقال آب سطحی و زیرزمینی تاثیر به‌سزایی داشته است. از این­رو، بررسی وضعیت منابع آب زیرزمینی دارای اهمیت است. تخمین‌های مناسب و قابل‌اعتماد تغذیه ناشی از آبیاری بر آب زیرزمینی می­تواند در این امر موثر باشد. به‌منظور بررسی تأثیر آبیاری بر تغذیه آبخوان، یک مزرعه گندم، دو مزرعه جو و سه مزرعه چغندرقند در شهرستان میاندوآب و دو مزرعه گندم در شهرستان مهاباد در حوضه دریاچه ارومیه تحت مدیریت کشاورزان انتخاب شدند. شبیه‌سازی نفوذ با استفاده از مدل HYDRUS-1D در طول دوره رشد محصولات مذکور انجام شد. با پایش رطوبت خاک در این مزارع، مدل با رطوبت‌های خاک اندازه‌گیری شده از طریق حل معکوس، واسنجی و صحت­سنجی شد. دقت مدل بعد از انجام مراحل واسنجی و صحت­سنجی در تخمین جریان آب در داخل خاک مناسب بود. مقادیر ضریب تعیین و خطای جذر میانگین در مرحله واسنجی به ترتیب بین 6/0 تا 85/0 و 17/0 تا 033/0 به دست آمد. ضریب تعیین و خطای جذر میانگین مربعات در مرحله صحت‌سنجی نیز به ترتیب بین 62/0 تا 88/0 و 002/0 تا 023/0 () به دست آمد. پس از واسنجی مدل، تغییرات رطوبت در اعماق مختلف خاک تا سطح آبخوان توسط مدل شبیه‌سازی شد. پیشروی رطوبت در عمق خاک از عمق 7/0 تا 7/4 توسط مدل برآورد شد. آب آبیاری سبب تغذیه آب زیرزمینی در مزارع مورد مطالعه شد که این میزان تغذیه در اثر آبیاری و بارندگی، بسته به نوع خاک، نوع کشت و مدیریت آبیاری در مزارع مختلف متفاوت بود. بیشترین تغذیه در مزرعه H3 با خاک لوم رسی شنی به مقدار 221 میلی متر از 789 میلی متر مجموع آبیاری و بارندگی (28 درصد) در طول فصل کشت گیاه جو بدست آمد.

An explicit finite-difference routine was developed to simulate the three-dimensional water movement from a trickle irrigation source by direct numerical integration of the Richards equation. Validation of the code was performed, on the one hand, by comparison with existing analytical solutions, and, on the other hand, with the HYDRUS 2D/3D software package to check different conditions further than assumed analytical simplifications. In the simulations performed, the routine showed an accurate and stable behavior. Additionally, it is flexible to define different boundary conditions. Furthermore, some specific studies performed with this routine are presented to illustrate the applications of this tool. It is shown that the code is able to reproduce water infiltration features such as redistribution, unsteady surface puddle area, and time-dependent overpressure around a buried emitter, which are phenomena of interest that are difficult to simulate with other software.

Conducting field experiments to determine an optimal strategy for managing water consumption in paddy fields is quite time-consuming and expensive. This study applied HYDRUS-2D model to simulate fluctuations in water level and nitrate transfer over the 2 years of 2013 and 2014 at Rice Research Institute of Iran (Rasht). To monitor water-level fluctuations, a piezometer was installed in the plot. Three irrigation management regimes were considered: first, permanent water flooding or irrigating by as much as 1.3 times the amount of evaporation from the evaporation pan (I1); second, applying irrigation treatment by one time the amount of evaporation from the evaporation pan (I2); third, irrigating by 0.7 times the amount of evaporation from the evaporation pan (I3) from the transplanting date to the end of irrigation period (10 days before harvest). Two fertilizing treatments were considered, i.e., C1 = 60 kg N ha−1 and C2 = 60 kg N ha−1 + 5000 kg compost ha−1 equal to 160 kg N ha−1. After model run, observed and simulated values were compared using EF (efficiency factor), RMSE (root-mean-squared error), and nRMSE (normalized root-mean-squared error) indices. The results of EF, RMSE, and nRMSE with respect to water-level changes at the calibration stage were 0.94, 5.39 cm, and 7.6%, respectively. At the validation stage, the results of EF, RMSE, and nRMSE were 0.96, 2.25 cm, and 3.2%, respectively. The nRMSE index showed the model's excellent performance in simulating water-level changes. In the case of nitrate transfer, at the calibration stage, the EF values at the two fertilizer levels of C1 and C2 were 0.60 and 0.85, and nRMSE values were 27 and 9.97%, respectively. At the validation stage, the EF values at the two levels of C1 and C2 were 0.60 and 0.99, and nRMSE values were 13.7 and 1.3%, respectively. Based on the values of nRMSE index, the performance of the model in simulating nitrate transfer was shown to vary in the medium-to-excellent class. Overall, the simulation results showed that the HYDRUS-2D model exhibited an appropriate ability to simulate water movement and nitrate transport either from chemical or compost sources; therefore, it can be used for irrigation and fertilizer management in the case of paddy fields to analyze different scenarios.

Intraocular implants, specifically those used in the treatment of glaucoma, are each associated with various implant related risks and complications of which surgeons placing these devices must be aware. Here we present a case of uveitis-glaucoma-hyphema (UGH) syndrome associated with the Hydrus Microstent.

