Water Infiltration Process Research Articles

Water Permeability of Kemafil Georopes with a Geotextile Core Made of Wool Waste Based on Laboratory and Field Tests

This paper presents the results of laboratory and field tests on the hydraulic properties of georopes produced using the Kemafil technology from sheep wool waste generated in the textile industry. The laboratory tests included the determination of the basic physical parameters and filtration properties of georopes, as well as tests of the physical properties and water permeability of the experimental training ground. As part of the field research, measurements of water infiltration through 1.0, 2.0 and 5.0 m long georopes embedded in the ground were carried out in nine monthly cycles. The conditions of water flow through the georopes were monitored on the basis of georope resistance measurements. Numerical calculations were also performed to determine the conditions of water flow through the georopes and the process of water infiltration from the georopes into the ground. The laboratory tests have shown that the water permeability of georopes is high and, based on the filtration criteria, they can act as a drainage material. The field measurements showed that the resistance of the georopes changed over time and depended on the amount of water supplied and the absorbency of the ground. The results of the numerical calculations were consistent with the results of the field measurements, at the same time indicating that some water infiltrated into the ground in the vicinity of the georopes, meaning that under the conditions that prevailed during the experiment, the georopes can act as infiltration drainage systems in the ground.

Impact of textural layers in soils on irrigation infiltration processes in an oasis farmland, northwestern China

AbstractThe Hexi Corridor Oasis in China is an important agricultural area supported by extensive irrigation. The sandy soil in the area exhibits textural layering, which has marked effects on its properties. Textural layered soils play an important role in distributing and regulating water regimes in irrigated fields. However, little is known about the textural layering‐dependent variability in soil water infiltration characteristics following irrigation and the potential effects on soil hydrology and water regimes in these soils. The objective of this study was to determine water infiltration processes and their influencing factors for six soil profile types in an oasis farmland. Six in situ constant‐head infiltration measurements (with three replications in each of six sites) were conducted with a single‐ring infiltrometer in different soil texture configurations, and Hydrus‐2D model was applied to evaluate soil water distribution. The results showed that the wetting front depth for all treatments was in the following order: ST‐1 > ST‐5 > ST‐6 > ST‐3 > ST‐2 > ST‐4; the stable infiltration rate ranged from 1.2 to 3.3 cm/min during the investigation period in all treatments. The presence of a finer‐textured soil layer decreased water infiltration rates through the profiles, and the thickness and burial depth of textured layers had obvious effects on infiltration, compared with homogeneous sand profiles. Presence of a medium‐textured layer affected the infiltration characteristics and soil water spatial variability; driven by increased field capacity and the wilting point, hydraulic conductivity was correlated with soil variables that were related to soil structure, such as wilting point and field capacity, and less so with variables that were related to soil texture, such as the clay fractions (p < 0.001). These results suggested that textural layering altered the soil structure and caused heterogeneous infiltration of water, with implications for the distribution of irrigation water and prevention of deep percolation in this oasis farmland. The result of this study offers a new analysis of ponded single‐ring water infiltrometer data that the soil water infiltration is also influenced by the type of textural layered than just the irrigation system, which supports crop irrigation management in study area and other regions with similar soil regimes.

Contribution of root and soil properties on soil infiltration capacity of gramineous and leguminous forages during root decomposition

Soil properties are generally altered during root decomposition, which impacts soil water infiltration. Gramineous and leguminous plants present distinct root properties, but it remains unclear whether the root or soil properties are primarily responsible for the soil infiltration capability during root decomposition. To identifythe differences in the contributions of root and soil properties to soil infiltration capability between these two species during root decomposition, a potted plant in situ decomposition experiment was conducted using Bothriochloa. ischaemum (Gramineae) and Lespedeza. davurica (Leguminosae) during three root decomposition times (the 90th, 270th and 450th day). The results revealed that all the root properties (root length, root volume, average root diameter and root biomass) gradually decreased during root decomposition, especially the root length (RL) and root volume (RV) of L. davurica in 0–40 cm soil layer, with reductions of 55.35% and 58.73% at the 450th day compared with the 90th day. The reverse was true for the soil porosity and mean weight diameter of the soil aggregates. Compared to B. ischaemum, L. davurica presented relatively high initial infiltration rate (IIR), steady infiltration rate (SIR), and average infiltration rate (AIR) values at three root decomposition times. A great increase in the soil infiltration rate was observed for both species at the late decomposition stage (450th day), especially for L. davurica, with increases of 38.32%, 267.7%, and 137.1% in IIR, SIR, and AIR. The GLM analysis results revealed that root properties had a greater contribution to the soil infiltration capability. The key factors controlling the soil water infiltration process have been quantified as RL and RV. The present study indicates that leguminous forage presented greater soil infiltration capability during root decomposition. A great decrease in RL and RV within the upper soil layers increased the soil porosity and facilitated the formation of soil aggregates, thereby promoting water flow and ultimately improving the soil infiltration capability.

