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Contrary to the continuum hypothesis, which averages water flow across the entire domain, including both grains and pores, the line-element model concentrates unsaturated flow in the pore space in the intermediate region of horizontal and vertical channels. The flux equivalent principle is used to deduce the equivalent unsaturated hydraulic conductivity, the flow velocity and the continuity equations. It is found that the relative hydraulic conductivities derived from the line-element model and the continuum model are identical. The continuity equations in the two models are also similar, except that the coefficient in the water content term is half that in the line-element model. Thus, the unsaturated flow problem in porous media is transformed into a one-dimensional problem. A dimension-reduced finite line-element method is proposed that includes a complementary algorithm for Signorini's-type boundary conditions involving the seepage-face boundary and the infiltration boundary. The validity of the proposed model is then proved by good agreement with analytical, experimental and simulated results for one-dimensional infiltration in a vertical soil column, unsaturated flow in a sand flume with drainage tunnels, and transient unsaturated flow water-table recharge in a soil slab, respectively. In general, the proposed method has good computational efficiency, especially for smaller mesh sizes and short time intervals. [ABSTRACT FROM AUTHOR]

The effect of permeable pavement in reducing stormwater runoff is dependent on its infiltration performance. The monitoring and modeling methods were adopted to analyze infiltration performance of permeable pavement and was primarily based on Darcy's law in previous studies. But Darcy's law disregards the changing infiltration rate with the change of water content in permeable pavement medias. Neglecting the infiltration rate change frequently resulted in significant deviation between the monitoring and modeling results. To address these issues, the accuracy of two modeling methods for the infiltration performance of permeable brick pavement system (PBPs) was evaluated. The first is the low impact development (LID) module of the stormwater management model (SWMM), and the second is a new equivalent modeling approach based on the Horton model for PBPs. According to the results, the Horton model accurately described the infiltration performance of PBPs in SWMM. Under high return periods situation, the coefficients of determination (R2) and Nash-Sutcliffe efficiency coefficients (Ens) reach 0.82 and 0.88, respectively, and the simulation error ranges from 6.57% to 8.75%. The experimental and simulation results of the LID module in SWMM were compared in greater detail. The result demonstrated that the LID module of SWMM underestimated the infiltration capacity of PBPs because it ignored the fluctuating infiltration rate throughout the whole PBPs infiltration process. Therefore, the proposed equivalent modeling method is superior to simulating the infiltration performance of PBPs in SWMM , and the Horton model improved the simulation accuracy of PBPs infiltration. [ABSTRACT FROM AUTHOR]

A rapid change in the pore water pressure of unsaturated soil due to a wetting front is a crucial factor and may result in instabilities in layered slopes. This study presents preliminary research on such a change, which we define as the seepage hammer effect. Vertical infiltration with multiple soil layers by column test was implemented to investigate the mechanism of the seepage hammer effect and distinguish it from the well-known Lisse effect and reverse Wieringermeer effect. A two-phase flow model was utilized to understand the evolutions of pore water/air pressure and volumetric water content, and its result evolved into a layered infinite slope stability analysis. Thus, the impacts of the seepage hammer effect on slope stability can be analyzed. This study found that the seepage hammer effect was triggered when the wetting front reached the interface of multiple layers and impermeable layers, and the rising speed of pore water pressure was proportional to the air venting capacity of soil. Slope stability analysis showed that the safety factor may decline suddenly because of the seepage hammer effect. Its relationship with the factor of safety and the sliding velocity is proportional. The detection of the seepage hammer effect could be a potential application of the study of fast-moving landslides. [ABSTRACT FROM AUTHOR]

The present study discusses the effect of hydraulic loading in terms of water infiltration caused by rainfall on load-mobilization mechanism of single-pile (SP) and monopile–raft foundation (MPRF) embedded in unsaturated sand by means of the finite element-based computer program Plaxis3D. Soil was modeled using the conventional Mohr–Coulomb model incorporating Bishop's effective stress, and the hydromechanical behavior was incorporated using the van Genuchten model. A fully coupled flow deformation analysis based on Biot's theory of consolidation was employed to model the behavior of soil during water infiltration. Water infiltration at different rates ranging from 5 to 864 mm/day was simulated using the time-dependent flow boundary condition at the ground surface. After successful validation of the developed numerical model using the experimental study available in literature, the evolution of suction, effective saturation, and suction stress during the different rates of infiltration was investigated and the responses of SP and MPRF in terms of settlement and axial forces were obtained. The results indicated the contribution of suction stress in increasing the stiffness of soil to an infiltration rate of 240 mm/day, thereby increasing the capacities of both SP and MPRF. The mobilization of shaft resistance was greatly dependent on the suction stress, and a reduction in the suction stress upon infiltration led to a lesser mobilization of shaft resistances (reduced around 6%). This caused a higher pile deformation, leading to further mobilization of pile base resistance. The rate of infiltration and the raft dimension has significant effect on mobilization of raft and pile resistance within MPRF due to raft–soil and pile–raft interactions. A higher rate of infiltration led to a greater mobilization of pile resistance due to positive pile–raft interaction brought by reduction in the contribution of raft base resistance that was associated with reduction in Bishop's stress. The outcome of the present study would help in better understanding the effect of hydraulic loading on the behavior of SP and MPRF and can be extended to pile group and combined pile–raft foundation. [ABSTRACT FROM AUTHOR]

In the present study, the three-parameter one-dimensional vertical infiltration equation recently proposed by Poulovassilis and Argyrokastritis is examined. The equation includes the saturated hydraulic conductivity (Ks), soil sorptivity (S), and an additional parameter c; it is valid for all infiltration times. The c parameter is a fitting parameter that depends on the type of porous medium. The equation is characterized by the incorporation of the exact contribution of the pressure head gradient to flow during the vertical infiltration process. The application of the equation in eight porous media showed that it approaches to the known two-parameter Green–Ampt infiltration equation for parameter c = 0.300, while it approaches to the two-parameter infiltration equation of Talsma–Parlange for c = 0.750, which are the two extreme limits of the cumulative infiltration of soils. The c parameter value of 0.500 can be representative of the infiltration behavior of many soils for non-ponded conditions, and consequently, the equation can be converted into a two-parameter one. The determination of Ks, S, and c using one-dimensional vertical infiltration data from eight soils was also investigated with the help of the Excel Solver application. The results showed that when all three parameters are considered as adjustment parameters, accurate predictions of S and Ks are not achieved, while if the parameter c is fixed at 0.500, the prediction of S and Ks is very satisfactory. Specifically, in the first case, the maximum relative error values were 33.29% and 39.53% for S and Ks, respectively, while for the second case, the corresponding values were 13.25% and 17.42%. [ABSTRACT FROM AUTHOR]

A distinctive slope stabilisation method that integrates two well-developed methods for slope stabilisation is analysed in this paper. The slope stabilisation method utilises embedded piles and geogrid-reinforced retaining walls with gabion basket wall facing. To study the effect of this integrated slope stabilisation method on the stability of the slope under the negative impacts of rainfall, a three-dimensional finite element model with fluid–solid coupling is adopted to indicate the rainfall infiltration process and investigate the corresponding slope responses. The shear strength reduction method is applied after fluid–solid coupling analysis to investigate the impact of various rainfall intensities and rainfall patterns on the stability of slopes with different configurations. The results from the comparison of slope responses among various configurations indicate that under the highest rainfall intensity, the integrated method improves the stability of the slope up to 41.2 % and restrains the displacement increment of the road edge to a maximum of 12.5 mm. The most critical rainfall pattern for the stability of the slope has also been recognised in terms of the factor of safety and the variation in the negative pore-water pressure of the slope. The numerical results indicate that the back-loaded rainfall pattern always yields the lowest factor of safety and induces the highest loss of matric suction, which can be 23 kPa at the toe of the slope. Moreover, a comparison between two construction scenarios under various rainfall intensities was also conducted, which demonstrates that the reinforced filled slope configuration is preferable when the site conditions permit. [ABSTRACT FROM AUTHOR]

