Water Infiltration Process Research Articles

From Rockfall Observation to Operational Solutions: Nearly 20 years of Cryo-gravitational Hazard Studies in Mont-Blanc Massif

The enhanced rockfall frequency (V > 100 m3) first noticed in the European Alps, has motivated investigations on high mountain rock walls and rock wall permafrost since the 2000s. Mont-Blanc massif (MBM) has become a pilot study area thanks to the wealth of data and knowledge on rockfall and permafrost dynamics acquired through successive research projects. Statistical analysis of rockfall distribution (> 1300 events inventoried between 2007 and 2021) shows that they are related to permafrost distribution and increasing atmospheric temperature, opening promising perspective for developing forecasting tools to support mountain practitioners in their risk mitigation strategy. However, understanding how rock wall destabilizations develop is challenged by the variety of potentially involved thermo-hydro-mechanical processes. To face these challenges, research currently carried out in the MBM focuses on water infiltration and circulation processes in frozen rock walls by combining advanced numerical modelling approaches and ad hoc field surveys. The coupling of models simulating heat and water transport with geoelectrical imaging methods could allow assessment of ground water/ice distributions and contents that is highly relevant for geotechnical purposes. Concurrently, the combination of acquired data and knowledge in integrative approaches of landscape changes and hazards involving permafrost degradation, glacier retreat, possible lake formation and rock wall destabilization appears as an essential basis for land-planning concerns. Finally, thermal and hydrological interactions between rock wall permafrost and ice bodies nestled on rock faces (ice aprons and hanging glaciers) is another direction of research to be pursued with cross-disciplinary implications.

Study on Water Vertical Infiltration Characteristics and Water Content Simulation of Sandstone Overlying Loess

Research on the infiltration characteristics of surface water is fundamental for understanding the entire hydrological process. Therefore, studying the water infiltration process of sandstone slopes overlaid with loess and predicting soil moisture content are of great importance for investigating hydrological processes and controlling soil erosion in the hilly and gully areas of the Loess Plateau in China. This study mainly focuses on the simulation of the vertical water infiltration characteristics and water movement patterns of four kinds of sandstone (feldspathic and argillaceous sandstone) structures covered with thin layers of loess. In the one-dimensional vertical infiltration experiment and Hydrus-1D model simulation, the interlayer transition planes of loess–feldspathic and loess–feldspathic–argillaceous sandstones were found to present two conditions: fine soil covering coarse soil and coarse soil covering fine soil. Therefore, water infiltration reduced permeability. The existence of a transition layer between loess and feldspathic sandstone decreased the water infiltration rate and infiltration amount and decelerated the speed of the wetting front, thereby further affecting the ability of water infiltration. By using the Hydrus-1D model, 15 sets of soil hydraulic parameters, including θx (0.028–0.05795 cm3/cm3), θs (0.2306–0.4786 cm3/cm3), α (0.01899–0.06071 cm−1), n (1.438–6.408), and Ks (1.96·10−4–0.0576 cm/s) were inverted and optimized for each 20 cm soil layer (total of 60 cm). The Van Genuchten model constructed using these parameters demonstrated high accuracy in the simulation of water content in the vertical infiltration process of sandstone covered by loess with the coefficient of determination R2 > 0.849 and relative error RE < 5.311.

Evaluation of loess-filled slope failure triggered by groundwater rise using a flume test

Gully Stabilization and Highland Protection (GSHP) are useful in preventing gully erosion and have been widely utilized in the Loess Plateau of China. Groundwater rise is an important factor that can lead to loess-filled slope instability. A flume device was designed to study the process of water infiltration into a loess-filled slope and the subsequent failure process of the slope due to groundwater rise. The loess was uniformly infiltrated with water, resulting in preferential seepage via the development of cracks in the slope from settlement deformation. The pore-water pressure increased in the front of the slope and decreased at the back during slope failure, due to contraction in the slope toe and increased tensional at the back of the slope. The failure process of the slope can be divided into three stages, settlement deformation and collapse deformation with vertical displacement during slope settlement, and slope toe slide-flow or regressive failure with a primarily horizontal displacement in the direction of the slope’s free surface. The factors of suffusion erosion, saturated softening, and infiltration dynamics during water infiltration into the loess-filled slope promote slope failure according to experimental data and numerical simulations.