Modification of Green-Ampt model based on multi-stage characteristics of soil water infiltration

ABSTRACT Water infiltration in unsaturated soil is significantly affected by multi-stage characteristics that depend on the movement of the wetting front. We modified the Green-Ampt model to accurately capture these multi-stage characteristics during infiltration. The proposed model divides the water-infiltrated unsaturated soil into three zones, while the infiltration process itself is divided into three stages, with the quarter-elliptic wetting front curve being defined. The proposed model, together with other Green-Ampt based models, is analysed and compared with experimental investigations conducted in this study, as well as with published results from the literature. The results demonstrate the proposed modified model successfully describes the measured infiltration time for soil columns with different heights. Additionally, a parametric sensitivity analysis of the proposed model reveals the water infiltration process is mainly controlled by the hydraulic conductivity in the infiltrated zone and the suction head between the wetting front zone and the unpenetrated zone.

Multifactor analysis of the infiltration characteristics of film hole irrigation under muddy water conditions

Film hole irrigation under muddy water conditions is a new and effective water-saving irrigation technology. In order to determine the influence of multiple factors on the infiltration process of film hole irrigation under muddy water conditions, 12 sets of indoor infiltration tests were conducted to investigate the effects of four key influencing factors (muddy water sand content, hole diameter, soil bulk density, and infiltration time) on the infiltration characteristics of irrigation with film holes under muddy water conditions, in this study. Based on the experimental data, accurate and effective soil water infiltration and vertical and horizontal wetting front transport models were constructed. Based on the modeling results, the standard regression coefficients of each influencing factor against the fitted parameters were calculated and the effects of the factors on the fitted parameters were analyzed. Error analysis showed that both models could effectively simulate the soil water infiltration process under experimental conditions. Infiltration time was the dominant factor influencing the cumulative infiltration per unit of film hole area, followed by hole diameter, muddy water sand content and lastly, soil bulk density. Infiltration time was also the main influencing factor of the vertical wetting front transport distance, followed by soil bulk density, muddy water sand content, and lastly, hole diameter. Similarly, infiltration time exerted the greatest effect on the horizontal transport distance, followed by hole diameter, soil bulk density and muddy water sand content. The model validation revealed that both the calculated and measured values were distributed around the 1:1 line, reflecting the accuracy of the models. The results of this study can provide theoretical support for the design of film hole irrigation systems under muddy water conditions.

Effects of gravel on the water infiltration process and hydraulic parameters of stony soil in the eastern foothills of Helan Mountain, China

The investigation into the impact of gravel on water infiltration process and hydraulic parameters in stony soil could offer a theoretical basis to enhance water availability in rocky mountain area. A one-dimensional vertical infiltration experiment was used in this study. Six groups of gravel content of 0% (CK), 10% (W1), 20% (W2), 30% (W3), 40% (W4) and 50% (W5) were established to explore the changes in the wetting front, cumulative infiltration volume and infiltration rate. Then the accuracy of four infiltration models in simulating soil water infiltration processes was evaluated. Finally, Hydrus-1D was used to perform numerical inversion of the soil water content after infiltration. The findings revealed that: (1) When the infiltration time reached 300 min, the wetting front of the W1, W2, W3, W4 and W5 treatments was 11.00%, 17.00%, 32.25%, 38.75% and 54.50% lower than CK, the cumulative infiltration volume was 29.80%, 38.97%, 45.62%, 54.74% and 73.17% lower than CK, and the stable infiltration rate was 50.98%, 52.94%, 66.67%, 68.63% and 86.27% lower than CK. (2) The soil–water infiltration processes were accurately described by the Horton model, the coefficient of determination (R2) > 0.935. (3) The simulation results of Hydrus-1D showed that with the increase of gravel content, the values of the retention water content (θr), saturated water content (θs), shape coefficient (n) and saturated hydraulic conductivity (Ks) were decreased, the values of the reciprocal of air-entry (α) were increased. The value of R2 was more than 0.894, the root mean square error (RMSE) and mean absolute error (MAE) were less than 2%, which demonstrated that the Hydrus-1D model exhibited superior capability in simulating the changes of water content in stony soil in rocky mountain area. The findings of this study demonstrated that gravel could decrease the water infiltration process and affect the water availability. It could provide data support for the water movement process of stony soil and rational utilization of limited water resources in mountainous area.