PFOA and PFOS are widely found PFAS components in Dutch topsoils. PFOA was emitted to the atmosphere during 1970-2012 from a fluoropolymers factory, and was deposited mainly within a radius of 50 km. For the first time, detailed concentration-depth profiles of PFOA and PFOS were measured in undisturbed soils downwind of the factory. Three locations were selected with about 3 meters of sand soil and free infiltration of rain. An adjacent peat soil was selected for comparison. In the sand soils, concentration-depth profiles of PFOA showed a distinct bell-shaped pattern with the highest contents at 0.2-0.5 m below surface, and lower contents both at the surface and at further depth (up to 3.5 m below surface). This observation indicates that the highest atmospheric deposition has passed, and that PFOA gradually migrates towards groundwater. Concentrations of PFOS are highest near the surface and reach the detection limit at 1 m below surface, suggesting that its downward migration occurs much slower. HYDRUS was used to model PFAS transport in the vadose zone assuming steady-state infiltration. The PFOA depth profiles in the sand soils can be described assuming plausible historic, atmospheric emission of PFOA from the factory and Koc values within the literature range. However, the retention observed must be attributed to linear partitioning between water and both soil organic matter and the air-water interface. Somewhat stronger retention holds for PFOS, but PFOS cannot originate from the factory in the extent found. An alternative explanation is historic, rather parallel emissions from nearby sources such as waste incinerators. Based on measurements and modelling, this study illustrates that PFOA, and to a lesser extent PFOS, should not be treated as immobile contaminants in topsoil as is currently the case in Dutch soil policy, but rather as mobile contaminants of which the legacy amounts in soil will pollute groundwater for many decades.

This study aims to explain complex vadose zone hydrology of fine-textured (gley) agricultural soils influenced by a shallow and dynamic groundwater (GW) levels. The field site was located in the Biđ field (Eastern Croatia), where a detailed soil survey was performed. The simulations included a three-year period (2016 - 2018) at four locations. Soil hydraulic parameters (SHP) were estimated based on variables determined in the laboratory, while soil water flow was monitored using in-field zero-tension lysimeters. Piezometers were installed and used to monitor daily oscillations of groundwater levels (average depth to GW 2.2 m), while data from nearby Sava River was monitored. Unsaturated flow and water regime assessment was performed using HYDRUS-1D numerical modeling. Additional SHP optimization of van Genuchten-Mualem parameters (α and n) was performed using Shuffled Complex Evolution algorithm (SCE). The autocorrelation analysis was used to detect patterns in the precipitation, GW, and river level time series, while the Mutual Information (MI) was used to estimate the codependence of the processes in unsaturated zone and the main hydrological events. The model successfully (R2 0.72 – 0.94) reproduced measured lysimeters outflows. The outflows from lysimeters were connected to precipitation patterns, transpiration intensity, and soil moisture content influenced by the shallow water table. Comparable MI values obtained for precipitation, GW, and river level suggest a concurrent role of these parameters in the unsaturated flow dynamics. The relationship between upward flux/water storage change into the domain, and transpiration/growth stages, suggests a strong connection between the water fluxes and the root water uptake. Results confirm the importance of GW for the agricultural production due to the major influence on upper soil layer moisture.

Aim of study: To investigate the monitoring strategies that let us to build effective models able to best estimate water contents, θ and pressure heads, h with the least amount of data. Area of study: Field data was acquired in an experimental plot at Bahía Blanca (Argentina). Material and methods: Field data of θ(t), h(t) for six soil depth were used to optimize the SHP (θr, θs, α, n and Ks) by inverse modeling with HYDRUS 1D. Several scenarios of available data from θ(t) and h(t) were considered: (1) six monitoring depths (6-MD); (2) five monitoring depths (5-MD); (3) four monitoring depths (4-MD). Model accuracy was assessed by comparing the measured and predicted θ and h for each monitoring strategy. Additionally, field measured SHP with independent methods were compared to inversely optimized SHP. Main results: The best fit between predicted and observed θ and h was achieved with the 6-MD strategy. Nevertheless, deterioration of statistics EF and rRMSE in the 5-MD or 4-MD schemes were lower than 10%, depending on the location of the missing data. The observation points that had less importance in parameter prediction corresponded to the intermediate vadose zone and to the deeper layers. The proposed strategies presented a better performance than field measured SHP to reproduce soil water retention curves for each layer of the soil profile. Research highlights: By reducing the number of vertical observations in the profile without harming the final SHP estimation, the resources needed in data monitoring strategies can be greatly enhanced. Universidad Nacional del Sur (UNS) 24/H145; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).

The paper presents the results of a 24-month-long observation comparing the effectiveness and safety of two micro-invasive glaucoma surgery (MIGS) devices: Hydrus Microstent and iStent Trabecular Bypass in combination with cataract phacoemulsification in the treatment of open-angle glaucoma. We also analyzed the impact of preoperative factors on achieving surgical success in both surgical methods. The prospective, comparative, non-randomized study included 65 glaucoma surgeries. In 35 patients (53.8%), an iStent implant procedure was performed, while 30 patients (46.2%) underwent a Hydrus implant procedure. The demographic data was similar in both treatment groups. At 24 months after surgery, the mean IOP in the iStent group was 15.9 ± 3.0 mmHg and in the Hydrus group 16.2 ± 1.8 mmHg. The difference between the mean iStent vs Hydrus after two years of treatment was −0.3 (p = 0.683). At the 24 month follow-up, the average change in the number of antiglaucoma medications used was 71.7% in the iStent group and 79.6% in the Hydrus group. The difference in mean percentage change between groups was 7.9% in favor of Hydrus. Patients under the age of 70 may benefit from a greater risk reduction in the Hydrus group (HR = 0.81), while those over the age of 70 may benefit from a risk reduction in the iStent group (HR = 1.33). IOP cases with >18 mmHg before the surgery have a better chance of surgical success with the Hydrus method (HR = 0.28), and with IOP < 18 mmHg in the iStent group (HR = 1.93). Cases with more drugs (≥3 drugs) are more favorable in the Hydrus group (HR = 0.23), while those with a maximum of two drugs have a better prognosis in the iStent group (HR = 2.23). The most common postoperative complication was the presence of erythrocytes in the anterior chamber (AC), found in 40.0% of operated eyes in the Hydrus group. The profile of observed complications and significant improvement in visual acuity allows us to consider both implants as a safe way of treating patients with early or moderate glaucoma and co-existing cataracts.