A Deep Learning-Based Approach for a Numerical Investigation of Soil–Water Vertical Infiltration with Physics-Informed Neural Networks

The infiltration of water into the soil can lead to slope instability, which is one of the important causes of many geological hazards (such as landslides and debris flows). Therefore, the numerical investigation of the soil–water infiltration process provides the prerequisite for the determination of slope stability, which is of great significance for geological hazard prevention. In this study, we propose a deep learning-based approach for a numerical investigation of soil–water vertical infiltration with physics-informed neural networks and perform a comprehensive evaluation and analysis of the soil–water infiltration process in different soil types. In the proposed approach, the partial differential equation for soil–water infiltration is combined with the neural network based on physics-informed neural networks (PINNs) to obtain numerical analysis of the soil–water infiltration process. The results indicate that (1) compared with the traditional numerical method, the PINN-based method for the numerical investigation of soil–water vertical infiltration proposed in this study has a smaller error and can obtain more accurate numerical results. (2) During vertical infiltration of water in the different soil types, the light loam is the fastest, the heavy-loam the second and the medium loam the slowest. medium-loam soils are less susceptible to water infiltration of the three soil types and are more suitable for the filling of artificial slopes and dams. The proposed approach could be employed for the simulation of soil–water infiltration processes, not only for the discrimination of slope stability under rainfall conditions, but also for the selection of artificial slopes and dams to fill soil to prevent slope instability.

Effects of moss biocrust on soil water infiltration in the Three Gorges Reservoir Area, China

We examined the effects of moss-dominated biocrusts on soil infiltration properties in Wangjiaqiao watershed of the Three Gorges Reservoir Area. Five levels of coverage (1%-20%, 20%-40%, 40%-60%, 60%-80% and 80%-100%) were set, with a nearby bare land as the control. We collected soil samples and conducted infiltration process observation by double cutting ring method. The results showed that biocrusts could appreciably increase soil cohesion, porosity, clay content, water-stable aggregates and organic carbon of topsoil, but significantly reduce soil bulk density and sand content. Biocrusts promoted soil water infiltration, with the initial infiltration rate (Ii), stable infiltration rate (If), average infiltration rate and cumulative infiltration amount being two times or more of that in bare land. Withbiocrust coverage increasing, soil infiltration properties firstly increased and then decreased, and peaked at 40%-60% coverage level. Results of path analysis indicated that Ii was mainly affected by biocrust coverage, soil bulk density, and organic carbon content, while If was mainly affected by biocrust coverage and soil bulk density. The simulation results of four infiltration models demonstrated that Horton model was the best fitting on the water infiltration process of biocrusted soil in the Three Gorges Reservoir Area.

Study on Soil Water Infiltration Process and Model Applicability of Check Dams

As the primary ecological construction measure on the Loess Plateau, check dams play an essential role in developing agricultural production, improving people’s production and life, and replenishing groundwater. Soil water infiltration is the most important way to replenish groundwater in the dam land. In order to investigate the water infiltration process of check dams, an empirical model suitable for the simulation of the dam land infiltration process was selected. The soil water infiltration process of the check dam was studied by a field test and a model simulation. The results showed that there were few macropores in the dam, and the water mainly moved downwards in the form of matrix flow. Moreover, the stable infiltration rate of the dam site was low, and its infiltration process could be divided into three stages: rapid infiltration, fluctuating infiltration, and stable infiltration. In addition, the infiltration rate of a non-silted dense layer was 2.4~5 times that of a silted dense layer. The Horton model had a good fitting effect on the water infiltration process of the check dam and thus was suitable for the simulation and prediction of the water infiltration process of the dam. The results can provide a theoretical basis for efficient soil water utilization and infiltration simulation of check dam land.

Wetting Front Velocity Determination in Soil Infiltration Processes: An Experimental Sensitivity Analysis

An experimental approach for measuring the wetting front velocity in soils during water infiltration processes is presented. This experimental research is developed to test the sensitivity of the measurement technique in the detection of differences in the dynamics of the wetting front advancement in different soil testing scenarios. Experimental scenarios include undisturbed and artificially compacted soils, square and circular cross-sections of soil samples, water flowing in both directions downward and horizontal, and water infiltration in a block soil sample. The measurement technique is based on wetting front detection employing moisture sensors that measure the soil’s electrical conductivity. The technique was able to detect differences in wetting front in contrasting scenarios. Two-dimensional wetting front advancement experiments carried out on a block sample confirmed the results obtained for the one-dimensional case.