The structural evolution of undisturbed loess due to water infiltration

Loess structure is the physical key factor that determines its stability and consists of macro-pores, loose texture, and water sensitivity. The structural change characteristics and effects of the undisturbed loess before and after water infiltration are studied using mechanical CT and simulation tests in order to study the structural change process within the undisturbed loess caused by water infiltration. The change in particle state is as follows: the peak frequency point of the equivalent diameter of the loess particles after infiltration ranged from 16.75 to 23.76 μm, and the eroded fine particles consisted primarily of fine particles. The smaller loess particles are removed by water infiltration resulting in coarsening of soil particles. The sphericity of the loess particles gradually changes from spherical pores to angular and dendritic pores. The particle inclination angle transitions to a range greater than 70°, and its proportion is approximately 61%. The change in pore structure is as follows: The loess porosity after infiltration increased by approximately 20%, and the increase in the pore area ratio of the mesopores and the macropores was higher than that of the micropores. Additionally, the small pores increased by more than 5 times the original state of the undisturbed loess. The connected pores expanded less than 60% of the initial state to more than 90% after infiltration, thus, increasing the dominant seepage channel of the undisturbed loess. These changes in particle and porosity further increase the water filtration intensity and promote the migration of fine particles (mainly silt particles), linking loess catastrophes and are the leading cause of loess settlement and slope instability. The process of water infiltration into the loess, the mechanism of loess collapsibility, and the influence of salinity on the loess structure and strength are discussed in this study.

Laboratory and numerical simulations of infiltration process and solute transport in karst vadose zone

Groundwater in karst systems is a vital resource, which is often highly vulnerable to contaminants that infiltrate through the vadose zone. Understanding the processes of water and contaminant infiltration in the vadose zone is extremely important for protecting and managing karst water resources. A laboratory-scale physical model based on a typical conceptual model of the karst vadose zone was constructed to characterize the influence of the rainfall intensity and internal structure on the infiltration process and solute transport in the karst vadose zone under controlled conditions. Five factors, including the rainfall intensity, the surface slope, the degree of karstification, the thickness of the transfer zone, and the existence of epikarst, were considered in laboratory experiments. A corresponding lumped-parameter model was subsequently developed to further analyze and investigate the water and solute infiltration processes in the laboratory scale physical model. Recession- and breakthrough curves generated from the lab experiments and the water and solute loss from each reservoir generated from the simulation results were analyzed. The downward trend of breakthrough curves' peak value and the variation of solute loss's proportion in three rainfall events demonstrate that both the increase in thickness and karstification degree will intensify the buffer effect of the karst vadose zone, and this buffer effect is mainly affected by the slow flow system which can be inferred from the increasing percentage of cumulative discharge of slow reservoir (qS). With increasing karstification degree, the recession coefficient (α) exhibits opposite trends depending on the existence of epikarst or not, indicating the karstification degree has a more significant effect on hydraulic conductivity (K) when an epikarst is present while affecting effective porosity (φ) more noticeably in the absence of epikarst. The rainfall intensity affects the results of both experimental and numerical simulation most significantly. The percentage of discharge and solutes flowing from the slow reservoir (qS and msoil_S) have negative correlations with rainfall intensity, suggesting a greater influence on fast flow with increasing rainfall intensity.