Pseudoglej je drugo najzastupljenije tlo unutar agroekosustava, a karakterizira ga slabije propusni potpovršinski horizont koji utječe na periodičko stagniranje oborinske vode i restrikcije u rastu korijena. S obzirom na prisutne klimatske promjene, izrazito je važno pratiti režim vlažnosti tla kako bi se na vrijeme reagiralo i umanjile štetne posljedice. Cilj ove disertacije bio je utvrditi svojstva rigolanog tla iz pesudogleja obronačnog u uvjetima uzgoja vinograda te utjecaj svojstava tla i proraštenosti tla korijenom na tok i retenciju vode u tlu. TDR senzori za praćenje režima vlažnosti postavljeni su na pet pozicija obronka u površinski (Ap) i potpovršinski (Bg) horizont te u red i međuredni dio vinograda. Na istim pozicijama utvrđena su fizikalna, kemijska i hidraulička svojstva tla. Rezultati analiza fizikalnih svojstava tla pokazuju izrazitu heterogenost s obzirom na položaj na obronku. Tako je utvrđen signifikantan utjecaj pozicije na sadržaj pijeska, praha, gline, humusa, volumne gustoće, kapaciteta tla za vodu, kapaciteta tla za zrak, i ukupnog poroziteta (za sve P < 0,0001). Isto tako utvrđene su značajne razlike u fizikalnim svojstvima između reda i međurednog prostora vinograda, za oba horizonta. Tijekom istraživanja uočene su i značajne razlike u volumetrijskom sadržaju vlage u tlu ovisno o poziciji na obronku (P < 0,0001) te između reda i međurednog prostora vinograda (P < 0,0001). Prosječno najveće vrijednosti volumetrijskog sadržaja vlage u tlu zabilježene su na višim pozicijama obronka (tj., P1 i P2). Navedeno bi moglo biti povezano sa povećanim sadržajem gline na istim pozicijama. Razlike u sadržaju vlage između reda i međurednog prostora pripisane su razlikama u korijenu kultura (vinova loza i trava) koje koriste različite količine vode tijekom vegetacije. HYDRUS 1D model korišten za simuliranje toka i retencije vode na istraživanoj parceli kalibriran je na temelju vrijednosti o volumetrijskom sadržaju vlage u tlu izmjerenim pomoću TDR senzora. Hidraulički parametri korišteni kao ulazni podaci u modelu prilikom simulacija procijenjeni su na tri načina, i to temeljem (i) evapotranspiracijske metode pomoću HYPROP i WP4C uređaja, (ii) „tipa pet“ pedotransfernih funkcija u ROSETTA softveru, te (iii) preko inverznog modeliranja u HYDRUS 1D modelu. Neke simulacije sa hidrauličkim parametrima iz HYPROP i ROSETTA softvera bile su nestabilne (model nije konvergirao). Korištenjem inverznog pristupa, sve simulacije bile su stabilne i prokazale su relativno zadovoljavajuće rezultate (RMSE = 0,004 do 0,084 cm3 cm-3). Hidraulički parametri tla procijenjeni inverznim modeliranjem dalje su korišteni kao ulazni parametri za simulacije u HYDRUS 2D/3D modelu kojim se simulirao tok i retencija vode na cijelom istraživanom obronku, te u tri izmijenjena klimatska scenarija. Za još uspješnije korištenje modela, preporuča se posebnu pažnju posvetiti ulaznim parametrima kao što su hidrauličke značajke tla i parametri uzgajane kulture. Pseudogley is the second most widespread soil found in the agroecosystems of Croatia (307,453.2 ha). It is characterized by the presence of a less permeable subsurface horizon that affects the occasional (longer or shorter) occurrence of excessive saturation of the upper zone of the profile and have restrictions on root growth. According to FAO (2014), the soil profile of the natural pseudogley profile is designated as A-Eg-Bg-C, while according to the Soil Classification of Croatia as A-E / S-B / S-C (Husnjak, 2014). Since pseudogley as a soil type develops in regions that are in terms of relief and climate suitable for agriculture, a significant part of pseudogley is deeply ploughed for growing permanent crops. Deep ploughing resulted in mixing of the humus-accumulative with the eluvial-pseudogley and the upper part of the illuvial-pseudogley horizon, thus forming an anthropogenic horizon. Such pseudogleys are referred to as Ap-Bg-Cg (FAO, 2014), or P-B / S-C / S (Husnjak, 2014). Soil moisture distribution and its spatial and temporal variability affect plant growth and development. Due to climate change, it is very important to develop models that will predict their impact on soil, but also on crop production. Given the above, it is extremely important to continuously monitor the water content in the soil with the aim of irrigation scheduling in order to mitigate the effects of drought. Measuring the soil moisture regime requires a lot of field work, is time consuming and expensive. With the development of computer technology, many numerical models have been developed that, based on pedotransfer functions and/or measured hydraulic parameters, can solve water movement in the (un)saturated zone of the soil. Based on the above stated, the following research hypotheses were set: (i) in the investigated agroecological conditions during the autumn/winter period there is no occurrence of prolonged excessive soil saturation (over 120 days per year) characteristic for pseudogley, (ii) soil moisture regime and water flows are affected by relief or position on the slope and hydraulic parameters of the subsurface horizon, and vine roots, (iii) using a numerical model one can reliably determine the flow and retention of water in the studied agroecological conditions. The research was conducted over two years (2019, 2020) in Jastrebarsko (45º41'22 "N; 15º38'22" E). The investigated plot is located on the slope with the southeastern exposure, it is 90 m long and has a slope of 14%. A vineyard (Traminac cv.) was planted on the investigated plot in 1999, where the planting distance in the row was 1.0 m, and between the rows 2.5 m. The rows are oriented down the slope, and the interrow area is planted with grass to limit the erosion. On the investigated plot, five pedological profiles were dug, to a depth of 110 cm, which were equidistant from each other (18 m) along the entire length of the slope. From the pedological profiles, disturbed samples and undisturbed soil cores were taken (100 and 250 cm3 volume cylinders). Samples were taken in a row and in the inter-row part of the vineyard. After sampling, TDR sensors were installed in each of the five profiles for monitoring of soil moisture regime at 30 and 90 cm deep in a row and in the inter-row part of the vineyard. Also, at 30 cm in a row and in the inter-row space, tensiometers were placed to monitor soil water potential, after which the profiles were buried again. In addition to monitoring the soil moisture regime (TDR sensors and/or tensiometers), the level of water stress in the vine can be determined by measuring the leaf water potential of the vine. Therefore, during 2020, at three slope positions (top, middle and bottom of the slope), the water potential on the vine was measured in order to determine the correlation between the soil water potential and the vine (leaf) water potential. The results showed that no significant correlation was observed between the water potential of the soil and the vine. However, the correlation between soil water potential and relative humidity was positive and strong (r = 0.56 - 0.62). Based on standard laboratory analyzes, the basic physical (soil texture, bulk density, differential and total porosity), chemical (pH and humus content) and hydraulic properties of the soil (θs, θr, α, n, Ks) were determined. The results of the analyzes indicate a pronounced heterogeneity of particle size distribution, bulk density, total porosity with respect to the position on the slope, and pH and humus (for all values of P < 0.0001). Significant differences in soil properties between row and inter-row space of vineyards were also found. During the research, significant differences in soil moisture were observed depending on the position on the slope (P < 0.0001), as well as differences between the row and the inter-row space of the vineyard (P < 0.0001). Thus, the highest values of soil moisture content during the investigated period were observed at the upper P1 and P2 positions of the slope. This could be related with increased clay content at these positions. On average, the highest moisture content in the soil during the investigated period was observed in the row for the surface (Ap) and in the interrow for the subsurface (Bg) horizon. TDR sensors determined that excessive saturation was present in the middle of the slope (P3 position) throughout the study period. This could be related to increased clay content, at P1 and P2 slope positions which could affect the occurrence of subsurface lateral flow. However, although saturation conditions prevailed at the P3 position throughout the investigated period, the relative water content in the soil was lower compared to the positions above. This could be related to the increased sand content in the Bg horizon at P3 compared to other positions and to the fact that the sand has a low water retention capacity. In addition to measuring the soil moisture regime, the HYDRUS 1D and HYDRUS2D / 3D model was used for its assessment. The hydraulic parameters used in the model were estimated in three ways: (i) by evapotranspiration method based on HYPROP and WP4C systems, (ii) by “type five” estimation of pedotransfer functions in ROSETTA software, and (iii) by inverse simulation using HYDRUS 1D program. In the first step, the hydraulic parameters (θs, θr, α, Ks, n and l) of the soil obtained through the HYPROP and WP4C systems were used, by applying which the HYDRUS 1D model was unstable, i.e., did not converge in most cases. In the second step, the estimated hydraulic parameters also did not give satisfactory results in HYDRUS 1D simulations, so in the third step they were estimated by inverse modeling. Inverse modeling was performed on the calibration period (from 13.9. to 12.10.2019) Which was chosen because it had the equal time of wet and dry days. Values of R2 were generally above 0.90 excluding P1 and P3 positions in a row in which R2 was, respectively, R2 = 0.645 and R2 = 0.882. RMSE values in most positions are generally less than 0.03 cm3 cm-3, except for P1 position in the row where the RMSE was 0.05 cm3 cm-3. The inverse simulation showed the most reliable (but still not ideal) results of the assessment of hydraulic parameters. However, in the absence of insufficiently good measurements (HYPROP) and estimation of hydraulic parameters (ROSETTA), hydraulic parameters estimated through inverse modeling were further used in the work. After calibration and validation in the HYDRUS 1D program, the hydraulic parameters estimated by inverse modeling were further used as input parameters for simulations of water flow and retention on the entire slope using the HYDRUS 2D/3D program. With respect to climate change in the HYDRUS 2D/3D program, three climate scenarios were simulated (according to IPCC, 2014) (i). mild (predicting a 1.5ºC temperature rise) (ii) medium predicting a 2.5ºC temperature rise (iii) extreme predicting a 3.5ºC temperature rise. Also, IPCC, 2014 predicts that precipitation in the winter months will increase, while longer periods of drought will prevail in the summer months. Although no significant differences were found between the simulated climate scenarios, it can be concluded that the HYDRUS model after calibration and validation can be successfully used to predict different climate scenarios. For more successful use of the model and based on the research results obtained in this dissertation, it is recommended during modeling to pay attention to proper soil hydraulic properties determination, since they have the largest impact on the simulation results. Furthermore, for simulations over longer time periods, the hydraulic properties of the soil should be determined on several occasions with respect to their temporal variability which is pronounced in intensively managed arable soils. In addition to the hydraulic properties of the soil, the data on the crop (eng. leaf area index, root depth) have a significant impact on the simulation results and should therefore be given additional attention.