Multiphase flow in porous media is involved in various natural and industrial applications, including water infiltration into soils, carbon geosequestration, and underground hydrogen storage. Understanding the invasion morphology at the pore scale is critical for better prediction of flow properties at the continuum scale in partially saturated permeable media. The deep learning method, as a promising technique to estimate the flow transport processes in porous media, has gained significant attention. However, existing works have mainly focused on single-phase flow, whereas the capability of data-driven techniques has yet to be applied to the pore-scale modeling of fluid–fluid displacement in porous media. Here, the conditional generative adversarial network is applied for pore-scale modeling of multiphase flow in two-dimensional porous media. The network is trained based on a data set of porous media generated using a particle-deposition method, with the corresponding invasion morphologies after the displacement processes calculated using a recently developed interface tracking algorithm. The results demonstrate the capability of data-driven techniques in predicting both fluid saturation and spatial distribution. It is also shown that the method can be generalized to estimate fluid distribution under different wetting conditions and particle shapes. This work represents the first effort at the application of the deep learning method for pore-scale modeling of immiscible fluid displacement and highlights the strength of data-driven techniques for surrogate modeling of multiphase flow in porous media. [ABSTRACT FROM AUTHOR]

The uneven pore water distribution in unsaturated soil will cause water movement, change the hydraulic and mechanical characteristics of soil, and then cause soil damage. Therefore, it is important to study the hydraulic characteristics of unsaturated soil. In this paper, the law of conservation of mass and Darcy's law were used to analyze the unit soil after seepage to obtain a continuous equation. Combined with the soil-water characteristic curve (SWCC), the effect of matric suction and permeability coefficient of unsaturated soil on infiltration rate is substituted into the equation. Through the analysis of pore water stress of the unit soil, the function of the unsaturated permeability coefficient with the effective saturation degree is obtained, and the theoretical formula of the one-dimensional infiltration rate of unsaturated soil is derived. Compared with other models, this formula has fewer parameters and is easy to use. [ABSTRACT FROM AUTHOR]

Rainfall infiltration is the primary factor that induces landslides. In this paper, discrete element software (PFC3D) was used to establish a novel rainfall infiltration model, which integrates water transfer, intensity decay and seepage force into the calculation of the moisture field. By applying this model to the rainfall infiltration analysis of a road slope in Nanping City, Fujian Province, China, the distribution law of water content, the functional relationship between shear strength and water content, and the calculation of permeability at different times can be obtained. The model was verified by comparing simulated results of water content with field monitoring data. The simulation error of water content is lower than 10%. Furthermore, this model application was validated by reproducing the pressure variation of the retaining wall on 12 May 2022. To obtain the accuracy of this model application, it was compared with saturated water content model and seepage force model. The comparison results of the three models showed that the simulation results of this model are best matching with the observation data. Moreover, the verification and validation indicate that our proposed model can be used to effectively analyze the rainfall infiltration of road slope. [ABSTRACT FROM AUTHOR]

Soil preferential flow is an essential process that affects the movement and relocation of soil water and solutes. This study was conducted on cropland in an arid and semi-arid area in Zhongning County, Ningxia. According to the different cracks, rain intensity, rainfall duration, and slope, there were three groups, and 17 dye tracer experiments were conducted in the field. We quantified the characteristics of soil preferential flow by investigating and analyzing the infiltration depth, dyeing area, saturation, runoff coefficient, and rainfall infiltration coefficient using the dye tracer method. The results showed that increasing the rainfall or irrigation intensity could promote the activation of the fracture channel as the preferential flow channel, which is advantageous to the preferential flow formation. The fractures dominated the formation of the preferential flow. The fractures slowed the formation of runoff, reduced the velocity of slope flow, reduced the flow of the slope, and increased the amount of soil water infiltration. These results have theoretical and practical significance for understanding soil water transportation, especially for agricultural irrigation management and improving cropland water use efficiency in arid and semi-arid areas. [ABSTRACT FROM AUTHOR]

The fly-ash dam is used to store the fly ash discharged from the thermal power plant. A fly-ash dam is a special slope built with fly ash, and rainfall infiltration is an important reason to induce the landslide of this kind of slope. In this paper, the laboratory tests of different slope ratios and initial seepage fields under rainfall were carried out, aimed at studying the failure mechanism, failure mode, triggering mechanism, and influence factors for the slope instability of the fly ash dam slope under rainfall infiltration. The results show that: (I) Three failure mechanisms were found in the tests: sliding failure, runoff erosion, and flow-slide failure. Due to the low density of fly ash, runoff erosion is more likely to occur under rainfall. Differently from clay slope, flow slide is an important failure mechanism of fly ash slope under rainfall. (II) Local erosion damages caused by runoff erosion and flow slide are the important triggering factors of the fly-ash dam slope failure under rainfall. (III) Three failure modes were observed in the test: the overall sliding failure of the slope, the retrogressive landslide caused by multi-stage local sliding, and the gradual erosion failure of the slope (caused by the combined action of runoff erosion and flow slide). (IV) The slope ratio has an important influence on the failure mode. With the decrease in slope ratio, the failure mode evolves from sliding failure to flow-slide failure and runoff erosion failure. The greater the slope ratio, the more obvious the sliding failure characteristics; the lower the slope rate, the greater the runoff erosion damage. The existence of an internal seepage field in the slope intensifies the occurrence of flow slide. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Earth and rockfill dams • Evolution of the seepage field • Three-dimensional electric field change law. Seepage is a common disease of earth and rock embankment dams, but due to the complex geological conditions, its location and seepage diameter are more difficult to be accurately detected. In order to accurately determine the seepage damage state of earth and rock dam materials during the evolution of seepage field, and to clarify the change rule of three-dimensional electric field of earth and rock embankment dams during the evolution of seepage field, this paper establishes a correlation model between seepage field and electric field based on porosity. Based on the model, the relationship between resistivity and critical hydraulic ratio drop during the infiltration damage of soil and rock dam is determined, focusing on the study of the three-dimensional electric field in the infiltration process of soil and rock dam body with the seepage field change characteristics and change rules, and obtaining the electric field response characteristics of the seepage field of the different hidden bodies, which provides a diagnostic basis for the realization of the subsequent leakage diagnostic technology of soil and rock dam s. [ABSTRACT FROM AUTHOR]

The seepage evolution characteristics and stability change rule of granite residual soil inside the high cutting slope under the action of rainfall infiltration were studied. Based on the saturated-unsaturated seepage theory, the numerical simulation of the rainwater infiltration path inside the granite residual soil slope was carried out under the condition of rainwater infiltration. The evolution characteristics of the seepage field of the granite residual soil cutting high slope under the condition of rainfall infiltration were revealed, and the influence of the rainwater infiltration on the stability of the granite residual soil slope was mainly studied. The research results show that with the accumulation of rainfall infiltration, the pore water pressure of the granite residual soil slope increases continuously, and the pore water pressure of the soil below the platform increases the fastest. With the increase in elevation, the water content of the slope presents a wave crest distribution. In the early stage of rainfall, the seepage velocity vector distribution on the slope surface is relatively uniform. In the middle stage of rainfall, the seepage velocity vector is the most dense at the platform, and the rainwater migration rate is accelerated. In the later stage of rainfall, the infiltrated rainwater at the slope angle of the first-level slope spreads to the surrounding area. With the continuous rainfall, the slope stability safety factor gradually decreased unevenly, and after the rainfall stopped, it gradually increased with the rainwater infiltration. [ABSTRACT FROM AUTHOR]