Investigation on the behaviors of water infiltration in the unsaturated loess

Introduction: Surface water from precipitation or irrigation is the sole contributor to groundwater replenishment in the Loess Plateau of China. The occurrence of landslides in the Loess Plateau is closely related to the infiltration process of surface water, and the frequent occurrence of landslides in the Loess Plateau in recent years has seriously affected the economic development and security of the Loess Plateau.Methods: To investigate the loess infiltration in deeper soil, the process of moisture infiltration in unsaturated loess is studied by field observation, theoretical analysis, and numerical simulation.Results and discussion: The research results indicated that the interstitial flow in loess could be divided into three different zones: the active zone, the stable zone (2–94 m), and the saturated zone (below 97 m); based on the matric suction and water content calculations, the L1 soil stable water content is 24.4%, which corresponds to the moisture sensor measurement of L1 loess 4 m and 7 m of stable zone data; the numerical simulation results show that whether the infiltration is continuous or intermittent, the infiltration law is the same. After 20 years, there will be a stable water content zone in the 1–8 m soil layer with a water content of 31%. The numerical results well confirm the theoretical calculation results. The research results explain the process of surface water infiltration into groundwater through thick loess and can provide an important reference for the prevention and control of geological disasters caused by water infiltration in loess areas.

The Impact of Land Cover Density on the Water Infiltration Process in the Nyadeng Lake Area, Merabu Village Berau District, East Kalimantan

The sustainability of water resources depends on the state of the nearby forest. Land cover is essential for sustaining life systems in a region; the higher the quality of the land cover or forest vegetation, the greater the biodiversity value of the region. This research attempts to determine whether or not the vegetation in the Merabu Village area of Nyadeng Lake has the capacity to process the infiltration rate. The vegetation was sampled using simple random sampling, and a 20 m x 20 m plot was used to represent the area under investigation. Data collection was accomplished by establishing research plots that can represent the entire area or research area, with the size of the plot varying according to plant class. This research utilized a total of six plots. Three plots on the west and three on the east were laid out at a distance of five meters from the lake’s shore. The infiltration rate was measured by creating 0.5 m x 0.5 m infiltration subplots with five replicates per sample plot. These locations have been established approximately five metres away from the shore of the lake. High vegetation cover has a tremendously positive effect on infiltration. The coefficient of determination, with a value of 72%, indicates that the infiltration ability is influenced by the existence of vegetation to a significant degree.

Mapping Capillary Infiltration-Induced Potential in Water-Triggered Electric Generator Using an Electrical Probe Integrated Microscope.

Power generation from water-triggered capillary action in porous structures has recently geared extensive attention, offering the potential for generating electricity from ubiquitous water evaporation. However, conclusively establishing the nature of electrical generation and charge transfer is extremely challenging arising from the complicated aqueous solid-liquid interfacial phenomenon. Here, an electric probe-integrated microscope is developed to on-line monitor the correlation between water capillary action and potential values at any desired position of an active layer. With a probe spatial resolution reaching up to fifty micrometers, the internal factors prevailing over the potential distribution across the whole wet and dry regions are comprehensively identified. Further, the self-powered sensing capabilities of this integrated system are also demonstrated, including real-time monitoring of wind speed, environmental humidity, ionic strength, and inclination angle of generators. The combination of electric potential and chemical color indicator suggests that charge generation is likely correlated with ion-selective transport in the nanoporous channel during the water infiltration process. And unipolar ions (for instance protons) should be the dominant charge-transfer species. The work reveals the fundamental principles regulating charge generation/transfer during the water-triggered electric generation process.

No-Tillage System Can Improve Soybean Grain Production More Than Conventional Tillage System.

Soil management systems can directly interfere with crop yield via changes in the soil's physical and hydraulic properties. However, short- to medium-term experiments of conduction do not always demonstrate the modifications of the management systems in these properties. Thus, the aim of this study was to evaluate the physical properties of the soil in a long-term management system and to relate it to the storage and availability of water to plants, verifying its effect on soybean yield. The experiment was conducted in randomized blocks in a split-plot scheme with four replications. Plots were composed by soil management (conventional tillage and no-tillage), and subplots represented three soil depths (0.0-0.1, 0.1-0.2, and 0.2-0.4 m). The soil's physical and hydraulic properties, root development, and soybean yield were evaluated. The no-tillage system not only presented higher bulk density and soil resistance to compaction up to a depth of 0.2 m but also greater root development. This management also did not affect the process of water infiltration in the soil and presented an increase in soybean grain yield by 6.5%. The long-term no-tillage system (33 years) offers less risk of water stress to soybean plants; it contributes to greater grain yield of this crop when compared to the conventional tillage system.