Drywells (DWs) and infiltration basins (IBs) are widely used as managed aquifer recharge (MAR) devices to capture stormwater runoff and recharge groundwater. However, no published research has compared the performance of these two engineered systems under shared conditions. Numerical experiments were conducted on an idealized 2D‐axisymmetric domain using the HYDRUS (2D/3D) software to systematically study the performance of a circular IB design (diameter and area) and partially penetrating DW (38 m length with water table > 60 m). The effects of subsurface heterogeneity on infiltration, recharge, and storage from the DW and IB under constant head conditions were investigated. The mean cumulative infiltration (μI) and recharge (μR) volumes increased, and the arrival time of recharge decreased with the IB area. Values of μI were higher for a 70 m diameter IB than an DW, whereas the value of μR was higher for a DW after 1-year of a constant head simulation under selected subsurface heterogeneity conditions. A comparison between mean μI, μR, and mean vadose zone storage (μS) values for all DW and IB stochastic simulations (70 for each MAR scenario) under steady-state conditions demonstrated that five DWs can replace a 70 m diameter IB to achieve significantly higher infiltration and recharge over 20 years of operation. Additional numerical experiments were conducted to study the influence of a shallow clay layer by considering an IB, DW, and a DW integrated into an IB. The presence of such a low permeable layer delayed groundwater recharge from an IB. In contrast, a DW can penetrate tight clay layers and release water below them and facilitate rapid infiltration and recharge. The potential benefits of a DW compared to an IB include a smaller footprint, the potential for pre-treatments to remove contaminants, less evaporation, less mobilization of in-situ contaminants, and potentially lower maintenance costs. Besides, this study demonstrates that combining both IB and DW helps to get the best out of both MAR techniques.

