Green-Ampt Infiltration Model Research Articles

GIS and cellular automata based slope rainwater movement process model and its application

Rainfall serves as a significant factor contributing to slope stability challenges in mountainous areas, and simulating the process of slope rainwater movement is a crucial approach for analyzing the stability of slopes triggered by rainfall. By combining computer numerical simulation technology with traditional hydraulic and hydrological calculation theories, it is possible to create an efficient and precise rainwater movement model that can simulate and analyze the process of rainwater movement on slopes. Utilizing natural slopes as the focal point of our research, the cellular automaton method was applied to simulate rainfall runoff on slopes, and a Cellular Automata (CA) based model for rainwater movement process was developed. This model modified the Green-Ampt (G-A) infiltration model by adopting an elliptical water content curve and introducing a coefficient that quantifies the ratio of saturated to unsaturated depth. Additionally, we refined the rules governing runoff generation and convergence within the slope and on its surface, enabling a comprehensive simulation of the entire rainwater movement process on the slope. Furthermore, the effectiveness of the model was validated through analytical solutions derived from simplified assumptions, laboratory experiments on infiltration and runoff in the flume, and a case study of a natural slope. The results show that the infiltration calculation results of the rainwater movement model are closer to the experimental values, and their overall values are slightly higher than the measured values, which are basically consistent with the model test results; The runoff calculation results show a phenomenon of initially increasing and gradually approaching the measured values compared to the measured values. When applying the model to an actual slope, it was found that the model comprehensively accounts for the influence of slope seepage, infiltration and runoff process, has better performance compared to G-A modified model. The model can be used to describe the spatial distribution and temporal variation of infiltration and runoff processes.

Application of a simplified Green-Ampt model to the Maga earthfill dam under rainfall conditions: A sensitivity analysis case of an infiltration model

The present paper applies a simplified Green-Ampt (GA) infiltration model for the numerical modelling of seepage processes within the body of the Maga earth dam, located in the Far-North Cameroon, under rainfall conditions. The parametrization approach makes possible the predictions of infiltrations parameters for various textures that constitute the body of earth dam and its vicinities. The effects of soil texture, permeability coefficient, rain intensity and initial moisture on infiltration rate and cumulative depth are investigated using numerical simulations carried out by running an Excel VBA code. A proposed optimization procedure of the literature is then used to improve the GA model parameters and accuracy of predictions. A case sensitivity analysis of the infiltration model parameters has also been made. Initial and saturated water contents, rain intensity and permeability coefficient at saturation have been identified as the most influents parameters for the model predictions, with obvious interactions between inputs. The contribution of main effects and interactions of above inputs ranges between 68.8 % and 90.03 % of the total variance. Comparisons of numerical results with the experimental ones obtained from the literature on real cases of simulated rainfall on main sub-Saharan soils have been done. The results show that numerical simulations underestimated 60 % and 56.25 % of the hydrodynamics parameters respectively for one and four simulated rain-sequence with relative errors (RE) ranging between −76.22 % and 300.25 %. The most representative results were obtained for 53.13 % of the predicted hydrodynamics parameters with RE value ranging between −23.90 % and 12.75 %. The obtained results proved that, the simplified GA model exhibited an acceptable accuracy in predicting seepage processes for ferruginous and degraded vertic soils. Therefore, the present study contributes to understand the role of numerical simulations tools in modelling and predicting subsurface phenomenon as seepage, for areas with high floods risks in a context of significant climate changes.

Stability analysis of rainfall-induced landslide considering air resistance delay effect and lateral seepage

Accumulation landslides are prone to occur during the continuous infiltration of heavy rainfall, which seriously threatens the lives and property safety of local residents. In this paper, based on the Green-Ampt (GA) infiltration model, a new slope rainfall infiltration function is derived by combining the effect of air resistance and lateral seepage of saturated zone. Considering that when the soil layer continues to infiltrate after the saturation zone is formed, the air involvement cannot be discharged in time, which delays the infiltration process. Therefore, the influence of air resistance factor in soil pores is added. According to the infiltration characteristics of finite long slope, the lateral seepage of saturated zone is introduced, which makes up for the deficiency that GA model is only applicable to infinite long slope. Finally, based on the seepage characteristics of the previous analysis, the overall shear strength criterion is used to evaluate the stability of the slope. The results show that the safety factor decreases slowly with the increase of size and is inversely correlated with the slope angle and initial moisture content. The time of infiltration at the same depth increases with the increase of size and slope angle, and is inversely correlated with the initial moisture content, but is less affected by rainfall intensity. By comparing with the results of experimental data and other methods, the results of the proposed method are more consistent with the experimental results than other methods.