Border Irrigation Modeling with the Barré de Saint-Venant and Green and Ampt Equations

In gravity irrigation, how water is distributed in the soil profile makes it necessary to study and develop methodologies to model the process of water infiltration and redistribution. In this work, a model is shown to simulate the advancing front in border irrigation based on the one dimensional equations of Barré de Saint-Venant for the surface flow and the equation of Green and Ampt for the flow in a porous medium. The solutions were obtained numerically using a finite difference Lagrangian scheme for the surface flow and the Raphson method for the subsurface flow. The model was validated with data obtained from the literature from an irrigation test and its predictive capacity was compared with another model and showed excellent results. The hydrodynamic parameters of the soil, necessary to obtain the optimal irrigation discharge, were obtained through the solution of the inverse problem using the Levenberg–Marquardt optimization algorithm. Finally, the results found here allow us to recommend that this model be used to design and model border irrigation, since the infiltration equation uses characteristic parameters of the physical soil.

Biochar effects on soil properties, water movement and irrigation water use efficiency of cultivated land in Qinghai-Tibet Plateau

Biochar, has recently, been widely used as a potential soil additive to improve the quality of cultivated land. However, the effect of biochar on irrigation water use efficiency (IWUE) remains unclear in the Qinghai-Tibet Plateau (QTP). Therefore, the purpose of this study was to explore the effects of biochar on the soil properties, water infiltration, and irrigation water efficiency of QTP cultivated land. A column experiment with four biochar application levels (0, 3, 6, and 9 kg·m−2 denoted CK, BC1, BC2, and BC3, respectively) was conducted to explore the biochar effect on the soil water infiltration process. The soil bulk density (γ), saturated water content (θs), soil water retention curve (SWRC), specific water capacity C(h), and saturated hydraulic conductivity (Ks) were measured after the trial. The effects of biochar application level, biochar application depth, irrigation water depth, and initial soil moisture on water loss and IWUE were then simulated by HYDRUS-2D. The results showed that biochar slowed the process of soil water infiltration by changing the soil physical properties and hydraulic properties, reducing the water loss by 5%–15.02%, effectively alleviating the waste of irrigation water, and therefore increasing IWUE by 2%–9.43%. Water loss and IWUE were significantly associated with the biochar application depth and level. Additionally, a biochar level of 6 kg·m−2 showed the best effect for ameliorating the QTP's cultivated soil. These results provide a novel approach for reducing water loss and enhancing the irrigation water use efficiency of QTP cultivated soil.

Sentinel-2 images to assess soil surface characteristics over a rainfed Mediterranean cropping system

Soil surface characteristics (SSCs) are of high importance for water infiltration processes in crop fields. As SSCs present strong spatiotemporal variability influenced by climatic conditions and agricultural practices, their monitor has already been explored by using UAV images and multispectral remote sensing. However, each technique has encountered difficulties characterizing this spatiotemporal variability. The objective of this work was to explore the potential of Sentinel-2 images to assess three SSCs – the green vegetation fraction, dry vegetation fraction and physical soil surface structure – at several dates. This work explored two approaches for classifying these three SSCs from five Sentinel-2 images acquired from August to November 2016. In the “single-date” approach, a Random Forest Classifier (RFC) model was trained to classify one SSCj from a dataset extracted from one Sentinel-2 image i (model noted RF_sdi,SSCj). In the “multi-date” approach, a RFC model was trained to classify one SSCj from a dataset extracted from the five Sentinel-2 images (noted RF_mdSSCj). The classification analysis showed that i) the RF_sdi,SSCj and RF_mdSSCj models provided accurate performances (overall accuracy > 0.79) regardless of the studied SSCj and the tested Sentinel-2 image, ii) the RF_sdi,SSCj model did not allow the classification of SSC classes that were not observed on the studied date, and iii) the RF_mdSSCj model allowed the classification of all SSC classes observed in the five Sentinel-2 images. This indicated that several Sentinel-2 images can favourably be used to increase knowledge of spatiotemporal representation of SSCs by extending results of infrequent, localized and cumbersome field work.