This study investigated the ability of a HYDRUS 1D model for predicting the vertical distribution of potassium iodine (200 ppm) in soil columns after amendment with five different common remediation materials (gypsum, lime, fly ash, charcoal and sawdust) at a rate of 2.5% (w/w), relative to an unamended control soil. Results shows that relative to the unamended soil, iodine leaching was decreased by all amendments but that the magnitude of the decreases varied with the soil amendment applied. Iodine content was highest in the upper layer of the soil columns and decreased progressively with soil depth. The model was evaluated via comparison of the model simulated values with measured values from the soil column studies. The results showed that the HYDRUS 1D model efficiency was near to 1, indicating that the stimulated results were near to the measured values. Therefore, this study showed that iodine leaching through a soil could be ascertained well using a HYDRUS 1D model. The model over predicted iodine leaching, resulting to a weak correspondence between the simulated and the measured results for iodine leaching. This suggests that the HYDRUS-1D model does not explain accurately different organic and inorganic amended soil and the preferential flow that occurs in these columns. This may be due to the fact that Freundlich isotherm, which is part of the transport equations, does not sufficiently describe the mechanism of iodine adsorption onto the soil particles. This study would help to select amendments for an effective management strategy to reduce exogenous iodine losses from agro-ecosystems. This would also improve understanding of iodine transport in soil profile.

Tok vode u tlima ključan je proces koji utječe na njenu količinu i kvalitetu. S obzirom da je transport onečišćivača u tlu usko povezan s kretanjem vode vrlo je važno na pravilan način procijeniti navedene procese u stvarnim (poljskim) uvjetima. Cilj ovog rada je kalibrirati i validirati model toka vode u nesaturiranoj zoni tla na temelju podataka o količini vode u tlu i vodnog potencijala tla. Istraživanje je provedeno na tri lokacije u drugoj zoni vodozaštite grada Zagreba. Terenskim opažanjima (TDR tehnologija) i laboratorijskim analizama (HYPROP-FIT) eksperimentalno su određeni hidraulički parametri tla koji su prvi korak u određivanju toka vode. Za primjenu numeričkih simulacija korišten je HYDRUS-1D program kojim je simulirana volumna količina vode u tlu i vodni potencijal. Radom se izvršila kalibracija modela toka vode pri čemu su korištene optimizirane, inverzno dobivene vrijednosti hidrauličkih parametara. Rezultati istraživanja varirali su ovisno o hidrauličkim parametrima tla te klimatskim parametrima (temperatura, oborine i evapotranspiracija). Statističkom analizom podataka potvrđeno je da je model uspješno validiran i kalibriran. Water flow in soils is a key process that affects its quantity and quality. Given that the transport of pollutants in the soil is closely related to the water flow, it is very important to properly assess these processes in real (field) conditions. The aim of this paper is to calibrate and validate the water flow model in the unsaturated soil zone based on soil water content and pressure head data. The research was conducted at three locations in the second water protection zone of Zagreb city. With the field observations (TDR technology) and laboratory analyzes (HYPROP-FIT) we experimentally determined the hydraulic parameters of the soil, which is the first step in determining the water flow. HYDRUS-1D program was used for the numerical simulations, which determined soil water content and pressure head. The calibration of the water flow model was performed using optimized, inversely obtained values of hydraulic parameters. The results of the research varied depending on soil hydraulic properties and climatic parameters (temperature, precipitation and evapotranspiration). Statistical analysis of the data confirmed that the model was successfully validated and calibrated.

New water-conserving irrigation technologies are vital in arid countries. We investigated the effects of (i) soil substrates made of Smart Capillary Barrier Wick (SCB-W), consisting of silt loam blocks surrounded by sand-sheathes and irrigated with a sand wick cylinder (WC) as compared to a control (homogenous soil irrigated by the same wick system, HW), (ii) WC diameters (2.54 cm vs. 1.27 cm), and (iii) 2-cm sand mulch layer on soil–water dynamics during wetting–drying cycles. Field experiments with pots and HYDRUS (2D/3D) modeling were performed in two consecutive phases (with and without sand mulch). Analysis of variance at p

Subterranean termites (Odontotermes formosanus Shiraki) that build nests in the soil matrices of earth embankments may adversely affect the stability of these structures in paddy farming regions of southern China. An adult termite nest comprises a primary chamber, fungus gardens, passageways, and other shelter tubes. These porous architectures enable high hydraulic conductivity and rapid groundwater flow. In this study, we performed a field survey to characterize these termite nest architectures and proposed a simulation method that estimates seepage and associated stability in termite-infested earth embankments. Three types of nest architectures—straight, siphon, and string—were investigated in situ. Groundwater flow and its relationship with earth embankment stability were analyzed using a numerical model based on the two-dimensional Richards equation in the HYDRUS software package. Results indicated that the presence of termite nests affected seepage zone geometry and substantially affected its phreatic line, seepage flux, and global and local stabilities of the earth embankment. In the cases examined here, the presence of termite nests resulted in a maximum factor of safety reduction of 17% along the downstream slope. The local instability zones of earth embankment, resulting from clogged termite nest passageways along the downstream slope, were also assessed.