A modified Green-Ampt infiltration model for muddy water

The Green-Ampt infiltration model has been widely used because of its simple structure and clear physical meaning of the parameters. The model parameters were improved using the equivalent saturated hydraulic conductivity to develop the Green-Ampt infiltration model for muddy water (MWGA). A saturated soil column infiltration test with muddy water was conducted to determine the influence of the soil texture (sandy soil and silt loam) and the sand content (S = 3 %, 6 %, 9 %, and 12 %) on the hydraulic conductivity of saturated soil columns. The equivalent saturated hydraulic conductivity was derived based on several assumptions and under different conditions. Eight one-dimensional vertical infiltration tests were conducted under the same conditions for verification. The MWGA was simplified according to the results, and four tests with different sand contents (S = 4 % and 10 %) were conducted to validate the MWGA for both soils (the simplified infiltration model was used for the sandy soil). The results indicated that the hydraulic conductivity trend of the saturated soil column during the infiltration of muddy water into sandy soil was in accordance with the physical model. The hydraulic conductivity of the silt loam was only influenced by the sand content and showed a significant linear relationship with the sand content. The root mean square error (SRMSE) obtained from the validation test under the same conditions was close to 0, and the absolute value of the relative error (SRE) was less than 15 %, indicating a good fit. The results of the validation tests for different sand contents showed that the simulated and observed values were close to the 1:1 line, demonstrating high model accuracy. Our results provide new insights into the infiltration of muddy water and the mechanism of reducing the infiltration rate due to the dense layer formed on the soil surface.

Modeling bioinfiltration surface dynamics through a hybrid geomorphic-infiltration model

Abstract Bioinfiltration systems are an increasingly prevalent mechanism for urban stormwater mitigation. One major challenge for the sustainability of bioinfiltration systems is erosion and channelization due to high bed shear stresses developed during large storm events. Sedimentation within these systems could also impact their performance as fine sediment may clog pathways necessary for infiltration. Understanding the geomorphology, shear stress, and sediment flux in the system can help predict maintenance needs associated with erosion and deposition. The current study introduces a framework for addressing this problem by combining a sediment transport model, FaSTMECH, with the Green-Ampt infiltration model. A comparison of observed and predicted ponding depths shows very good agreement (median Nash–Sutcliffe efficiency coefficient = 0.93) and demonstrates the ability of this novel framework in predicting the hydraulics and morphology within a bioswale bioinfiltration system. The framework introduced in this study opens the door to understanding sediment transport dynamics within a bioswale, which has the potential to advance planning and design to minimize impacts due to excessive erosion or deposition within bioswale bioinfiltration systems.

Evaluating Model Effectiveness for Soil Infiltration Attribute: Comparison of Green-Ampt, Horton and Modified Green-Ampt Infiltration Models

Soil infiltration is a very important concept in hydrology as well as irrigation, which plays a vital role in estimating surface runoff and groundwater recharge. It is a complicated process that varies with numerous factors. Accurate estimation of soil infiltration is required for future irrigation, and many other purposes. To estimate the infiltration process, there are numerous models. The majority of them have some presumptions, a unique calculation method, and some limitations. The purpose of the paper was to assess the model’s performance for a similar hypothetical scenario involving soil infiltration. It compared the infiltration rate, runoff rate, and incremental infiltration versus time for three different infiltration models: the Green-Ampt model (GA), the Horton model and the Modified Green-Ampt (MGA) model. A spreadsheet was used to calculate the Horton model, and HYDROL-INF (V 5.03) was used to simulate the other two models. Among those three models, the MGA model outperformed those three models, while the GA model produced greater infiltration rate than rainfall, which was insensible. The study showed that the MGA model, which provides useful infiltration predictions, outperformed the other two infiltration models. Since the Horton model does not consider ponding conditions, it is only applicable when the effective rainfall intensity exceeds the final infiltration capacity. Moreover, the GA model’s initial infiltration rate is irrational because it disregards the intensity of the rainfall. The results of this study will assist in selecting the most accurate method for estimating soil infiltration for agricultural purposes.