Impacts of the soil pore structure on infiltration characteristics at the profile scale in the red soil region

The complexity and uncertainty of pore structures, hinder the understanding of the water infiltration process along a soil profile. In this study, soil pore structures quantified by X-ray computed tomography (CT) scanning and infiltration processes traced using stable hydrogen and oxygen isotopes were linked under three land uses (forestland, citrus land, and rainfed cropland) in the red soil region of southern China. Our results showed that 95% of the soil pore diameters in the surface layer (0–20 cm) in forestland, citrus land, and rainfed cropland were concentrated in the ranges of 0.05–2.46, 0.05–2.24 and 0.05–1.04 mm, respectively. Rainfed cropland had the most soil micropores, along with a high porosity and poor connectivity, while there were more large, well-connected tubular pore channels in the forestland and citrus land. Hydrogen and oxygen stable isotopes were effective in tracing soil water infiltration processes under saturated and near-saturated conditions. The soil infiltration depths of citrus land, forestland, and rainfed cropland were 45, 40, and 25 cm, with "new water" volumes of 37.2, 26.4, and 22.3 mm, respectively. CT-based porosity and the soil texture were considered crucial indicators in the evaluation of the exchange between “old water” and “new water” during infiltration processes. More specifically, the soil structure of the limiting layer not only controlled the infiltration rate but also played an extremely important role in the infiltration mechanism, reflected by the different ratios of “new water”. The soil pore characteristics mainly affected soil water transport, while other soil properties played more important roles in soil water retention.

Variation of interception efficiency and transformation to natural glucocorticoids in three texture reclaimed water receiving riverbeds

BackgroundThe efficacy of the interception and purification mechanism for low-dose toxic contaminants in riverbeds, which serve as a link between surface water and groundwater, is of paramount importance in ensuring groundwater safety, particularly considering the replenishment of reclaimed water. The specific objective of this work is to identify the variation of interception efficiency and transformation to natural glucocorticoids in three texture reclaimed water receiving riverbeds. MethodsHerein, an experimental percolation platform was set up to simulate hydrocortisone (HC) migration and biotransformation during the reclaimed water infiltration process through three typical types of riverbeds (silty clay (SC), loam (L) and sand (S)). Significant findingsThe attenuation of HC in time dimension and longitudinal direction was consistent with the two compartment first-order kinetic model, with decay rate constant greater than -0.031 m−1 and 2.71 d−1 in spatial and temporal distribution. The SC riverbed enhanced 36.36 % HC removal due to adsorption and microbial transformation. Furthermore, the major metabolic pathways of side chain oxidation and ring rupture were significantly enhanced due to the increasing diversity and relative abundance of the functional bacteria present in SC. The enrichment of functional genera, Stenotrophomonas and Sphingomonas contributed to the biotransformation enhancement. pH and TOC played the most significant role to the difference of migration and metabolism of HC. Moreover, pore volume was the primary factor leading to varying adsorption of three types of riverbeds for HC. The simulation results with HYDRUS showed that the ecological risk level of HC in L and S were 6.5 times higher than SC after 50 years infiltration. Therefore, future challenges and prospects concerning pollution control and enhancement measures should be pay attention to the physicochemical characteristics of various riverbeds.

Irrigation Salinity Affects Water Infiltration and Hydraulic Parameters of Red Soil

Unconventional water resources (e.g., saline water, etc.) for irrigation as a promising supplementary water source can alleviate the freshwater shortage in the agriculture of red soil areas in Southern China. It should be noted that the presence of soluble salt in this water source may have detrimental influences on soil water infiltration and crop growth. Understanding the effect of unconventional water irrigation (UWI) on water infiltration in red soil is important. Previous studies have shown that the salinity of UWI can alter soil hydraulic properties to change soil water movement in saline soils. However, the underlying mechanism and factors of water infiltration in red soil under UWI with different salinity levels remain limited. Therefore, a laboratory experiment (one-dimensional vertical infiltration experiment and centrifuge method) was conducted to evaluate the effect of UWI with different salinity levels [0 (the distilled water, CK), 1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g L−1] on the soil water infiltration process, soil water characteristic curve (SWCC), soil water constants estimated using the SWCC, saturated and unsaturated hydraulic conductivity (KS and K) as well as the soil chemistry of soil profile [pH, electrical conductivity (EC), and Na+ and Cl− contents]. The primary factors of soil water infiltration were identified using stepwise regression and path analysis methods. The results showed that UWI salinity decreased water infiltration by 1.53–7.99% at the end of infiltration in red soil, following the order of CK > S1 > S5 > S2 > S3 > S10. Moreover, UWI could enhance soil water availability with an increase of 8.55–12.68% in available water capacity. In contrast, lower KS and K were observed in S1–S10, and there was a negative linear relationship between irrigation salinity and KS. UWI also produced the EC, Na+, and Cl− accumulations in the soil profile. As the salinity level of UWI increased, the accumulations aggravated. Soil acidification was found in S1–S5, while soil alkalization was observed in S10. Additionally, α, PWP, and KS were the primary factors influencing the water infiltration of red soil. This study can help optimize the soil infiltration model under UWI and establish a foundation for unconventional water management in the red soil regions of Southern China and other similar regions. In addition, the undisturbed red soil under agricultural unconventional water irrigation and the long-term effect of unconventional water application should be considered.