In the current study, the temporal distribution of both soil water and soil NO3–N under several conservation agriculture (CA) practices during the wheat crop growth were characterized by HYDRUS-2D model. Treatments comprised of conventional tillage (CT), permanent broad beds (PBB), zero tillage (ZT), PBB with residue (PBB+R) and ZT with residue (ZT+R). Hydraulic inputs of the model, comprising the measured value of Kfs, α and n, obtained as the output of Rosetta Lite model were optimized through inverse modeling. Model predicted the daily change in soil water content (SWC) of the profile during the simulated period (62–91 DAS) with good accuracy (R2 = 0.75; root mean squared error (RMSE) = 0.038). In general, soil water balance simulated from the model showed 50% lower cumulative drainage, 50% higher cumulative transpiration along with higher soil water retention, in PBB+R than CT. Reported values of the first-order rate constants, signify nitrification of urea to NH4–N (μa) (day−1) nitrification of NH4–N to NO3–N (μn) (day−1) and the distribution coefficient of urea (Kd−in cm3 mg−1) were optimized through inverse modeling. Later they were used as solute transport reaction input parameters of the model, to predict the daily change in NO3–N of the profile with better accuracy (R2 = 0.83; RMSE = 4.62). Since NH4–N disappears fast, it could not be measured frequently. Therefore, not enough data could be generated for their use in the calibration and validation of the model. Results of simulation of daily NO3–N concentration indicated a higher concentration of NO3–N in the surface layer and its leaching losses beyond the root zone were relatively lesser in PBB+R, than CT, which resulted in less contamination of the belowground water. Thus, the study clearly recommended PBB+R to be adopted for wheat cultivation in maize–wheat cropping system, as it enhances the water and nitrogen availability in the root zone and reduce their losses beyond the root zone.

Determining the soil water content (SWC) in a soil profile is very important task for agriculture and also for a wider ecological context. The spatial and temporal variability of SWC is a elementary issue for agricultural practice, irrigation management, or landscape management globally. Various methods are used for obtaining the SWC data. Every method has some advantages and also disadvantages. Many of them are focused only on one dimension but modern precise agriculture needs the information about SWC in spatial scale. This study is focused on the spatial scale analysis of SWC in the Nitra river catchment for years 2013 and 2014. The HYDRUS 1D hydrological model and GIS tools were used for the creation maps of SWC. Combination of the measured and simulated data was used for the creation of the unique spatial maps of soil moisture in 0-30 and 30-60 cm soil horizons. Validation of our method shows trustworthy results. Soil water storage and fulfillment of maximum soil water storage were analysed with using the created maps.

Subsurface drip irrigation is one of the modern irrigation techniques that assist to control applied water by providing water to plant roots by drippers. Numerical simulation by using HYDRUS (2D/3D) was used to develop a formulas for estimating wetted area from subsurface drip irrigation together with water uptake by roots. In this study, two soil types, namely sand and sandy clay loam, were used with two types of crops, (tomatoes and onions). Different values of initial moisture content of soil, drip depth, and drip discharge were used in the simulation. The soil wetting patterns were analyzed each half an hour for three hours of irrigation time, and five initial soil moisture contents and different flow rates. To verify the results gained by applying HYDRUS (2D/3D) a field experiment was carried out to measure the wetted width and compare measured values with simulated values. Formulas for wetted width and depth were developed. The performance of the model was evaluated by comparing the predicted results with those obtained from field experiments. The modeling efficiency was greater than 98% and the root mean square error did not exceed 1.68 cm for both soils with good agreement.

Simulation of water and salt transfer in soil is very effective in managing optimal water and fertilizer use in the field. In this study, the HYDRUS-1D model was used to simulate the transfer of water and bromide in a laboratory column of soil with clay loam texture. Soil hydraulic parameters (including air entry point) α, (saturated hydraulic conductivity) ks, (residual moisture content) θr (saturation moisture content) θs, (pore and particle joint parameter) l (parameter of moisture curve shape) n through measurement and using Retc software was obtained Solubility transfer parameters including difiusion coefficient and actual velocity were estimated using soil hydraulic parameters and bromide concentration data by reverse modeling method. According to the target coefficients, the sensitivity analysis of the physical model was performed .The results showed that the correlation coefficient of observation and simulation bromide concentration in optimal mode was 0.84%. accordingly, the diffusion coefficient was estimated to be 4.9 cm. based on the results of the sensitivity analysis, the saturation hydraulic conductivity had the greatest effect on the variation of this parameter, so that the amount sensitivity coefficient of this parameter was 2.64 The RMSE coefficient with a value of 0.04 was the lowest and ME coefficient with the value of -0.0001 had the most parameter variations.

Spatio‐temporal variations of nitrate‐nitrogen (NO3-‐N) leaching is driven by both soil hydrology and biogeochemistry. However, the widely used soil hydrology and biogeochemistry models have their weaknesses in simulating soil N cycling and soil water movement processes, respectively. In this study, we proposed an alternative approach by simply combining the HYDRUS‐3D and DNDC models to investigate the spatio‐temporal variations of NO3-‐N leaching on a representative tea garden hillslope in Taihu Lake Basin, China. Results showed that the soil hydrology and N cycle were well simulated by HYDRUS‐3D and DNDC models, respectively. Based on the leaching equation, the soil water flux simulated by HYDRUS‐3D and soil NO3-‐N content simulated by DNDC were combined to calculate the leachate NO3-‐N concentrations with good accuracy. The accumulative NO3-‐N leaching flux during the simulation year was 71.7 kg N ha⁻¹, with remarkable spatio‐temporal variations on this hillslope. Hot spots of NO3-‐N leaching were observed in blocks 24, 27, 31, 34, 37, and 40 with accumulative leaching fluxes > 82.0 kg N ha⁻¹ y⁻¹. The spatial variation of NO3-‐N leaching was mainly controlled by soil texture and soil hydraulic properties. Hot moments of NO3-‐N leaching were observed after the applications of spring fertilizer (16 March) and basal fertilizer (30 October). The temporal variation of NO3-‐N leaching was mainly controlled by precipitation and the spring fertilization. Methods and findings of this study will be benefit for the risk assessment of non‐point source N loss and the precise agricultural management.