Analysis of Influencing Parameters of the Improved Model for Rainfall Infiltration in Unsaturated Tailings Soil

The rainfall infiltration analysis method is an important method for slope stability forecast and prevention. Slope angle and unsaturated soil layers are not shown in the conventional Green-Ampt (GA) infiltration model. In this paper, based on the GA model of rainfall infiltration in tailings slopes, two aspects of slope angle and the proportion of the transition layer of the wet layer are modified. The rainfall infiltration test of unsaturated tailing soil was conducted using a self-developed large-size tailing slope model test device. The results of GA model, improved GA model, and Richards’ equation calculation model are compared. The results show that the difference between the three models is small in the free infiltration stage, but the infiltration rate is lower than that of the GA model. With the gradual increase of rainfall time into the ponding infiltration stage, the expansion depth and infiltration rate of the wetting front of the improved GA model and Richards’ equation are greater than those of the GA model. The difference between the GA model and the improved GA model and Richards’ equation for the extended depth of wetting front increases with the increase of rainfall duration, while the difference of infiltration rate changes in the opposite trend. The results of the improved GA model and Richards’ equation to calculate the expansion depth and infiltration rate of wetting fronts are consistent, and the difference basically tends to stabilize with the increase of rainfall ephemeris. The results of the improved GA model are closer to the measured data, which can provide a reference for analyzing the rainfall infiltration pattern of open pit tailing dams and slope stability research. On the basis of the improved GA model, the influence of slope angle, rain intensity, initial water content, and saturation infiltration coefficient on rainfall infiltration was analyzed, and the analysis of parameter sensitivity indexes showed that slope inclination and initial water content had a greater influence on the model.

Study on the stability analysis of rainfall slope based on G-A model considering moisture content

In this paper, the moisture content on the wetting front is obtained by using the Van Genuchten (VG) model of unsaturated soil, and then the distribution of moisture content in the upper part of the wetting front is simplified as a trapezoid. The Green-Ampt (G-A) infiltration model of infinite slope with unsaturated characteristics is derived. The analytical expression of safety coefficient (FOS) of infinite slope with rainfall is solved by combining the limit equilibrium method with the unsaturated soil shear strength theory phase. The results show that: 1) compared with the traditional G-A model and the combined rectangular and 1/4 oval model, the upper part of the wetting front is simplified to a trapezoidal model, which has great advantages in infiltration rate and cumulative infiltration, especially when the slope is large or the rain intensity is heavy; 2) since the distribution of soil moisture content above the wetting front is considered, the matrix suction at the wetting front is not neglected, and the safety coefficient calculated by the method proposed in this paper is closer to the actual situation than the traditional G-A model.

A Comparative Analysis of Infiltration Models for Groundwater Recharge from Ephemeral Stream Beds: A Case Study in Al Madinah Al Munawarah Province, Saudi Arabia

Groundwater recharge is strongly influenced by the infiltration process. In this research, the Philip, Horton, Kostiakov, and Green–Ampt infiltration models were tested for the ability to describe the infiltration process in the ephemeral stream beds located in Al Madinah Al Munawarah Province in Saudi Arabia. Infiltration data were obtained from double-ring infiltrometer tests in 14 locations distributed over the province. The method of least squares through an objective function optimization formalism is utilized to estimate the parameters of each model. The results show high variability in the parameters of each model over the tests. Individual tests showed that some models were better for representing specific tests than other models. On average, the Kostiakov empirical model was the best at describing the 14 infiltration tests with only 2 empirical parameters, since it had the minimum root mean square error (RMSE) for the cumulative infiltration depth F (1.13 cm), and it also had the same RMSE for the infiltration rates f (0.1 cm/min), similar to other models. Moreover, the Kostiakov model had an acceptable correlation coefficient R = 0.61 for f, and R = 0.99 for F. The results imply significant variability in the groundwater recharge rates from flash floods in the region.