Combining FDR and ERT for monitoring soil moisture and temperature patterns in undulating terrain in south-eastern Norway

The occurrence of freeze–thaw cycles modifies water infiltration processes and surface runoff generation. Related processes are complex and are not yet fully investigated at field scale. While local weather conditions and soil management practices are the most important factors in both runoff generation and surface erosion processes, local terrain heterogeneities may significantly influence soil erosion processes in catchments with undulating terrain.This paper presents a field-based investigation of spatial and temporal heterogeneities in subsurface soil moisture and soil temperature associated with freezing, thawing, and snowmelt infiltration. The field setup consists of a combination of traditional point measurements performed with frequency domain reflectometry (FDR) and electrical resistivity tomography (ERT). The transect was approximately 70 m long and spanned an entire depression with a north-facing slope (average slope of 11.5%) and a south-facing slope (average slope of 9.7%). The whole depression was entirely covered with stubble.Observed resistivity patterns correspond well to the measured soil moisture patterns. During the observation period, the north facing slope froze earlier and deeper compared with the south facing slope. Freeze–thaw cycles were less pronounced in the north-facing slope than in the south-facing slope. There were also differences in soil temperature and soil moisture patterns between lower and upper parts of the monitored depression. These indicate that initiation and development of runoff related processes, and consequently soil erosion, in regions with freeze–thaw cycles may differ significantly depending on local terrain characteristics. Consequently, it indicates that spatial terrain heterogeneities, especially slope aspects, may be important when studying soil erosion processes, water flow and nutrient leaching in lowlands where patchy snowpacks and dynamic freeze–thaw cycles are predominating.

Conversão de taxa de infiltração de água em solo com e sem cobertura vegetal usando o modelo de Kostiakov-Lewis

ABSTRACT Soil water infiltration rates are essential for hydrological studies, planning and design of irrigation and drainage systems, among other applications. Various studies have been carried out in plots with and without vegetation cover, aiming to identify the influence of the cover on the water infiltration process in soil. However, a few works have addressed the relationship between infiltration rates of a plot with and without vegetation cover. Here we investigated the ability to iterate between infiltration rates with and without vegetation cover, seeking to identify potential correlations. We propose an innovative and easy-to-use empirical model that allows the conversion of infiltration rates in systems with vegetation cover into infiltration rates without coverage and vice versa. Altogether, we used a dataset comprising 142 rainfall simulation experiments under plots with and without cover, including 6 different types of soil and 18 types of land cover and management. The proposed model was based on the Kostiakov-Lewis model, presenting performance similar to other infiltration models, which is effective in a variety of planting and vegetation cover systems.

Effects of hydro-mechanical material parameters on the capillary barrier of reinforced embankments

This paper presents a numerical analysis of the water infiltration process in embankments reinforced with permeable geosynthetics. An emphasis is given to the study of the capillary barrier permanence at the soil-geotextile interface. For the analysis, an infiltration-deformation coupled model is used, and the numerical results are validated with experimental data. The proposed model properly describes the main characteristics of the capillary barrier phenomenon observed experimentally. A parametric analysis is performed to investigate the effects of the initial void ratio (e0), overconsolidation ratio (OCR), initial shear elastic modulus (G0), coefficient of compressibility (λ), anisotropy of the hydraulic conductivity (kr), initial suction (ψi), and water retention curve parameters (α and n′) on the performance of the capillary barrier during a rain infiltration process. Finally, a statistical analysis is carried out to evaluate the parameters that have influence on the development of pore water pressure (PW). The implemented infiltration-deformation coupled model shows the effect of the hydraulic parameters on the development of the capillary barrier -as commonly considered in conventional analysis- as well as the effect of the mechanical parameters of the soil and geotextile. The overall results highlighted the capability of the model, in combination with statistical analyses, to capture the complexity of the capillary barrier development in reinforced soil structures.