The saturated hydraulic conductivity ( K s ) is considered to be one of the main soil hydraulic properties to simulate water transport in the vadose zone, yet it is notoriously difficult to assess due to its large field-scale variability and sensitivity to preferential flow paths. With the increasing availability of convenient methods to measure the unsaturated hydraulic conductivity ( K u ), the additional value of measuring K s could be questioned. This study investigates the relevance of measuring K s in two ways. Firstly, a sensitivity analysis was performed to evaluate which part of the hydraulic conductivity curve impacts the simulation of unsaturated water transport most. It was found that hydraulic conductivity curve between −10 cm and −1000 cm matric head was affecting the simulation more than at saturation. Secondly, a functional evaluation was performed by simulating water flow in six test fields according to three scenarios, in which the hydraulic properties were determined with the measured K s and/or K u . The simulation of saturation degree at three depths was the least accurate in the scenario where only K s was measured. Remarkably, the most accurate simulation was found in the scenario with only the measured K u . According to these results, measuring K u would be of greater importance than measuring K s for the simulation of water flow in the vadose zone.

The main approach for designing vertical flow (VF) treatment wetlands is based on areal requirements ranging from 2 to 4 m2 per person equivalent (PE). Other design parameters are the granularity of the filter material, filter depth, hydraulic and organic loading rates, loading intervals, amount of single doses as well as the number of openings in the distribution pipes. The influence of these parameters is investigated by running simulations using the HYDRUS Wetland Module for three VF wetlands with different granularity of the filter material (0.06–4 mm, 1–4 mm, and 4–8 mm, respectively). For each VF wetland, simulations are carried out at different temperatures for different organic loading rates, loading intervals and number of distribution points. Using coarser filter material results in reduced removal of pollutants and higher effluent concentrations if VF wetlands are operated under the same conditions. However, the treatment efficiency can be increased by applying more loadings and/or a higher density of the distribution network. For finer filter material, longer loading intervals are suggested to guarantee sufficient aeration of the VF filter between successive loadings.

Subsurface drip irrigation is increasingly being used for sugarcane production in Southeast Brazil in attempts to conserve water, especially after extreme droughts in 2014 and 2015. Correct design of a subsurface drip system is essential to provide information about water and solutes dynamics in the subsurface, leading to possible water savings. While field investigations demand much time and financial resources, numerical models can also provide much information about expected water and solute distributions in the soil profile. The objective of this study was to use HYDRUS-2D for simulations of water and potassium movement in containers packed with a subsurface drip-irrigated tropical soil cultivated with sugarcane and comparing simulated and observed data through statistical parameters. Investigations were carried out in a greenhouse during 240 days after the tillering stage. Spatial and temporal distributions of water content and potassium concentrations were collected using Time Domain Reflectometry (TDR) to calibrate and validate HYDRUS-2D. Simulations were carried out using hydraulic properties fitted directly to measured retention date, as well as estimated using pedotransfer functions (Rosetta Lite and the class pedotransfer of Carsel and Parrish). RMSE and MAE indicated a favorable capacity of the model to simulate soil water content using with measured properties and a better performance than estimated properties by pedotransfer functions. For the potassium concentrations, a less than optimal performance was obtained with HYDRUS-2D using both the measured hydraulic properties and the pedotransfer functions. A better understanding and accurate determination of solute concentrations in soil, uptake parameters, the crop root growth and distribution should be necessary for improve the simulations and observed data. The inability of HYDRUS-2D to accurately estimate potassium concentrations was not necessarily a limitation of model, but rather a limitation of knowledge about the soil and plant parameters involved.

The soil hydrological process plays an important role in transporting and distributing water in soils. However, the correlation between water flow behaviors, soil physical properties, infiltration patterns of soil exhibiting different soil layers, and the variation patterns in water flow behavior in rubber-based agroforestry systems remain poorly understood. Here, we mainly used dye-tracer infiltration to classify water flow behavior and HYDRUS-3D to interpret variation patterns of water flow behaviors in a rubber-based agroforestry system in southwest China. The results showed that (1) the soil of forestry patches under Hevea brasiliensis (HB) and Citrus reticulata (CR) exhibited better soil physical properties than those with no vegetation (NV). Compared with these in the NV, the saturated soil water content and field capacity increased by 15% and 21% in CR, and by 2% and 12% in HB, respectively; while the saturated hydraulic conductivity enhanced by 584% (p HB > NV. Finally, (3) the infiltration flow in soil under HB and CR exhibited a faster downward wetting front and an obvious lateral flow. These infiltration patterns compensated for the insufficiency of soil water in NV and finally caused water redistribution to be more homogenized across the whole soil profile. Therefore, our findings indicated that the rubber-based agroforestry system is a successful approach for conserving water and reducing runoff in tropical regions.

The natural environment of corn crops is being affected by climate changes. This research is aimed at evaluating the climate change scenarios resulting from the downscaling using the Eta regional climate model, nested in the global model CanESM2, and assessing the consequences of climate changes in the runoff and root water uptake of corn crops in the region of Parana, Brazil. This research also describes the climatology and the possible changes in the climate of the area, according to the different emission scenarios and infer how these changes will affect the dynamics of water in the corn crop in the region, simulated by Hydrus model. Simulations comprise of the historical period (1981–2005) and the future projections under RCP4.5 and RCP8.5, between the years 2046 to 2070. Eta model nested with the global model CanESM2 presented high ability to reproduce the climate in the region. Simulations showed changes in precipitation and an increasing trend of maximum and minimum temperatures when compared with the baseline. The root water uptake showed increasing trends predominantly in the RCP8.5 scenario. These climate changes can strongly affect corn production in the region of Parana, Brazil, as it can lead to increasing runoff and runoff extremes (runoff above 100 mm/day). This situation poses a risk to crop production since it causes losses by leaching and destruction of plants, as well as other factors such as lack of aeration and increased incidence of plant diseases. Similarly, the projected increase in temperature can result in increased evapotranspiration, which affects root water uptake, and the crop water demand.