In this research, a full hydrodynamic model based on the numerical solution of Saint–Venant equations is described to simulate the advance phase of surface irrigation. The full hydrodynamic model is the complete form of Saint–Venant equations. This model is the most complex and accurate among all models and can be applied for analyzing the flow hydraulics and managing surface irrigation. The Preissmann finite difference scheme was used for implicit discretizing terms of the equations. The model presented herein is able to give cumulative infiltration and hydraulic properties including discharge, velocity and depth of flow for any time and distance which can be introduced as an upper boundary condition in water transport models in soil. The model was used to evaluate different situations and soil textures, and the results were compared with results of SIRMOD software, which indicated that relative error was less than 4%. The accuracy of the model was also evaluated in comparison with observed data, and the result showed that the model is able to estimate advance time with normalized root-mean-square error (NRMSE) of less than 8%. Conventional relationships of surface and subsurface shape factor overestimate them by as much as 4.7 and 17.2%, respectively, based on the inflow rate. [ABSTRACT FROM AUTHOR]

A sloping farmland has been widely considered a major contributor to the sediment yield in Southwestern China. Numerous measures have also been launched to control soil erosion and land degradation in recent years. Among them, the soil bund has been widely adopted for the water flow regulation of soil conservation or land reconstruction in the sloping farmlands. However, the stability of the bund depends mainly on the crack seepage under the soil conservation. The objective of the present study is to reveal the features of water seepage in the soil bunds under different degrees of crack development on the purple-soil sloping farmlands. Photography and laboratory digital image processing were also carried out to determine the degrees of crack development for the bunds in the Beibei District, Chongqing of China. Three typical purple soil bunds were selected as the cases for infiltration experiments, including the heavy, medium, and slight crack developments. The double-ring and four infiltration models were applied to simulate the infiltration process, such as the Kostiakov, Mezencev, Horton, and Phillip model. The results showed that: 1) The Crack Area Ratio (CAR) was applied to establish the four types of crack development degrees, including the slight (CAR≤3.5%), medium (3.5%10%). 2) The infiltration processes of all soil bunds dropped steeply, then decreased slowly till stable. The infiltration rate of crack development bunds was also much higher than that without cracks, where the difference also decreased with time. Correspondingly, the soil permeability was significantly improved with the enhancement of crack development degrees. However, there was an outstanding difference in the increment of initial infiltration rate, the mean infiltration rate, the stable infiltration rate, and 120 min cumulative infiltration, among the testing crack development degrees from no crack development to heavy development crack. The maximum increment occurred in the initial infiltration rate (98.72%), 1.01, 1.12, and 1.02 times than that of the mean infiltration rate, stable infiltration rate, and 120 min cumulative infiltration, respectively. 3) The capability of soil infiltration under different degrees of crack development was still highly correlated with the intensity of crack development after removing the influence of initial moisture content. The maximum depth of crack and the ratio of Area And Perimeter (RAP) were significantly positively correlated with the initial infiltration rate, the mean infiltration rate, and 120 min cumulative infiltration (P<0.05), whereas, the CAR was only significantly positively correlated with the mean infiltration rate (P<0.05). 4) The Kostiakov model and Mezencev model presented the better fitting to simulate and predict the bund infiltration under the different degrees of crack development (with a mean R2 of 0.95 and 0.94, respectively), followed by the Horton model (the mean R2 of 0.83). The Phillip model was the lowest in fitting on the soil infiltration with the mean R2 of 0.74. The Kostiakov model can be only applied to effectively represent the infiltration state of the bund with the development of the cracks when the infiltration time period is specified. But it gives rise to an infiltration rate value of zero when the infiltration time becomes infinite, no infiltration could reach a real state in the field. The findings can provide a strong reference for the instability mechanism of crack development in the bunds construction, maintenance, and rational utilization on the purple soil sloping farmlands. [ABSTRACT FROM AUTHOR]

• The fitting accuracy of selected models was investigated under different experiment conditions. • An optimal infiltration model was proposed for bioretention. • Evaluating the optimal model with simulated runoff process for its flexibility and reliability. Bioretention is one of low-impact development measures, which widely used not only because it can reduce stormwater runoff total volume, decrease peak flow rate and delay peak flow time, but also can remove the runoff pollutants. Infiltration is an important hydrological process for bioretention to evaluate its runoff total volume reduction and pollutants removal. So, it is important to find an optimal infiltration model that can well describe the infiltration performance of bioretention. The Horton, Philip and Kostiakov infiltration models were selected to compare their accuracy when using for describe the infiltration characteristics of bioretention, and the errors between the different models simulate results and experiment results were assessed via the maximum absolute error (MAE), bias and coefficient of determination (R2). The experimental results showed that Horton model is fitting well and flexible under different experiment conditions, especially when the hydraulic head was 10 cm, with MAE of 0.50–0.81 cm/h, bias of 0.1–0.23 cm/h and R2 of 0.98–0.99. R2 of the Philip and Kostiakov models were all over than 0.87 at the initial infiltration period, but the model fitting accuracy decreased significantly with infiltration time elapse. Furthermore, the total runoff volume capture ratio and emptying time were advanced used to evaluate the flexibility of Horton model, and the Nash-Sutcliffe efficiency coefficients of them were over than 0.61 and 0.58, respectively. Therefore, the Horton model can be optimal selected to describe the infiltration process of bioretention and for its hydrological evaluation. [ABSTRACT FROM AUTHOR]

Rainfall infiltration experiments were conducted on an unsaturated slope consisting of two-layer soils. The water content and the pore-water pressure in the slope were monitored. The monitored data are analysed and discussed in the paper. The analysis indicates that the water content and the pore-water pressure in the model slope change with the depth and that their change conditions are related with the physical properties of soils. These characteristics are different from single-layer slope significantly. The response time of the water content and the pore-water pressure increases with the slope depth. The water content and the pore-water pressure of the lower layer decrease faster than those of the upper layer. Under the same rainfall intensity, the water content and the pore-water pressure develop with the duration of rainfall until the steady seepage. The response time is quicker when the rainfall intensity is higher. However, the time effect is not significant near the slope surface. The pore-water pressure and water content in the upper layer of the model slope show more marked changes than those in the lower layer. Antecedent rainfall greatly affects the pore-water pressure and water content profiles before the steady seepage state, especially at early stage of rainfall infiltration in unsaturated regions. [ABSTRACT FROM AUTHOR]

Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model. The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments. However, whether a slope can actually seal pore air continues to be debated by researchers. In this study, a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope, and a field experiment is conducted to realistically test the sealing conditions of a slope. According to the numerical simulation, the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the "inhalation zone" and "overflow zone", respectively. Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level, and it causes pore air pressure to reach the cm level. A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration. Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process. The monitoring results show that the pore air pressure in the slope changed, which indicates that the slope can seal air. Moreover, the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall, which agrees well with the numerical simulation results. [ABSTRACT FROM AUTHOR]