Reconstruction of the severe drought events of 1875-1879 in Shanxi Province, China, based on rain and snow record data from the Qing Palace Archives

Climate change is one of the main reasons for frequent severe droughts in many areas of China. At present, there is a lack of research on the occurrence and impact of large-scale and long-lasting extreme drought events in the historical period. This study utilized the ‘Yu-Xue-Fen-Cun’ (rain and snow record) data from the Qing Palace Archives for the Qing Dynasty and records from modern meteorological stations as data sources, combined with key parameters of the study area obtained by field experiments. The improved Green-Ampt infiltration model was used to convert historical data into precipitation data, and the precipitation anomaly percentage (PA) was calculated as a meteorological drought indicator. The spatial distribution and evolution of historical extreme drought events in Shanxi Province were studied and are discussed. The results show a severe shortage of rainfall followed by severe drought events between 1875 and 1879 in Shanxi Province. The shortage level reached its peak in 1877. Extreme drought events occurred from 1875 to 1877 when the whole province was heavily drought-stricken, with annual PA values of -65%, -64%, and -70%, respectively. Reconstructing extreme historical droughts has an important practical significance in coping with drought catastrophes that may occur now or in the future and contributes to the development of disaster prevention and preparedness strategies, disaster reduction policies, and risk prevention and control.

Implementation of the Green-Ampt Infiltration Model: Comparative between different numerical solutions

The phenomena of infiltration and the percolation of water in the soil are of fundamental importance for the evaluation of runoff, groundwater recharge, evapotranspiration, soil erosion and transport of chemical substances in surface and groundwater. Within this context, the quantitative determination of the infiltration values is extremely important for the different areas of knowledge, in order to evaluate, mainly the surface runoff. Several types of changes in vegetation cover and topography result in significant changes in the infiltration process, making it necessary to use mathematical models to assess the consequences of these changes. Thus, this article aims to implement the Green-Ampt model using two numerical methods - Newton-Raphson method and W-Lambert function - to determine soil permeability parameters - K and matric potential multiplied by the difference between initial and of saturation - comparing them to the real data obtained in simulations using an automatic rainfall simulator from the Federal University of Goiás - UFG. The Green-Ampt model adjusted well to the data measured from the rain simulator, with a determination coefficient of 0.978 for the Newton-Raphson method and 0.984 for the W-Lambert function.

Study on the influence of infiltration on flood propagation with different peak shape coefficients and duration

Abstract Traditional flood simulations fail to properly consider the impact of soil infiltration in floodplain areas with high soil infiltration rates. Notably, ignoring soil infiltration will lead to considerable uncertainty in flood simulations. In this paper, a fully hydrodynamic model coupled with the Green–Ampt infiltration model was used. Taking a natural reach in northern China (HTH in this paper) as a case study, observed flood discharge data were used to analyze the influence of soil infiltration on flood propagation based on the flood propagation simulation results for various inflow conditions. The maximum difference of inundation area is about 25%. The results show that soil infiltration has little effect on the inundation area during the rising stage of a flood. In the late period of a flood, the inundation area considering the effect of infiltration is smaller than that without infiltration, and the smaller the peak coefficient is, the longer the flood duration is, the larger the impact of infiltration on the inundation area. When the peak shape coefficient is 0.42 and the flood duration is 44.4 h, the maximum difference of the inundation area is about 28%. The research results provide a reference for flood management and post-disaster rescue efforts.

Effect of urban underlying surface change on stormwater runoff process based on the SWMM and Green-Ampt infiltration model

Abstract The acceleration of urbanization has brought significant changes to the urban underlying surface. As a result, the flood disaster caused by stormwater runoff has become increasingly prominent. The infiltration function of the permeable area can lead to flood disasters, but the extent and depth of the effect are still unclear. Therefore, based on the storm water management model (SWMM) and Green-Ampt infiltration model, this paper discussed the effect of improving soil saturated hydraulic conductivity (SSHC) and soil capillary suction head (SCSH) on the stormwater runoff process. The results show that the increase in SSHC and SCSH can significantly reduce runoff and increase infiltration. However, the improvement of SSHC can more effectively alleviate flood disasters compared with the improvement of SCSH. The change of SSHC has a significant effect on the stormwater runoff with a critical SSHC value while the effect can be ignored. In addition, there is a cross value; when the value of SSHC and SCSH is larger than the cross value, the difference between SSHC and SCSH in reducing runoff duration no longer exists. The critical value and cross value are not constant but change with the change of rainfall intensity.