In the subsurface irrigation management of extensively cropped vegetables, uniform crop growth requires the maintenance of uniform soil water suction at the root zone across a field. Moreover, a fixed value of suction that is suitable for crop growth should be maintained. However, accounting for the temporal and spatial changes in the suction is beyond human capability. Using HYDRUS-2D, this study modeled a spinach field in Tsukuba, Japan, which is irrigated by subsurface irrigation pipes. The subsurface pipes were located 55 cm below the soil surface. The pipes were placed 150 cm apart. Belt-shaped water shielding sheets were installed beneath the pipes. Irrigation was empirically managed. The measured physical soil properties of the spinach field were input into the model as initial values and then calibrated using the irrigation data and observed soil water suction across the field. The calibrated model was further verified by comparing the simulated and other observed suctions. After model verification, several scenarios were created by varying the given conditions: (1) the intervals of subsurface irrigation pipes, (2) the depths at which the irrigation pipes were located, (3) the existence of a water shielding sheet beneath the irrigation pipes, and (4) the shape of the water shielding sheet. These scenarios were compared, and the optimal scenario, which facilitates equal soil water suction that is close to the suction required for the growth of spinach, was selected.

Author(s): Kacimov, AR; Obnosov, YV; Simůnek, J | Abstract: Ovsinsky (1899, https://www.rulit.me/books/novaya-sistema-zemledeliya-read-193251-1.html) suggested and tested a water conserving soil no-till technology for rain-snow-fed field crops in a semiarid environment in southern Russia. We model Ovsynsky's unsaturated flow fragment, in which 1-D steady evaporation and evapotranspiration through a two-layered soil from a horizontal static water table to a dry soil surface takes place. Gardner's exponential and algebraic functions are used for the unsaturated hydraulic conductivity-suction head relations. The vertical evaporation flux depends on the dyads and triads (correspondingly) of the parameters of these functions, for example, the saturated hydraulic conductivity and the sorptive number of the two layers. The flux, as a function of the relative thickness of the upper stratum, is analytically found from the solution of one or two nonlinear equations. This relation can be nonmonotonic and exhibits either a minimum or maximum depending on whether this stratum is coarser or finer than the subjacent stratum fed from a horizontal isobar. HYDRUS-1D simulations confirm these extrema. This explains the experimental results from the literature on mulching/tillage/soil crusting-sealing, which can increase, decrease, or have no impact on evaporation from a shallow water table. Alterations of the soil's homogeneity to reduce evaporation losses can improve the hydrological balance of soil profiles.

Farmers along the main reach of the Zarqa River Basin (ZRB) commonly utilize treated wastewater for irrigation. Deep percolation is expected to occur as a result of irrigation, and it is expected that preferential flow pathways may facilitate the downward movement of irrigation water. Therefore, the aim of this research was to investigate the susceptibility of soils near Zarqa River to preferential flow, and the HYDRUS and Soil and Water Assessment Tool (SWAT) models were used. The methodology consisted of taking tension infiltrometer measurements along the Zarqa River to determine the main physical properties relevant to preferential flow, such as infiltration rate and macroscopic capillary length, followed by investigating the downward water movement using HYDRUS and SWAT. The HYDRUS simulations were conducted using single porosity (SP) and dual porosity (DP) constitutive functions pertaining to matrix and preferential flow, respectively. The in situ tension infiltrometer measurements were used to parameterize the surface layer of the HYDRUS DP model. HYDRUS simulations showed that preferential flow occurring in the surface layer of the soil profile controlled the vertical movement of soil water in excess of field capacity. The comparison between SWAT, SP and DP showed that both SWAT and DP were capable of simulating preferential flow in arid watersheds. However, SWAT simulations of lateral discharge and deep percolation resemble that of the DP only when the evaporation soil compensation factor (ESCO) was set to a value of 0.8 and the length of the soil slope was set to its maximum value. This research recommends using HYDRUS model to verify SWAT model predictions of soil water redistribution in the soil profile and to improve the parameterization of the SWAT model. The research also suggests an approach for the combined use of both models.

The HYDRUS-2D simulation software has been used for irrigation management. Its performance under realistic irrigation regimes requires evaluation with new methodologies that integrate larger soil volumes, because soil water content is highly variable in time, space and scale. We compare direct measurements in a sloping field environment under drip irrigation with simulation using HYDRUS-2D. An advanced mobile sensor technology is used to track the dynamics of soil water content, and thus of unsaturated flow, at 0.25 m and 0.50 m depth in a field plot (6 m × 3 m; 4° slope) beneath two parallel (0.5 m separation; 7 emitters per delivery tube) dripper arrays. We document an asynchronous sequence of wetting fronts driven by the sloping surface and capture the field results well using HYDRUS-2D, in the spatial (R2 = 0.935–0.963, p

Though forming a fundamental component of the water budget, soil evaporation is challenging to quantify in practice. Most water balance and soil moisture studies rely on pan evaporation or empirical relations to calculate evaporation, which is later used for water budget estimation. This study is based on the in situ measurement of soil evaporation in arid regions using smart field lysimeters. These lysimeters calculate the actual evaporation and downward leakage within the soil column using changes in weight, in addition to measuring temperature, soil moisture, soil matric potential, and other ancillary parameters in real time. The study analyses 17 months of data collected from two smart-field lysimeters installed in loamy soil within unirrigated land in Qatar. Lysimeter data were validated using a 1D numerical unsaturated flow model using Hydrus, and utilized laboratory testing results of the water retention. The Hydrus model output shows a good match between numerical and lysimeter results. The volumetric soil moisture of the topsoil in the lysimeters varies between 6% and 36%, with a rapid response to rainfall events. The actual recharge based on data analysis amounts to 5% of the annual rainfall. An analysis of the results reveals a substantial difference between the potential evaporation and the actual evaporation. While the potential values can be adequate for wet countries where rainfall is high, it is irrelevant in arid countries, due to the lack of moisture available for evaporation throughout most of the year. Results also show that while the topsoil responds quickly to rainfall events, it takes a considerable amount of time until such effects are propagated to below the soil’s lower boundary. The findings of this study may help decision makers, researchers, and irrigation engineers plan for the sustainable management and protection of scarce resources.