Surface water impoundment in an unlined triangular ditch during a single managed aquifer recharge (MAR) infiltration pulse lasts for time Te , after which all initially disposed water seeps into a homogenous isotropic coarse soil. In ditches with initial water W0 with depth H0 and length L , the dyad (W0,H0) vanishes at t→Te. The ditch slope that minimizes an objective function involving a linear combination of Te , W0 , and H0 with arbitrary cost coefficients was found. The analytical expression for Te as a function of the bank slope and the sand's porosity is for soils without capillarity and mild bank slopes. An isoperimetric constraint in optimization is the volume of the water pulse released into the ditch. A global unique minimum exists if the coefficients factoring W0 and H0 are not identically zero. A numerical solution to a two-dimensional infiltration problem was obtained using HYDRUS 2D/3D and its reservoir boundary condition option for arbitrary soils and bank slopes. Optimal slopes of triangular ditches were found for an initially dry loam. The analytical and numerical optimal shapes were not sensitive to mild variations of the ditch slope. [ABSTRACT FROM AUTHOR]

Microtopography (MT) can govern runoff dynamics as a net result of local heterogeneities in the flow paths and ponding. This in turn controls the development of the surface water layer that connects and flows downslope. It is therefore important to understand which microtopographic features affect runoff generation dynamics and its macroscopic—hillslope scale—hydrological signatures (e.g., hydrographs, runoff and infiltration volumes). In this study, we numerically solve 2D overland flow from a single rain pulse on 1,460 idealized hillslopes with different slopes and sinusoidal microtopographies and different infiltration capacities. We assess hydrodynamic distributions, hydrographs and hydrological indices to assess the effects of MT and infiltration on the (local) hydrodynamic and (larger scale) hydrologic responses in terms of surface runoff regimes. The results show that MT enhances infiltration and that infiltration and runoff depend in a strong non‐linear way on slope and the properties of MT. Three regimes of influence of MT were identified: one in which MT plays a negligible role but there is a high sensitivity to the infiltration capacity curve, a second regime in which hydrological partitioning is highly sensitive to MT and the infiltration capacity curve, and a third regime in which MT increases infiltration, but the response is insensitive to particular features, and more affected by the average slopes. The regimes are the product of the interplay between small (MT) and large scale (slope) properties. Furthermore, the results suggest that hydrological signatures can be interpreted and explained by the spatiotemporal variation of surface connectivity. Key Points: Microtopography plays a relevant role in rainfall‐runoff‐infiltration partitioningDifferent slopes and microtopographies result in a set of hydrodynamic regimesThe hydrodynamic regimes can be related to hydrological regimes [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional (2D) numerical model of soil erosion and sediment transport resulting from rainfall induced overland flow. It is a spatial and temporal dynamic model combining physical and empirical laws and comprises: i) An overland flow module that solves the two-dimensional unsteady water flow equations on an infiltrating surface; ii) A soil infiltration module that uses a combined Horton-SCS scheme; and iii) A soil erosion and sediment transport module that solves the two-dimensional sediment transport equation, distinguishing between rill erosion, interrill erosion and sediment deposition. The performance of the model was evaluated by comparing its results with observed data from laboratory rainfall-runoff experiments on a two-directional 2.00 × 2.00 m2 soil flume set at 1% and 10% slopes in the x- and y-directions, respectively. The x-direction produced remarkably lower runoff and transported sediments than the y-direction. The numerical model significantly underestimated x-direction lower values of runoff and transported sediments. However, in the y-direction the model presented very good performance. Overall, in total terms (x- plus y-direction), the numerically simulated graphs of runoff and sediment transport were in very good agreement with corresponding experimental measurements, demonstrating the laboratory proof-of-concept of the model. [ABSTRACT FROM AUTHOR]

Objectives: Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico. Data description: The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400–2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communities adjust to a changing climate/environment. [ABSTRACT FROM AUTHOR]

Purpose: The remediation of diesel-contaminated hydrophobic soil is difficult due to the inability of aqueous phase remedial agents to infiltrate the soil. This novel laboratory study enhanced the gravity-driven infiltration of water and oxidant solution into the hydrophobic soil by pretreatment. For this purpose, the hydrophobic soil was pretreated (partially liquid saturating) using 0.1% sodium hexa-metaphosphate (Na-HMP) and 0.5% alpha olefin sulfonate (AOS). Methods: The diesel-contaminated soil (34,167 ± 560 mg TPH/kg) was partially saturated with 0.5 pore volumes of Na-HMP and surfactant mixture solution. The infiltration experiment of the pretreated soil was conducted by pouring a solution (water/oxidant) provided from the Marriott reservoir over the digital balance. Results and discussion: This study did not observe any natural infiltration of water or oxidant reagent into the diesel-contaminated soil. After the pretreatment, the cumulative infiltration of water to the pretreated soil increased to 5.17 cm after 40 min. The natural infiltration occurred due to the dispersion of soil particles and reduction of hydrophobicity by the Na-HMP and AOS, respectively. Widened soil pores were observed after pretreatment using the scanning electron microscopy (SEM) analysis. The infiltration of 5% Na2S2O8 solution was 5.80 cm after 40 min when the diesel-contaminated soil was pretreated with 0.1% Na-HMP and 0.5% AOS. Conclusions: Pretreatment using Na-HMP and AOS can enhance the remediation of highly hydrophobic and low-permeability soils. This finding can provide an insight into enhancing the soil remediation efficiency by increasing the gravity-driven uniform delivery of the remediation agent into the undisturbed soil. Graphical abstract [ABSTRACT FROM AUTHOR]

Conservation tillage has become a promising farming technology with mechanized operations as the main means. The method of minimum tillage or no tillage planting is widely adopted, where the crop straw and stubble are used to cover on the soil surface, in order to effectively reduce the soil wind erosion and water erosion, while improve the ability of soil to keep moisture and water. As a kind of conservation tillage, mulch tillage is mainly used to chop up the straw by a combined tillage machine and mix it evenly into the soil. As such, the mulch tillage can contribute to soil moisture infiltration, and high-quality seed beds. After the corn harvest in the first autumn, the full amount of straw-covered arable land was operated directly by the combined soil planter with the soft rake. In the second spring, the seed bed making machine was used to prepare the whole field of the seed bed, to build a high-quality seed bed and improve the emergence rate of corn. Most previous research focused on the effect of straw mulching and tillage methods on soil moisture infiltration performance. However, it is of great significance to explore the suitable straw returning and tillage method for soil protection in black soil area. In this study, a Design Expert software and a Box-Behnken test were used to conduct an experimental study on the infiltration performance of straw on soil moisture in black soil area in mulching tillage. In the column experiment, a quadratic regression orthogonal experiment was designed with three factors and three levels, including the depth, the quantity, and the length of mixed straw. The experimental results showed that the significant order of the influence on the amount of water seepage was as follows: the depth of mixed straw, the length of straw, the quantity of mixed straw. A response surface mathematical model was established to analyze the influence of various factors on soil moisture infiltration performance, and thereby to comprehensively optimize the influencing factors. The optimal combination was achieved, where the water seepage reached the maximum, when the depth of mixed straw was 20 cm, the quantity of mixed straw was 80%, and the length of straw was 9 cm. Using the optimized parameters for experiments, the soil water infiltration rate was up to 0.247 L. The findings can provide a sound reference for the adjustment parameters in the combined tillage machine in the mulch tillage, particularly on a theoretical support for black soil protection. [ABSTRACT FROM AUTHOR]