A Study on Infiltration Characteristics and One-Dimensional Algebraic Model Simulation in Reclaimed Soil with Biochar

The cultivated land area in China is approaching the red line of farmland protection. The newly reclaimed land will become a vital reserved land resource, and it possesses a large exploratory potential. Newly reclaimed soil usually has low productivity with poor physical and chemical properties as well as weak fertility, and it is prone to serious soil erosion. The effects of corn straw biochar and rice husk biochar (at the mass ratio of 2%, 4%, and 8%) on the soil infiltration process and soil moisture distribution in the soil profile were studied. The results showed that the infiltration duration was prolonged, and the wetting front migration distance and infiltration rate were decreased under biochar addition treatments, except under the low addition rate for rice husk biochar. The Philip model and Kostiakov model accurately described the water infiltration process of the newly reclaimed soil with both kinds of biochar. The two kinds of biochar used in this study affected both the initial infiltration rates and stable infiltration rates, and water infiltration was more sensitive to rice husk biochar and its addition rate. The moisture in the soil profile after infiltration was simulated using a one-dimensional algebraic model. The surface soil moisture was improved with both kinds of biochar addition, and the water retention ability was enhanced with an increased biochar addition rate. In conclusion, corn straw biochar with a high addition rate is beneficial for inhibiting soil water infiltration and improving weak water retention ability in the newly reclaimed area, which is a recommended choice for efficient soil construction in newly reclaimed land.

Novel numerical model to simulate water seepage through segmental gasketed joints of underwater shield tunnels considering the superimposed seepage squeezing effect

The water leakage through segmental joint gaskets has become a major concern that adversely affects the normal serviceability of underwater shield tunnels throughout the construction and operational periods. Therefore, it is of great significance to investigate the sealing performances of the joint gaskets, which directly helps evaluate the waterproof capacity of underwater shield tunnels. To date, the numerical modeling plays an irreplaceable role in the analysis on the waterproof capacity of the joint gaskets. Nevertheless, conventional methods tend to ignore the self-sealing effect induced by the water seepage pressurization, thus failing to reveal the progressive evolution of the water infiltration process through the joint gasket. To remedy this defect, this paper proposed a novel numerical model to simulate the penetration process of the sealing gasket based on the Python language-enabled secondary programming in the ABAQUS software, which could fully consider the superimposed seepage squeezing effect. Based on the proposed model, the waterproof failure process and the dynamic contact stress of the gasket’s water seepage path subject to excessive hydraulic pressure were thoroughly investigated. Moreover, indoor tests on the waterproof capacity of the gasket were also performed to validate the proposed model. It is found that the numerical results from the developed model are consistent with the experimental results. This research will contribute to better understanding of the gaskets’ hydraulic penetration process and more accurate prediction of the maximum waterproof capacity in underwater shield tunnels.

Barometric pressure variation alters electrical resistivity during water infiltration in the vadose zone

