A new approach for studying vertical infiltration

Soil Research ◽  
2020 ◽  
Vol 58 (5) ◽  
pp. 509
Author(s):  
Alexander Poulovassilis ◽  
Ioannis Argyrokastritis
Keyword(s):  
Hydraulic Properties ◽  
Pressure Head ◽  
Gradient Term ◽  
Infiltration Process ◽  
New Approach ◽  
Homogeneous Porous Media ◽  
Cumulative Infiltration ◽  
Head Gradient ◽  
Cumulative Curve ◽  
New Methodologies

The exact contribution of the pressure head gradient term during the vertical infiltration process, occurring in homogeneous porous media under zero ponding head, is determined analytically to advance the knowledge related to the infiltration phenomenon. This contribution is smaller than that of the horizontal infiltration by a factor at which is a measurable function of the infiltration time t, characteristic of each porous body. By adding to this contribution that of gravity, a new two-term analytical equation is formulated which exactly reproduces an available vertical cumulative curve and satisfies the physics governing infiltration process. The properties of at allow the derivation of an equation accurate for small and moderate t and of another one accurate for all t, including large values. By applying new methodologies, the values of the sorptivity and hydraulic conductivity are determined analytically from an available cumulative infiltration curve. Philip’s two-term equation, which does not satisfy the physical requirements at the upper extreme of t, and three other equations that do satisfy it, are examined in the light of the findings of the present work. The proposed equations are able to describe the vertical infiltration process and may be used to provide the hydraulic properties.

scholarly journals Infiltration under Ponded Conditions

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3492
Author(s):  
Ioannis Argyrokastritis ◽  
Maria Psychogiou ◽  
Paraskevi A. Londra
Keyword(s):  
Hydraulic Properties ◽  
Soil Surface ◽  
Pressure Head ◽  
Wide Range ◽  
Head Gradient ◽  
Actual Contribution ◽  
Simple Equations ◽  
Infiltration Processes ◽  
Hydrus 1D ◽  
Good Agreement

Ponded infiltration processes occur in agricultural lands irrigated by flooding of their soil surface or under insufficient drainage conditions. The existing equations describing the phenomenon of vertical infiltration under ponded conditions have not considered the actual contribution of the pressure head gradient to the flow. In this study, simple equations are proposed to describe the horizontal and vertical infiltration under various ponding heads incorporating the actual contribution of the pressure head gradient to the flow. Six soils with known hydraulic properties, covering a wide range of soil textures, were used. Horizontal and vertical infiltration data are obtained by numerical simulation for all soils studied using the Hydrus-1D code. To validate the accuracy of the proposed equations, the solutions of horizontal and vertical infiltrations provided by the proposed equations were compared with numerically simulated ones provided by the Hydrus 1-D. The analysis of the results showed a very good agreement in all soils studied. The proposed vertical infiltration equation was also compared to a simple and accurate equation which does not incorporate the actual contribution of the pressure head gradient to the flow and differences between them were observed in all soils studied.

scholarly journals Predicted Infiltration for Sodic/Saline Soils from Reclaimed Coastal Areas: Sensitivity to Model Parameters

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Dongdong Liu ◽  
Dongli She ◽  
Shuang’en Yu ◽  
Guangcheng Shao ◽  
Dan Chen
Keyword(s):  
Water Movement ◽  
Soil Surface ◽  
Coastal Areas ◽  
Model Parameters ◽  
Wetting Front ◽  
Sodic Soils ◽  
Infiltration Process ◽  
Infiltration Model ◽  
Soil Physical Quality ◽  
Cumulative Infiltration

This study was conducted to assess the influences of soil surface conditions and initial soil water content on water movement in unsaturated sodic soils of reclaimed coastal areas. Data was collected from column experiments in which two soils from a Chinese coastal area reclaimed in 2007 (Soil A, saline) and 1960 (Soil B, nonsaline) were used, with bulk densities of 1.4 or 1.5 g/cm3. A 1D-infiltration model was created using a finite difference method and its sensitivity to hydraulic related parameters was tested. The model well simulated the measured data. The results revealed that soil compaction notably affected the water retention of both soils. Model simulations showed that increasing the ponded water depth had little effect on the infiltration process, since the increases in cumulative infiltration and wetting front advancement rate were small. However, the wetting front advancement rate increased and the cumulative infiltration decreased to a greater extent whenθ0was increased. Soil physical quality was described better by theSparameter than by the saturated hydraulic conductivity since the latter was also affected by the physical chemical effects on clay swelling occurring in the presence of different levels of electrolytes in the soil solutions of the two soils.

Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

1996 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Axial Flow ◽  
Internal Flow ◽  
Pressure Head ◽  
Design Flow ◽  
Discharge Valve ◽  
Head Gradient ◽  
Axial Flow Pump ◽  
Flow Pump

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

Application of Artificial Intelligence Techniques for the Prediction of Infiltration Process

2018 ◽  
Author(s):  
Balraj Singh ◽  
Parveen Sihag ◽  
Abbas Parsaie ◽  
Anastasia Angelaki
Keyword(s):  
Good Prediction ◽  
Effective Parameters ◽  
Random Forest Regression ◽  
Infiltration Process ◽  
Good Prediction Performance ◽  
Cumulative Infiltration ◽  
Model Efficiency ◽  
Multi Linear Regression ◽  
Artificial Neural Network Ann ◽  
Kostiakov Model

Infiltration process was analysed using predictive models of Multi-Linear regression (MLR), Random Forest regression (RF), artificial neural network (ANN), M5P tree and their performances were compared with empirical model: Kostiakov model. These models were assessed using field dataset containing 340 observations. Field experimental data was implemented for training and testing the above models and their outcomes were assessed with the help of suitable performance assessment parameters. The RF based models performs batter than other models with Nash-Sutcliffe model efficiency (NSE) equal to 0.9963 and 0.9904 for the training and testing stages, correspondingly. ANN, MLR and M5P model also gives a good prediction performance. Sensitivity investigation suggests that the parameters, cumulative time and moisture content in the soil are the most effective parameters for the assessment of cumulative infiltration of soil..

scholarly journals Determination and Evaluation of the Parameters for the Green & AMPT Infiltration Equation in Some Agricultural Soils in Mexico

2016 ◽  
Author(s):  
Jorge Víctor Prado Hernández ◽  
Fermín Pascual Ramírez ◽  
David Cristóbal Acevedo ◽  
Mauricio Carrillo García ◽  
Antonio Martínez Ruíz
Keyword(s):  
Agricultural Soils ◽  
Pressure Head ◽  
The United States ◽  
Water Infiltration ◽  
United States Department ◽  
Good Representation ◽  
Wetting Front ◽  
Infiltration Process ◽  
Functional Relationships ◽  
Relative Errors

An adequate representation of the water infiltration process in the soil allows improving the efficiency in application and the uniformity in surface irrigation. The Green and Ampt model has shown a good representation of the process, and researchers from the United States Department of Agriculture (USDA) determined the values of their parameters for soils of that country, which are shown in tables or through functional relationships and this information is used as reference in several parts of the world, although there is no certainty that they are representative of the soils in Mexico. In this study, the parameters of the Green & Ampt equation were determined and evaluated in some soils of agricultural importance in Mexico. The parameters were obtained in four ways: one of them applied a methodology adapted from Brooks and Corey to quantify the wetting front capillary pressure head and used an permeameter under constant hydraulic head to determine the saturated hydraulic conductivity, and the other three consisted in taking them from three studies reported by the USDA. The values of the parameters suggested in Mexico drastically underestimated the results with relative errors (RE) in a range of -49.0 to -94.0% and the most representative were those obtained with the methodology proposed in this research with RE of -15.0 to 6.0%.

scholarly journals Spatial variability of soil hydraulic properties on a steep slope in the loess plateau of China

2008 ◽  
Vol 65 (3) ◽  
pp. 268-276 ◽  
Author(s):  
Wei Hu ◽  
Ming An Shao ◽  
Quan Jiu Wang ◽  
Jun Fan ◽  
Klaus Reichardt
Keyword(s):  
Spatial Structure ◽  
Spatial Variability ◽  
Loess Plateau ◽  
Spatial Dependence ◽  
Hydraulic Properties ◽  
Applied Pressure ◽  
Soil Surface ◽  
Pressure Head ◽  
Steep Slope ◽  
The Loess Plateau