Copyright of Revista Agrotecnologia is the property of Universidade Estadual de Goias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Metal-contaminated mining soils pose serious environmental and health risks if not properly managed, especially in mountainous areas, which are more susceptible to perturbation. Currently, climate change is leading to more frequent and intense rain events, which cause flooding episodes, thereby altering soil redox equilibria and contaminants stability. We evaluated the potential release of Zn and Cd (two of the most common inorganic contaminants) and the factors regulating their solubility and speciation in two heavily contaminated soils representative of a Zn-mining area. The soils were flooded under aerobic (for 24 h) and anaerobic (for 62 days) conditions using mesocosm experiments, sequential extractions, and geochemical modelling. Leaching trials under aerobic conditions showed a high release of Zn and Cd (10 times the legislative limits), with metals possibly migrating via water infiltration or runoff. Under anaerobic conditions Zn and Cd were initially released. Then, solution concentrations decreased gradually (Zn) or sharply (Cd) until the end of the experiment. Sequential extractions and multisurface modelling indicated that both metals precipitated mainly as carbonates. This was confirmed by a geochemical multisurface modelling, which also predicted the formation of sulphides after 60 days in one soil. The model calculated metals to be preferentially complexed by organic matter and well predicted the observed soil solution concentrations. The results showed that during flooding episodes contaminants could be promptly transferred to other environmental compartments. The use of multisurface modelling coupled with laboratory experiments provided useful indications on the potential release and speciation in case of anoxic conditions. [ABSTRACT FROM AUTHOR]

Wombats are large marsupial grazers native to Australia. They are 'ecosystem engineers' due to their burrowing, impacting rates of soil turnover, assisting with nutrient cycling and water infiltration, and creating habitat for other species. The aim of this review is to provide an overview of available information on the habitat and distribution, abundance and threats to bare-nosed wombats (Vombatus ursinus), and to provide a critical review of the current gaps in our knowledge to aid future management of the species. Bare-nosed wombats were previously widespread. Since European settlement their range has reduced. While habitat loss and contraction impact population numbers, bare-nosed wombat populations are also threatened by roadkill, introduced species, legal and illegal human persecution, and disease. Further research is required to understand the historic range of bare-nosed wombats, as well as current population numbers, so that we can determine the threats that most significantly impact this species. Increasing our understanding of habitat requirements, distribution and population numbers, as well as how to mitigate threats, will aid future management and conservation strategies for the species. Bare-nosed wombats (Vombatus ursinus) are native Australian marsupials. Since European arrival, the wombat has lost habitat and population numbers through a number of threats including road kill, introduced species, disease and culling. This review provides an overview of current research on wombats, focusing on their distribution, population and threats. The gaps identified through this review include distribution, population numbers and threat mitigation. Further research in these areas is necessary to improve species conservation. Photograph by Julie Old. [ABSTRACT FROM AUTHOR]

The objective of this study was to quantify water infiltration and resistance to penetration in a Latossolo Vermelho Distrófico (Typic Haplustox) cultivated with different land use systems and in a degraded pasture area. The studied areas are located in Rio Verde, state of Goiás (Brazil), where seven treatments were evaluated: T1 - Degraded; T2 - Fertilized pasture; T3 - Conventional; T4 - Crop-forest integration system (CFI); T5 - Livestock-forest integration system (LFI); T6 - crop-livestock-forest integration system (CLFI - hay); and T7 - crop-livestock-forest integration system (CLFI - silage). The water infiltration speed curves and the respective basic infiltration rate (BIR) values for the areas under study were determined. The infiltration of water into the soil was determined “in situ” by the double ring infiltrometer method and empirically through models proposed by Kostiakov and Kostiakov-Lewis. The soil resistance to penetration, up to a depth of 0.3 m, was performed using an impact penetrometer. The greatest infiltration in relation to time occurred in treatment T7. The highest values of BIR occurred in treatment T5. The model proposed by Kostiakov showed greater adjustment to the infiltration speed data obtained in the field. The lower resistance of the soil to penetration is provided by the diversity of species in the T4 treatment. The different management systems for recovering degraded pastures influenced the soil quality indicators studied, but there is a need for further studies to adjust the stocking rates in integrated systems in order not to return to the degradation scenario. [ABSTRACT FROM AUTHOR]

The space–time dynamics and the effect of urban growth on territory transformation were simulated with Iber 2D to analyze flooding events in the lower basin of the Sabinal River, Mexico. We classified the main coverages and land uses of the study area. Soil roughness and water infiltration in the soil were evaluated. Both values were used as input data in a simulation model with Iber 2D to analyze and compare the levels of water height and maximum flood level area with different precipitation values in two reference years, 1986 and 2014. Residential use land cover increased considerably while tree, pasture and agricultural use covers decreased. Consequently, in 2014, precipitation of similar magnitude led to higher values of direct runoff, increasing water levels and therefore the risk of overflowing. The water levels and moments of river overflow provided feedback for flood‐risk warning systems and tools to monitor basins lacking adequate infrastructure. [ABSTRACT FROM AUTHOR]

Biochar is important for optimizing soil physical structure and improving soil water retention. The saturated water capacity test, water repellency test, and permeability coefficient test were used to study the effects of biochar additive amount (0, 2, 5, 10, 15, and 20 g/kg) and particle size (>2 mm, 2 mm–0.075 mm, and <0.075 mm) on the basic physicochemical and hydraulic properties of loess. The results showed that with the increase of biochar additive content, the relative particle density decreased linearly (R2 = 0.984); the plastic limit, liquid limit, and plasticity index increased (R2 = 0.947, 0.991, and 0.984, respectively); the maximum dry density decreased (R2 = 0.900); and the optimal water content and saturated water content increased gradually. At the same time, the soil's pH increased (R2 = 0.957), the soil water repellency decreased, and the water infiltration became easier, but the soil's permeability coefficient (saturated water conductivity) decreased. When the the biochar particles size is smaller, the soil's water repellency and permeability coefficient reduced. Studies had shown that the application of biochar makes the loess infiltrate easily, seepage slowly, and contain more water, which improve the water infiltration characteristics and water retention capacity of loess. [ABSTRACT FROM AUTHOR]

For areas that supply underground water sources, it is important to identify the conditions of circulation and infiltration of surface water as a fundamental contribution to the recharge, sustainability and protection of aquifers. A study of the potential infiltration capacity considering the geomorphological aspects in the Arroyo Grande basin, Sucre, Colombia is presented. The aquifers of the study area are at risk of water supply due to the intense extraction and contamination by urban discharges in the surface currents of the basin. Morphometric indicators were applied to study the forms and dynamics of currents; For the estimation of the potential infiltration, the curve number method (CN-SCS) was used; all analyzes were performed with GIS tools. The results described the drainage conditions of the surface, identified the areas with the highest Infiltration potential over the Morroa aquifer, and the factors that directly influence the water regulation process. [ABSTRACT FROM AUTHOR]

This study aims to analyze physical parameters such as infiltration of water into the soil through rooting, water holding capacity and its effect on the temperature and humidity of the land around the plant. The method used survey method and data analysis technique is descriptive analysis, t test, F test (ANOVA). The results showed that the infiltration rate near the sago cluster was higher than outside the cluster at different seasons, the water holding capacity does not differ significantly at different altitudes, soil moisture near the cluster of sago is higher than outside the cluster in different seasons, The soil temperature near the cluster is lower than the temperature outside the cluster. Sago baruk plants have excellent ecological functions and can be recommended to be conserved to ensure sustainable utilization. [ABSTRACT FROM AUTHOR]