To reveal the mechanism of the water–gas two-phase repulsion during water infiltration and its barometric pressure change and resistivity response in the vadose zone while it provides the basic theory for water resources evaluation and groundwater pollution, also provides technical support for the accurate interpretation of electrical resistivity tomography (ERT) application. Therefore, a research system based on laboratory experiments, numerical simulations, and ERT was established to determine the moisture transport pattern and the quantitative relationships between barometric pressure and resistivity. The results show that the intensity of the water infiltration process in the vadose zone meets the percolation theory. The barometric pressure will go through three stages when the infiltration intensity is higher than the critical value. The critical time of the barometric pressure variation shortens gradually with the infiltration intensity and medium permeability increase. In contrast, the maximum barometric pressure increases gradually with the rise in infiltration intensity and medium porosity. The layered-heterogeneous structure's effect depends on the underlying medium's properties. The trivial variation of resistivity responds to the barometric pressure variation. The quantitative relationship between the resistivity and the barometric pressure in the vadose zone is established by the difference between the measured value and the calculated value by improving Archie's formula. The resistivity reduction due to increasing barometric pressure can account for over 10.9% of the moisture effect. These insights provide technical support for ERT applications to eliminate barometric pressure's effect on resistivity and accurately identify the target medium.

Analysis of Water Infiltration Characteristics and Hydraulic Parameters of Sierozem Soil under Humic Acid Addition

The farmland in Yinchuan is composed of sierozem soil, which is characterized by high sand content and low organic matter content, resulting in poor water-holding capacity and weak soil structure. Humic acid is a natural organic polymer soil amendment. It is critical to study how humic acid affects soil water infiltration in sierozem soil at the microlevel. A one-dimensional vertical infiltration experiment was conducted to explore how adding different amounts of humic acid (0, 1%, 2%, 3% and 4%) affected the infiltration characteristics and hydraulic parameters of the sierozem soil. The results revealed that the wetting front and cumulative infiltration decreased with the increase in humic acid addition. When the infiltration time was 90 min, the wetting front of the 1%, 2%, 3% and 4% treatments was 6.50%, 10.00%, 15.00% and 21.00% lower than CK (0 for CK), and the cumulative infiltration volume was 4.50%, 11.14%, 18.42% and 23.60% lower than CK, respectively. Among the three infiltration models created by Philip, Horton and Kostiakov, the Kostiakov model (R2 > 0.95) could more accurately describe the soil water infiltration process in the study area. After infiltration, the moisture content of each soil layer increased with the increase in humic acid, which improved the water-holding capacity of the sierozem soil. Using Hydrus-1D to calculate soil hydraulic parameters, we found that the humic acid addition affected the hydraulic parameters. With the increase in the amount of humic acid addition, the retention water content θr and saturated water θs were positively correlated with the humic acid addition amount and negatively correlated with the saturated water conductivity Ks and the reciprocal of air-entry α. The results showed that humic acid could increase the water-holding capacity of soil and improve the rapid water loss and poor water-holding capacity of sierozem soil.

Sets of infiltration models for water infiltration in sustainable urban drainage systems

Infiltration is a crucial process in various fields such as hydrology, agriculture, urban soils, and particularly for Sustainable Urban Drainage Systems (SUDS) operation. Over the past century, the physics of infiltration has been extensively studied by developing models that estimate the dynamics of infiltration. In this study, three physically-based infiltration models (CH1, CH2, and CH3) have been developed as part of the Canoe Hydrobox (CH) platform, designed to simulate and evaluate the performance of SUDS. The three models rely on similar approaches to the Green-Ampt (GA) model by describing the water flux as the product of the equivalent hydraulic gradient and the equivalent hydraulic conductivity. The models differ in their ways of defining the hydraulic gradient and conductivity from the hydric conditions, soil parameters, and geometric features. The two first models (CH1 and CH2) consider an increase in the hydraulic conductivity with infiltrated water amount, whereas the last model (CH3) considers only the saturated hydraulic conductivity. For the hydraulic gradient, the first model considers the difference between the surface water pressure head and the height of infiltrated water. The other two models consider the difference between the surface water pressure head and the isostatic water pressure head at the surface in equilibrium with the height of infiltrated water. These models were applied to simulate water infiltration processes into dry, wet, and intermediate-wet soils. We compared these results with the numerical solution of the Richards equation using HYDRUS software. The comparison allowed the assessment of the capability of CH models to satisfy the critical principles of soil water infiltration. Subsequently we used the three models to invert six real experimental infiltration data to test their capability to work in inverse mode. The two models (CH1 and CH2) produced specific time-evolution of infiltration rates in disagreement with the physics of water infiltration under regular conditions (e.g., no water repellence). The third model (CH3) performed the best for both direct and indirect modes and is therefore considered as the best candidate. The CH3 model will be implemented in the new version of Canoe Hydrobox (CH) platform. This study provides a basis for further research into hydrological models for SUDS and their hydraulic performance.