The understanding of the structure of the spatial variability of soil surface hydraulic properties on steep slopes is important for modeling infiltration and runoff processes. The objective of this study was to investigate the spatial variability of these properties on a steep slope of the Loess Plateau in northwest China. A 9600 m² area was systematically sampled in a grid of 106 points spaced 10 m x 10 m. Hydraulic properties were determined with a disc infiltrometer under multiple pressure heads (-15, -9, -6, -3, 0 cm) at each sample point. Classical and geo-statistical methods were used for data analysis. The results indicated that the variation of Gardner's a and hydraulic conductivities at all applied pressure heads was moderate and the heterogeneity for hydraulic conductivities increased as the applied pressure head increased. Along the slope, hydraulic conductivities generally decreased downwards, while the Gardner's a fluctuated slightly. The Gardner's a of the shaded aspect of the slope was greater than that of the sunny aspect. The hydraulic conductivities of the shaded aspect were greater at higher pressure heads as compared to the sunny aspect, but lower than those of the sunny aspect at lower pressure heads. Correlation analysis showed a negative correlation between hydraulic conductivity and soil organic matter and clay (<0.01 mm) contents. Hydraulic conductivities at pressure heads of -3, -6, -9, -15 cm varied across the slope and their spatial dependence increased as the pressure head declined. The heterogeneity and spatial dependence of hydraulic properties were larger for the areas with shaded aspect as compared to the sunny aspect, however, as pressure decreased they showed a progressively increasing spatial structure, and their spatial structure behaved increasingly similar in both the shaded and sunny aspects.

scholarly journals Using Wastewater in Irrigation: The Effects on Infiltration Process in a Clayey Soil

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 968 ◽  
Author(s):  
Ammar A. Albalasmeh ◽  
Mamoun A. Gharaibeh ◽  
Ma’in Z. Alghzawi ◽  
Renato Morbidelli ◽  
Carla Saltalippi ◽  
...  
Keyword(s):  
Soil Water ◽  
Hydraulic Properties ◽  
Field Experiments ◽  
Overland Flow ◽  
Clayey Soil ◽  
Water Infiltration ◽  
Treated Wastewater ◽  
Water Drainage ◽  
Infiltration Process ◽  
Relevant Effect

Soil water infiltration is a critical process in the soil water cycle and agricultural practices, especially when wastewater is used for irrigation. Although research has been conducted to evaluate the changes in the physical and chemical characteristics of soils irrigated by treated wastewater, a quantitative analysis of the effects produced on the infiltration process is still lacking. The objective of this study is to address this issue. Field experiments previously conducted on three adjacent field plots characterized by the same clayey soil but subjected to three different irrigation treatments have been used. The three irrigation conditions were: non-irrigated (natural conditions) plot, irrigated plot with treated wastewater for two years, and irrigated plot with treated wastewater for five years. Infiltration measurements performed by the Hood infiltrometer have been used to estimate soil hydraulic properties useful to calibrate a simplified infiltration model widely used under ponding conditions, that were existing during the irrigation stage. Our simulations highlight the relevant effect of wastewater usage as an irrigation source in reducing cumulative infiltration and increasing overland flow as a result of modified hydraulic properties of soils characterized by a lower capacity of water drainage. These outcomes can provide important insights for the optimization of irrigation techniques in arid areas where the use of wastewater is often required due to the chronic shortage of freshwater.

scholarly journals Effects of the Grain Size on Dynamic Capillary Pressure and the Modified Green–Ampt Model for Infiltration

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yi-Zhih Tsai ◽  
Yu-Tung Liu ◽  
Yung-Li Wang ◽  
Liang-Cheng Chang ◽  
Shao-Yiu Hsu
Keyword(s):  
Grain Size ◽  
Capillary Pressure ◽  
Dynamic Effect ◽  
Pressure Head ◽  
High Flow ◽  
Model Parameters ◽  
Wetting Front ◽  
Grain Sizes ◽  
Cumulative Infiltration ◽  
Capillary Pressures

Darcy-scale capillary pressure is traditionally assumed to be constant. By contrast, a considerable gap exists between the measured and equilibrium capillary pressures when the same moisture saturation is considered with a high flow rate, and this gap is called the dynamic effect on the capillary pressure. In this study, downward infiltration experiments of sand columns are performed to measure cumulative infiltration and to calculate the wetting front depth and wetting front velocity in sands with different grain sizes. We estimate the equilibrium capillary pressure head or suction head at the wetting front using both the classical Green–Ampt (GAM) and modified Green–Ampt (MGAM) models. The results show that the performance of MGAM in simulating downward infiltration is superior to that of GAM. Moreover, because GAM neglects the dynamic effect, it systematically underestimates the equilibrium suction head in our experiments. We also find that the model parameters α^ and β of MGAM are affected by the grain size of sands and porosity, and the dynamic effect of the capillary pressure increases with decreasing grain size and increasing porosity.

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