Progressive Failure Analysis of Slope Water Damage Based on Improved Green-Ampt Infiltration Model

In order to get the law of rainwater infiltration and the law of progressive water damage, the slope of Tianshang bridge foundation in Yunnan Province of China is taken as the engineering basis. The site investigation of the damaged slope is carried out. The traditional Green-Ampt model is improved by considering the ponding effect of dynamic water flow on the slope surface. Based on the variation characteristics of wetting front obtained by the improved infiltration model, the progressive failure process of slope with continuous infiltration is simulated by FLAC3D software. The results show that the water damage of Tianshang bridge slope is mainly caused by the slope absorbing a lot of rainwater in a short time, which has obvious time discontinuity characteristics in time, and shows obvious multi-layer progressive failure characteristics in failure space. The wetting front characteristics obtained by the improved Green-Ampt infiltration model are more consistent with the engineering practice. The water accumulation effect of surface water gradually weakens with the increase of the wet front depth. The slope failure develops gradually from the toe to the top and from shallow to deep. The intermittent failure characteristics provide surplus time for the engineering treatment, the gravel soil slope should be treated after a small-scale water damage occurs.

Shallow slope stability evolution during rainwater infiltration considering soil cracking state

Cracks in a shallow slope will increase soil infiltration capacity and sequentially affect slope stability. To further understand the evolutionary characteristics of shallow slope stability caused by rainwater infiltration considering desiccation crack extension states, a series of analyses are conducted. The ponding infiltration characteristics of rainwater in a slope at different crack extension states are analyzed based on the Green-Ampt infiltration model. The evolution of slope stability under infiltration considering the crack expansion state is discussed under non-ponding infiltration and ponding infiltration. For the unsaturated infiltration case, an increase in both soil infiltration capacity caused by cracking and rainfall intensity will cause the slope to evolve toward an “unstable” state. The factor of safety (FS) gradually approaches the threshold FS0, which is mainly controlled by soil strength parameters, bulk density, and slope inclination. Under ponding infiltration conditions, the soil cracking degree will affect water migration and further affect slope stability evolution. The crack developmental state and rainfall conditions will affect the slope water saturation state during rainwater infiltration and further affect the evolution characteristics of the factor of safety at different depths.

Applicability of SWMM for semi Urban Catchment Flood modeling using extreme Rainfall Events

Urban floods are different type of flooding event as compared to normally occurring riverine floods which is very often seen along the river banks during heavy rainfall in monsoons. Continuous human interventions in natural vegetative land for rapid Urbanization activities has given rise to Urban Flooding. So, there is a need for capacity analysis of existing storm networks and identification of overflow locations is the need of the study. Hence, in the present study an attempt has been made to simulate Urban Flood scenario for a semi Urban catchment using Storm Water Management Model (SWMM). The whole area is divided into 20 sub catchments and the data acquired from 2017 rainfall events is used for modelling. The study area is represented in SWMM by the help of Master Plan AutoCAD maps having drain lines and Reduced Levels (R.L.s) information. From this detailed elevation information of various nodes and length of pipe lines has been estimated to make the schematic view of the study area in SWMM. The focus of the present study is to model runoff conditions using Dynamic wave method of flood routing and Green-Ampt Infiltration model in SWMM. The results showed that SWMM has capability to model and interpret flows at various channel sections and nodes for mitigating floods. Due to unavailability of gauged flow data the model Parameters needs calibration for more reliable results. Model has effectively given catchment responses for peak flow and volume of runoff which is considered as one of the essential components of Urban drainage planning to mitigate the risk of flood.

SCS Curve Number and Green-Ampt Infiltration Models

AbstractSoil Conservation Service curve number (SCS-CN) and Green-Ampt (GA) infiltration models are probably the most applied equations in practical hydrology to compute the amount of direct runoff...