Occurrences of Deep-Seated Creeping Landslides in Accordance with Hydrological Water Storage in Catchments

Rainfall is one of the most important triggers of both shallow debris flows and deep-seated landslides. The triggering mechanism involves the process of water infiltration into the failure zone. For deep-seated landslides, the deeper and more extensive failure surfaces delay the effect of the process and thus delay landslide initiations. The delay is difficult to assess, especially if the sites only have scarce or insufficient monitoring data. Under these circumstances, we illustrate that the occurrences of landslides can be estimated by their correlations with the phenomenological water storage index (WSI) of a given catchment. In the present study, a total of five deep-seated landslides in TienChih (4) and SiangYang (1) are investigated. The displacements of the landslides were recorded by global positioning system (GPS) and the WSI was modelled using the tank model. The result demonstrates that the WSI correlates closer in time to the landslide motion than the rainfall, and the WSI thresholds for the landslides are inferred. Thus, this technique can be applied as an associated method to evaluate landslide initiation.

Infiltration process of irrigation water in oasis farmland and its enlightenment to optimization of irrigation mode: Based on stable isotope data

The transmission of water through soil is one of the critical links to reflect the hydrological process. At present, there are controversies about the infiltration of farmland irrigation water and the replacement of old and new water in arid areas, which significantly reduces the scientific nature of the irrigation policy formulation. In this study, we monitored the temporal and spatial changes of stable isotopes of soil water in Minqin Oasis farmland, analyzed the infiltration process of irrigation water, used the MixSIAR isotope mixture model to estimate the contribution of irrigation water to soil water and evaluated their effective contribution time to different soil layers. This study suggests that: The temporal and spatial changes in pore water isotope reflect the process of artificial irrigation and evaporation. Within 5 days after irrigation, the average contribution rate of irrigation at 0–20 cm, 20–60 cm, and 60–100 cm soil layers was 31.11 ± 17.74%, 19.17 ± 12.72%, and 31.56 ± 12.42%, respectively. Under the influence of soil water content, topography, and plastic film cover, the effective contribution time of irrigation water to 0–20 cm and 60–100 cm soil layers was more than 5 d, and the effective contribution time to the 60–100 cm soil layer is only 4 d. The research results will help understand the hydrological process of farmland in the arid oasis area and provide a scientific basis for improving agricultural irrigation mode, which will help realize the sustainable development of regional agriculture.

Numerical investigation of heat transfer and water infiltration characteristics within two-dimensional granular packed beds

This study used numerical analysis to determine the transport phenomena of hot water infiltration in a two-dimensional granular packed bed. The present study aims to investigate the parameter that affects the water saturation and temperature distribution in the two-dimensional porous packed bed. For this purpose, the problem was solved numerically using two-dimensional unsaturated flow and heat transfer models of hot water infiltration. Novel studies on the simultaneous heat and moisture transfer during hot water infiltration in partially saturated porous materials were investigated. The study illustrated the characteristics of heat and moisture transfer during the water infiltration process in various testing conditions. The results of the numerical model were validated with the results from previous research. It was found that the water flux supplied, and particle size have significant effects on the distribution of water saturation and temperature in the packed bed. The water saturation and heating area of the fine particles tended to expand in the lateral direction faster than the downward direction. The increase in supplied water flux resulted in a deeper and larger zone of water saturation and heating area. Furthermore, the heating area was found to be expanding slower than the water saturation front in all conditions.

Effects of crude oil pollution on soil moisture infiltration with loessial soil and aeolian sandy soil

Crude oil may block soil pores, affect soil water repellency, and change soil water movement. In this study, soil column simulation was used to study the effects of different crude oil pollution levels (0, 0.5%, 1%, 2%, 4%) on the water infiltration processes in loessial soil and aeolian sandy soil. The results showed that soil wetting front speed and infiltration rate of those two soils decreased with increasing crude oil content. The time needed for wetting front reaching the bottom of the soil column was the longest under 4% crude oil polluted soil, which was 4 times and 48 times longer than that of no crude oil polluted soil for loessial soil and aeolian sandy soil, respectively. The cumulative infiltration of loessial soil decreased with increasing crude oil content, while it increased to the max and then decreased as the crude oil content increased in aeolian sandy soil. The cumulative infiltration curves of aeolian sandy soil with high crude oil contents (2% and 4%) presented "up-tail" phenomenon. Kostiakov infiltration model and Philip infiltration model could better fit the infiltration process than Green-Ampt model for loessial soil with different crude oil content. However, the two models could only well fit the infiltration process for aeolian sandy soil with low crude oil content (0, 0.5%, 1%). Crude oil pollution could significantly affect soil water infiltration process, especiall in aeolian sandy soil.