The paper deals with non-destructive measurement of water infiltration into homogenous soil (Haplic Chernozem) covered by grass. The experimental site was located in Most pri Bratislave (Slovakia) in the Pannonian Basin at a height of 130 m above sea level. Radioactive tracer technique was used to determine the water content of the soil profile during water infiltration. A mixture of the radioactive iodine 131I (chemical form Na131I) and the NaI solution was used as a tracer. The tracer distribution in the soil was measured by the Geiger-Müller detector connected to the nuclear analyser. Gravity-driven fingers were detected in the soil under the grass cover as a consequence of the wetting front instability. The instability manifested itself as a non-monotonic moisture profile caused by saturation overshoot and a varying discharge from the soil profile in time. [ABSTRACT FROM AUTHOR]

Precipitation plays an important role in the water supplies that support ecological restoration by sustaining large-scale artificial plantations in arid and semiarid regions, especially black locust (Robinia pseudoacacia) plantations (RP plantations), which are widely planted due to R. pseudoacacia being an excellent pioneer species. Characterizing the response of soil moisture to rainfall events at different stages of restoration is important for assessing the sustainability of restoration in RP plantations. In this study, we quantified the response of soil moisture to rainfall events at different years of restoration (15, 20 and 30 yr) representing different restoration stages in RP plantations in a typical hilly-gully area, i.e., the Yangjuangou Catchment, of the Loess Plateau, China. Over the growing season (June to September) of 2017, smart probes were placed at nine depths (10, 20, 40, 60, 80, 100, 120, 150, and 180 cm below the soil surface) to obtain volumetric soil water information at 30-min intervals in the three RP plantations. The advance of the wetting front was depicted, and the total cumulative water infiltration was measured. Soil moisture was mainly replenished by eight heavy rainfall events (mean rainfall amount = 46.3 mm), accounting for 88.7% of the rainfall during the growing season. The mean soil moisture content profiles of RP plantations at the three restoration stages were ordered as 30-yr (14.07%) > 20-yr (10.12%) > 15-yr (8.03%), and this relationship displayed temporal stability. Soil moisture was primarily replenished by rainfall at the 0–60 cm soil depth, and soil moisture remained stable below the 100-cm soil depth. The rainfall regime influenced the advancement of the wetting front. Here, a single rainfall event of 30 mm was the rainfall threshold for infiltration into the 60-cm soil layer. The total infiltration time ranged from 310.5–322.0 h, but no significant differences were found among RP plantations at different restoration stages. Young and old RP plantations had more total infiltration (more than 228.2 mm) and deeper infiltration depths (80–100 cm) than middle-aged plantations. The RP plantation at the intermediate restoration stage exhibited minimal total infiltration (174.2 mm) and a shallow infiltration depth (60 cm) due to the soil physical structure of the plot, which may have limited rain infiltration. More stand conditions that may affect infiltration should be considered for priority afforestation areas. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sand mixing measures can change the mechanical composition and texture of soil, thereby improving the efficiency of fertilizer utilization. The surface sand mixing in irrigation area can effectively solve the problem of soils with high silt content. This study explored the water-salt transport mechanisms of heavy saline-alkali soils with different contents of sand. Laboratory soil column experiments were carried out to compare the effects of different sand ratio on infiltration characteristics and water-salt transport under continuous distilled water irrigation. The soil samples were taken from 0-40 cm abandoned heavy saline-alkali farmland in Bayannur City of Inner Mongolia, China. It was located in Hetao irrigation area. In the laboratory experiments, a total of 16 treatments were set up: CK (without sand), S1(2%), S2(4%), S3(6%)…S15(30%). The results showed that: 1) With the increase of sand ratio at the surface layer of soil, the cumulative infiltration and the rate of wetting front were increased at the same time. Compared with the treatment of CK, the steady infiltration rate of soil increased by 1.1, 1.3, 1.5, 1.8, 2.1, 2.3, 2.7, 3.1, 3.6, 4.1, 4.5, 5.1, 5.7, 6.2 and 6.8 times, respectively. It indicated that the steady infiltration rate of soil increased significantly with the increase of sand mixing ratio. When the sand mixing ratio was 18%-24%, the stable infiltration rate was 0.065-0.091 mm/min; when the sand mixing ratio was 26%-30%, the stable infiltration rate was more than 0.1 mm/min, and the water holding capacity of soil was low. 2) The mean soil moisture among treatments was significant different (P<0.05) at 7, 11 and 15 days, the rate of water infiltration could be increased by increasing the proportion of soil sand, and a large proportion of sand would reduce the water holding capacity of soil. 3) When the sand-mixing ratio were less than 24%, the total salt content of the soil at day 7 was significantly different among treatments (P<0.05). The total salinity content at day 3 was 21.95-73.38 g/kg in 30 cm soil layer, showing a decreasing trend. 4) the Kostiakov model could well fit the infiltration process of soil water in this study. The empirical coefficient in Kostiakov infiltration model showed a significant increase trend. Its change range was between 4.011 and 15.443 mm/min, which indicated that the average infiltration rate during the first period was increased when sand ratio was increased. The effects of adding sand in soils on increasing soil water infiltration was obvious. Therefore, the measures of mixing sand in the surface layer of heavy saline-alkali farmland would be an effective way to alleviate soils salinization. [ABSTRACT FROM AUTHOR]

Water infiltration into layered soils is studied, considering a two dimensional spatial domain. The focus is on the treatment of discontinuity at the intersection of non-overlapping soils. The novelty of this paper is based on a mixed MoL–TMoL, which merges desirable features of both Method of Lines (MoL) and Transversal Method of Lines (TMoL); such a numerical approach allows us the numerical treatment of the solution at the discontinuous interfaces by means of Filippov theory for dynamical systems. Numerical simulations, based on implicit and semi-implicit schemes of low accuracy, are provided for validating this approach. [ABSTRACT FROM AUTHOR]

Soil compaction has detrimental effects on the physical, mechanical and hydraulic properties of soils, and affects important soil processes and function, and crop productivity. This work was conducted to investigate soil compaction impacts in integrated arable croppinglivestock systems managed under conventional tillage (CT) and no-tillage (NT). The work examined the combined effects of cattle trampling and farm machinery traffic on: soil strength, soil deformation, and water infiltration into soil. The following treatments were applied to soil (Entic Haplustoll, 60% sand) managed under CT and NT: three traffic intensities (1, 5, 7 passes) performed with light (2WD, 53 kN) and heavy (4WD, 100.4 kN) tractors, and two stocking densities (400 and 700 kg ha-1), respectively. Controls were also used to represent the condition of the soil without any effect of livestock or field traffic. In both tillage systems, soil penetration resistance (strength) increased and water infiltration into soil decreased as traffic intensities or stocking rates applied increased. There was a significant traffic intensity × stocking rate interaction, which influenced the depth and extent of soil compaction at depth. Despite these results, stubble grazing during fallow should not be discouraged as this practice offers mixed farming systems several agronomic and financial benefits. If stubble was to be grazed, the system would need to be carefully managed: (1) avoid 'random' traffic using permanent or semipermanent traffic paths to minimise the field wheeled area, (2) vacate livestock from the field, or confine it to a sacrificial area, when the soil water content exceeds a critical level above which soil damage is likely, and (3) maintain more than 60%-70% ground cover. Tillage repair treatments can be targeted to those sacrificial or 'hot-spots' areas so that localised, as supposed to widespread, compaction problems are rectified before the next crop is established. [ABSTRACT FROM AUTHOR]