A Generalized Analytical Solution for Preferential Infiltration and Wetting

Core Ideas New model simulates relative infiltration and wetting depth due to preferential flow. Solution normalizes parameters to account for soil properties and initial conditions. Preferential flow estimations match closely with dual‐permeability HYDRUS‐1D results. Preferential flow wetting depths decrease as volume of macropore domains increase. Model provides new insight into preferential flow dynamics during rainfall events. Macropores induce preferential flow in many soils, creating the need for parsimonious solutions to describe nonequilibrium infiltration and wetting processes. This study applied the Green–Ampt infiltration model within a dual‐domain framework to distinguish water movement through the soil matrix vs. through macropores. Using a nondimensional parameter set to generalize the results, the developed equations enabled estimates of infiltration and depth of wetting due to preferential flow during constant‐intensity rain. The analysis revealed that infiltration partitioning varies with time, with flow regimes changing at time of ponding of the matrix and again at time of ponding in the macropores. The results also showed that the fraction of infiltration due to preferential flow increases as a function of rainfall and relative volume of the macropore domain. Conversely, macropore volume has an inverse relationship with wetting depth: all other factors being equal, infiltration due to preferential flow becomes proportionally greater than matrix infiltration as macropore volume decreases. Finally, the proposed infiltration and wetting equations were compared with numerical simulations of the Richards equation for dual‐permeability soils. The analytical solutions closely approximated the numerical results, with root mean square deviation values ≤0.15 and simulated wetting depths within 35% of one another, even as modeled times to ponding varied by 5 to 80%. Altogether, the theoretical framework developed in this study provides new insight into preferential flow dynamics during rainfall events.

An Approximate Explicit Green–Ampt Infiltration Model for Cumulative Infiltration

Core Ideas Proposed an explicit Green–Ampt model (EGA model) to estimate cumulative 1D vertical infiltration. The form of error term ε is determined as a power‐function through non‐dimensional numerical analysis. The EGA model is reliable for estimation the cumulative infiltration for a variety of soil textures. Accurately estimating soil moisture infiltration information contributes to scientific understanding of the one‐dimensional (1D) vertical infiltration process. Because of its simple form, the Green–Ampt (GA) model has been extensively employed to simulate soil infiltration processes. However, the GA model is an implicit solution that must be solved through iterative techniques, and thus is inconvenient. Therefore, based on the two‐parameter infiltration equation proposed by Valiantzas, by adding an error term and non‐dimensional numerical analysis, this study proposes an approximate explicit Green–Ampt model (EGA model) for estimating cumulative infiltration with a determined power function expression for the error term. A total of 12 typical soils were selected from the USDA soil textural classes, and the 1D vertical soil infiltration process was simulated using Hydrus‐1D. The reliability of the proposed EGA model was verified using measured and simulated values. The mean absolute percentage relative error (MAPRE) and percentage of bias (PB) were taken as evaluation indicators to compare the estimated cumulative infiltration with the measured and simulated values. The results revealed that all cumulative infiltration values estimated by the EGA model are in good agreement with those measured in laboratory experiments and simulated using Hydrus‐1D; the mean MAPRE and PB values of all treatments were 4.2 and 0.7%, respectively. In addition, the estimated errors of the EGA model were consistent with those of the GA model. Hence, the EGA model can estimate the cumulative infiltration in 1D vertical soil infiltration with high accuracy and is suitable for a variety of soil textures.

Solution to Green–Ampt infiltration model using a two-step curve-fitting approach

Infiltration is an important hydrological process affecting the runoff, groundwater recharge and solute transport process. The Green–Ampt (GA) model, describing one-dimensional infiltration process, yields an implicit equation for estimation of cumulative infiltration with time. In this paper, an explicit approximation to the GA model is derived using two-step curve-fitting technique. The Marquardt’s algorithm is employed for least-squares estimation of nonlinear parameters. Performance of the proposed model is compared with the implicit GA model using numerical and published field experimental data. The quantitative statistical indicators namely, percent relative error (RE), maximum absolute percent relative error (MARE), percent bias (PB), and Nash–Sutcliffe modeling efficiency (E), are used to assess the performance of the proposed model. The solution of the proposed model matched very well with that of the implicit GA model with MARE ≤ 0.146%, PB ≤ 0.070%, and E value approximately equal to 1 for both the dimensionless numerical and dimensional field experimental infiltration estimates. Simulation results of the proposed model demonstrated the capability of the derived model in estimating infiltration rate and cumulative infiltration accurately and can be applied to solve variety of real-life hydrological problems.