Investigation of the hydraulic conductivity of an unsaturated compacted bentonite/claystone mixture

A pre-compacted MX80 bentonite/Callovo-Oxfordian (COx) claystone mixture has been proposed as a candidate sealing material in a French deep geological repository for high-level radioactive waste. An in-depth understanding of the hydraulic property of this material is essential for accessing the over-pack corrosion and nuclide migration along the gallery. In this study, water flow in the compacted bentonite/claystone mixture was investigated by carrying out infiltration and water retention tests under constant-volume conditions alongside detailed microstructure observation. The evolution of total water hydraulic conductivity with suction was experimentally determined based on the instantaneous profile method. It was observed that the measured total hydraulic conductivity increased slowly at high suctions, then quickly at low suctions and finally approached the saturated value. A new method was developed based on the evolving pore structure, accounting for both vapour and liquid-water hydraulic conductivities. The total hydraulic conductivity predicted by the proposed method agreed well with the measured value, indicating the reliability of the predictive method. The vapour hydraulic conductivity was larger than the liquid-water one at a suction larger than 15·2 MPa, while liquid-water hydraulic conductivity became dominant at a suction lower than 15·2 MPa. In addition, based on the predicted vapour and liquid-water hydraulic conductivities, a numerical model was set up to simulate the water infiltration process. Comparison between the simulation and the measurement showed close agreement, validating the two-phase water flow mechanism in the bentonite/claystone mixture.

Band application of flue gas desulfurization gypsum improves sodic soil amelioration

Blending flue gas desulfurization (FGD) gypsum with surface sodic soil is a universally recognized method for the rapid amelioration of sodic soils; however, little information is available on whether other application methods (band application) will reclaim sodic soil. Three FGD gypsum application methods (single-band, dual-band and blend applications) and a control treatment (non-FGD gypsum) were carried out using sodic soil in soil bins to investigate the effects of the application method on the wetting front, major cations in the leachate during the process of water infiltration and soluble and exchangeable cations in the soil profile after infiltration. The results showed that the wetting fronts in the band treatments were denser in the horizontal direction than in the vertical direction, but the blend and control treatments only had vertical migration. The main channel of the stream in the band treatment was concentrated below the application site of FGD gypsum. The orders of desalting capacity were blend treatment, dual-band treatment and single-band treatment for the same volume of outlet water. There was no water outflow in the control treatment even after 115 days of leaching. The dual-band treatment significantly decreased the soil sodicity of the 0–40 cm soil profile, while the single-band treatment only effectively reclaimed (horizontally) half of the soil. In the blend treatment, the exchangeable sodium percentages were 21.3 % and 34.7 % at depths of 30–35 cm and 35–40 cm, respectively, and were close to zero at a depth of 0–30 cm. Compared with blend treatment, band application could be a better way to reclaim sodic soil with FGD gypsum due to its advantages of long-term and efficient amelioration with low consumption.

Contribution of root decay process on soil infiltration capacity and soil water replenishment of planted forestland in semi-arid regions

Large-scale afforestation has seriously aggravated the consumption of soil water and caused soil desiccation and even the dry soil layers, which has been restricting the survival and sustainability of vegetation in semi-arid areas. How to solve soil water deficit reasonably is an important practical problem we are facing. Here, a field experiment of the decayed roots with different times on soil water infiltration processed was conducted in planted forestland by a double-ring infiltration instrument, to determine the contribution of decayed tree roots on soil water infiltration process and replenishment. Results showed that the decayed process of tree roots in forestland could significantly reduce root density (RD) and increase the relative porosity improved by the roots (RPIR) (P < 0.05). The macropore formed by root decay could not only significantly increase the infiltration rate at each stage (P < 0.05), but also reduce the decrease rate of infiltration rate. Compared with bare land, the decayed roots of the 1–4 yr, the 5–8 yr, and the 9–12 yr increased the amount of soil water replenishment by 37.12%, 217.52%, and 259.85%, respectively. Overall, the decayed tree roots could maintain a relatively high and stable infiltration rate by reduced root density, which increased the effective replenishment of soil water of dry soil layers in forestland. These findings have potential implications for understanding the effect of decay process of tree roots on soil water replenishment, and provide a theoretical basis for the solution to dry soil layers and sustainable management of forestland in semi-arid areas.