Recent studies have shown that invasive earthworms can dramatically reduce native biodiversity, both above and below the ground. However, we still lack a synthetic understanding of the underlying mechanisms behind these changes, such as whether earthworm effects on soil chemical properties drive such relationships. Here, we investigated the effects of invasive earthworms on soil chemical properties (pH, water content, and the stocks and fluxes of carbon, nitrogen, and phosphorus) by conducting a meta‐analysis. Invasive earthworms generally increased soil pH, indicating that the removal of organic layers and the upward transport of more base‐rich mineral soil caused a shift in soil pH. Moreover, earthworms significantly decreased soil water content, suggesting that the burrowing activities of earthworms may have increased water infiltration of and/or increased evapotranspiration from soil. Notably, invasive earthworms had opposing effects on organic and mineral soil for carbon and nitrogen stocks, with decreases in organic, and increases in mineral soil. Nitrogen fluxes were higher in mineral soil, whereas fluxes in organic soil were not significantly affected by the presence of invasive earthworms, indicating that earthworms mobilize and redistribute nutrients among soil layers and increase overall nitrogen loss from the soil. Invasive earthworm effects on element stocks increased with ecological group richness only in organic soil. Earthworms further decreased ammonium stocks with negligible effects on nitrate stocks in organic soil, whereas they increased nitrate stocks but not ammonium stocks in mineral soil. Notably, all of these results were consistent across forest and grassland ecosystems underlining the generality of our findings. However, we found some significant differences between studies that were conducted in the field (observational and experimental settings) and in the lab, such as that the effects on soil pH decreased from field to lab settings, calling for a careful interpretation of lab findings. Our meta‐analysis provides strong empirical evidence that earthworm invasion may lead to substantial changes in soil chemical properties and element cycling in soil. Furthermore, our results can help explain the dramatic effects of invasive earthworms on native biodiversity, for example, shifts towards the dominance of grass species over herbaceous ones, as shown by recent meta‐analyses. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ambiente e Água is the property of Revista Ambiente e Agua and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the decrease of the porosity ratio, the soil undergoes compression deformation and the strength is improved. At the beginning, the stress in the soil is all borne by the pore water. Based on the exponential seepage law in soil, considering the linear distribution of the initial effective stress along the depth and the actual variable load, a one-dimensional nonlinear consolidation control equation is established. The numerical solution is obtained by the finite difference method, if the compression index is different, the development rate of deformation is no longer the same, and the smaller the compression index is, the faster the settlement rate is. The results show that with the increase of the index in the seepage law, the consolidation rate will be faster under a smaller time factor and slower under a larger time factor. However, the consolidation rate of the consolidation curve in the whole process will be accelerated with the increase of the index; the consolidation rate of the initial effective stress linearly increasing along the depth is faster than that of the uniform distribution; the faster the loading rate of the variable load is, the faster the consolidation rate is. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity is an important indicator of water movement and pore structure in soil. Therefore, it is important to determine soil physical and hydraulic properties under different land use conditions. The present study was comducted under three different landuse; dry farming (D), irrigated land (I) and pastureland (P). Three samples were colected from each field (9 samples in total). Infiltration measurements were also tested at each sampling point in each field. The results of this study showed that although hydraulic conductivity was not significantly differentt under dry and irrigated agricultural lands, significant differences were observed between the pastureland and the tilled areas. Soil water infiltration was positively correlated with soil organic matter, aggregate stability and hydraulic conductivity, whereas infiltration was negatively correlated with bulk density. The lowest infiltration rate was found under pastureland compare to those are the highest under the irrigated lands. Therefore, increasing the organic matter content of the local soils will make significant contributions to sustainable soil management. [ABSTRACT FROM AUTHOR]

Purpose: Infiltration modeling is an important tool to describe the process of water infiltration in the soil. However, direct measurements of the parameters of infiltration models are usually time-consuming and laborious. The present study proposed an effective method to estimate parameters of the Kostiakov-Lewis model (a classical infiltration model) from soil physical properties (SPPs). Materials and methods: Parameters k, α, and f0 of the Kostiakov-Lewis infiltration models were measured in 240 double-ring field experiments in Shanxi Province, China. SPPs at the corresponding experimental points were measured at the topsoil layer (TL, 0–20 cm) and the top-subsoil layer (TSL, 0–20 and 20–40 cm). The Kennard-Stone (KS) sampling method and principal component analysis (PCA) were used for dividing training samples and extracting principal components (PCs) of SPPs, respectively. Partial least squares (PLS), back-propagation neural networks (BPNNs), and a support vector machine (SVM) were used to establish models for estimating k, α, and f0 with the SPPs of TL and TSL as the input variables (IV). Results and discussion: The differences in soil density (BD), texture, and moisture content (θv) were found in topsoil and subsoil, but loading distributions of SPPs on PCs present different degrees of correlation. Moreover, SVM produced the most accurate estimation among these three methods for using the SPP of TL and TSL as inputs. The highest accuracy for k estimations was obtained by SVM using the SPP of TL as IV; R and RMSE in the model test process were 0.78 and 0.3 cm min−1, respectively. However, using SPP of TSL as IV obtained the highest accuracy for both α and f0 estimations with the SVM method (R values were 0.71 and 0.82, respectively, and RMSE values were 0.03 and 0.018 cm min−1) in the model testing. Conclusions: The SVM method with SPPs as inputs is an effective and practical method for estimating the parameters of the Kostiakov-Lewis infiltration model. [ABSTRACT FROM AUTHOR]

Tillage and stover harvest are common management practices in maize-based cropping systems around the globe. However, frequent soil disturbance and biomass export are likely to have negative long-term impacts on soil biological activity and a range of associated soil properties, and thus, there is great concern surrounding the sustainability of these practices. To address this issue, we examined soil macrofauna communities and a suite of soil chemical and physical properties in a recently established experiment (2.5 yrs. old) in Akron, Colorado. No-tillage and residue retention practices were included in a full factorial randomized block design with the following treatments: no-till + residue retention (NT/R); no-till + residue harvest (NT/RH); conventional tillage + residue retention (CT/R); and conventional tillage + residue harvest (CT/RH). In year three of the experiment, soil health parameters were assessed including: soil macrofauna diversity and abundance, aggregate stability, potential infiltration, and chemical fertility measures. The combined practice of residue retention with no-tillage (NT/R) resulted in greater macrofauna abundance, including a five-fold increase in earthworm abundance and biomass. Greater earthworm populations were associated with an increase in aggregate stability and a trend towards greater water infiltration under NT/R. While univariate tests did not reveal significant treatment differences in arthropod taxa, multivariate analyses indicated clear treatment effects on macrofauna communities, with tillage generally separating communities more than residue management. Soil chemical parameters indicated relatively less dramatic differences between treatments, but with some notable impacts of both residue retention and tillage on soil C and N dynamics. Findings from our study, among the first to examine whole soil macrofauna communities in the semi-arid Great Plains, suggest that no-till and residue retention practices offer promise for improving soil biological activity and soil structural properties of soil, especially when these two practices are employed in combination. • We assessed impacts of no-till and residue retention on soil properties after 2.5 years. • The combination of no-till and residue retention led to a 5-fold increase in earthworm abundance. • Tillage influenced soil macrofauna community composition more than residue management. • Earthworm biomass was positively correlated with aggregate stability. • Both tillage and residue management increased soil C and N pools. [ABSTRACT FROM AUTHOR]

The paper presents a case study of a landslide event, accidentally triggered by an unexpected and extraordinary infiltration in an otherwise stable slope. The work aims at modelling the slope failure mechanism with a simplified two-dimensional framework based on the formation of a perched water table. The landslide occurred in Val Venosta/Vinschgau Valley, in Northern Italy, in April 2010 and produced catastrophic consequences. It took place on a hillside with average slope angle 36° and affected an area of about 200 m2; the slip surface was located approximately 1.0 m below the slope profile, in the uppermost layers of a predominantly coarse, well-graded soil. A series of numerical simulations were performed to back-analyse the event, using a commercial computer program. The artificial water infiltration and water content evolution were modelled with a two-dimensional finite element model (FE) of the unsaturated/saturated domain with appropriate infiltration boundary conditions. The slope stability analyses were conducted with a classic limit equilibrium method (LE) and were performed at different time instants during the infiltration process. The soil-water retention curves and conductivity functions were defined according to the van Genuchten-Mualem model. The combined FE and LE simulations showed the gradual formation of a perched water table, whose associated localized pore pressure distribution resulted in the loss of the suction stabilizing effect and thus in the reduction of the safety factor. Although supported by basic soil mechanical and hydraulic characterization, the numerical simulations allowed to perform a back-analysis which effectively captured the timing of the event and the location and depth of the slip surface along the slope. [ABSTRACT FROM AUTHOR]

• 145 flume runs were performed for studying the stability of fascines. • In all cases main driver for dramatic collapse was water infiltration inside the bank. • Water infiltration increases with the river bend curvature. • Anti-scouring twigs can drastically reduce these effects by modifying the local hydraulics. We present the results of flume experiments specifically designed to investigate the conditions required for successful bank protection using fascines, considered in the early and critical stage of their installation (no developed root system), in the alpine context. A total of 145 runs were performed with erodible banks, considering different combinations of protection design (no protection, rip-raps, twigs), bed mobility (with or without bedload), discharge (from low to exceptional floods), and bend curvature radius. None of the runs showed any direct fascine grabbing by the flow observed; all destruction was the consequence of bank scouring, erosion and collapse around the structure. In all cases, most destructive effects resulted from water recirculation inside the bank. Thus, we conclude that all measures aiming to reduce water circulations during the first stage of the fascine construction and development are recommended. This include large bend curvature radii (when possible), fining of the filling material, use of antiscouring twigs, optimisation of the programming of the works with consideration of the hydrology (shape of hydrographs) and regular survey of the structure. Our experiments show that anti-scouring twigs have a real protective effect by modifying the local hydraulics and promoting sediment deposition at the bank toe. [ABSTRACT FROM AUTHOR]

Surface runoff from agricultural fields is the largest non-point source of phosphorus (P) that pollutes surface water in humid temperate regions. Best management practices have attempted to reduce P loading and improve P retention in agricultural soils, but significant losses continue to occur, emphasizing the need for novel solutions. The objective of this study was to determine whether wood-based biochars applied to an agricultural field, 3 years earlier, could reduce P loss in surface runoff by increasing water infiltration or by improving soil stability. Field plots amended with Dynamotive, Basques and Pyrovac biochars (5 and 10 t ha−1) or without biochar were subjected to 30-min of simulated rainfall to determine runoff volume, time-until-ponding, infiltration rate, and water holding capacity, as well as the P concentration and P load in runoff. The distribution of soil macro- and micro-aggregates and their total organic C and total P content was measured. Soil water dynamics were not affected by biochar amendments, however, runoff contained significantly less ortho-P in field soil amended with Dynamotive and Basques biochar at 5 t ha−1 and significantly less particulate P when amended with biochar at 10 t ha−1. Biochar-amended soil had significantly greater microaggregate stability, organic C and total P content than the control soil without biochar. The reduction in particulate P concentration in runoff may be the result of biochar integration within the microaggregate structure, which indirectly promotes P retention in macroaggregates. • Biochar amendment reduces the P loss in surface runoff from field soil. • Soils amended with biochar had greater microaggregate stability. • Macroaggregates from biochar-amended soils contained higher total P content. • Biochar may increase P integration into the soil microaggregate structure. [ABSTRACT FROM AUTHOR]

Substantial interest exists in understanding the role of low-disturbance construction methods in mitigating industrial impacts to native grassland soils and vegetation. We assessed soil and vegetation responses to conventional high-disturbance sod-stripping and revegetation on sandy soils, and the alternative practice of low-disturbance access matting to provide a temporary work surface on sandy and loamy soils. Treatments were associated with high-voltage transmission tower construction during 2014 within the Mixedgrass Prairie. High-disturbance sites were hydroseeded in May of 2015, while low-disturbance sites recovered naturally. We assessed soil physical (bulk density, water infiltration) and chemical properties (organic matter, pH, and electrical conductivity) after construction and herbage biomass for three growing seasons. Sod-stripping led to 53% greater soil bulk density and 51% less organic matter than nondisturbed controls, while water infiltration increased by 32% in these high-sand (>80%) soils. In contrast, access matting led to minimal soil property changes regardless of the texture. While total herbage biomass was unaffected by all construction treatments, sod-stripping reduced grass biomass by 80% during the first growing season, which coincided with a 119% increase in forb mass. Root biomass (0–15 cm) also declined 77% with sod-stripping. Vegetation biomass on sites with access matting remained largely unaffected by the disturbance. Overall, low-disturbance construction methods using access matting were more effective than sod-stripping in mitigating the negative impacts of industrial development on Mixedgrass soil properties, as well as vegetation biomass, and are recommended as a best management practice during industrial disturbance. [ABSTRACT FROM AUTHOR]

Purpose: Soil infiltrability is an important topic in environmental and agricultural research and influences plant growth, soil erosion and water runoff. In this study, the influences of interactions between soil particles on soil infiltrability were investigated in different MgCl2 and NaCl solutions. Materials and methods: We selected an entisol soil in Chongqing, China. The soil samples were saturated with Na+ and Mg2+: each air-dried sample was weighed into a 5-L beaker and washed three times with NaCl and MgCl2 and then deionised water, respectively. The cationic saturated soil samples were then dried at 333 K, crushed and passed through a 1-mm sieve. For water infiltration, the Na- or Mg-saturated soil samples were added and packed to a bulk density of 1.05 g cm−3 in a rectangular acrylic glass column (20 cm × 3 cm2). The NaCl or MgCl2 solution was selected to leach the soil column with a constant water head, and the depth of the wetted front was recorded at 150 min. For the computed tomography scan, the circular columns of Na- and Mg-saturated soil were wetted by 0.01 mol L−1 NaCl and MgCl2 solutions, respectively, and then were determined by computed tomography scanner when the position of wetting front reached 3 cm. Results and discussion: Soil with relatively weak electrostatic repulsion had a net attractive force, which leads to the unbroken soil aggregate and high infiltrability. The calculated net forces at the critical concentration in MgCl2 (0.005 mol L−1) and NaCl (0.25 mol L−1) were attractive and the measured soil infiltrability reached maximum value. The calculations of particle–particle interaction forces also showed that, when the soil aggregate did not break down, the electrostatic repulsive forces caused the soil aggregate to "swell", which decreased the soil infiltrability. The "swelling" strength in the Mg2+ solution was much weaker than that in the Na+ solution, and the experimentally observed infiltrability values in Mg2+ were much higher than that in Na+ for soil with the same non-breaking aggregates. Conclusions: Soil infiltrability was determined by the electrostatic interactions at the soil/water interfaces, which was generated from the net surface charges of soil particles. The net force between soil particles can be repulsive because of the strong electrostatic repulsion, which results in aggregate breakdown and low infiltrability of soils. [ABSTRACT FROM AUTHOR]