Outflow Methods for Evaluating the Soil Hydraulic Functional Relationships Between NAPL Pressure and Saturation in Porous Media

2009 ◽  
pp. 105-105-14
Author(s):  
KM Bali ◽  
ME Grismer ◽  
JW Hopmans
Keyword(s):  
Porous Media ◽  
Functional Relationships ◽  
Soil Hydraulic

Pore-morphology-based simulations of drainage and wetting processes in porous media

2011 ◽  
Vol 42 (2-3) ◽  
pp. 128-149 ◽  
Author(s):  
T. P. Chan ◽  
Rao S. Govindaraju
Keyword(s):  
Porous Media ◽  
Hydraulic Properties ◽  
Pore Space ◽  
Water Pressure ◽  
Theoretical Models ◽  
Hysteretic Behavior ◽  
Water Retention Curve ◽  
Pore Morphology ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic

Soil hydraulic properties relating saturation, water pressure, and hydraulic conductivity are known to exhibit hysteresis. In this paper, we focus on the determination of the water retention curve for a porous medium through a novel pore-scale simulation technique that is based on mathematical morphology. We develop an algorithm that allows for the representation of three-dimensional randomly packed porous media of any geometry (i.e. not restricted to idealized geometries such as spherical or ellipsoidal particles/pore space) so that the connectivity-, tortuosity-, and hysteresis-causing mechanisms are represented in both drainage and wetting processes, and their role in determining macroscopic fluid behavior is made explicit. Using this method, we present simulation results that demonstrate hysteretic behavior of wetting and non-wetting phases during both drainage and wetting cycles. A new method for computing interfacial surface areas is developed. The pore-morphology-based method is critically evaluated for accuracy, sample size effects, and resolution effects. It is found that the method computes interfacial areas more accurately than existing methods and allows for (i) examination of relationships between water pressure, saturation and interfacial area for hysteretic soils, and (ii) comparisons with previously developed theoretical models of soil hydraulic properties. The pore-morphology-based method shows promise for applications in vadose zone hydrology.

scholarly journals Sensitivity analysis of unsaturated infiltration flow using head based finite element solution of Richards' equation

MATEMATIKA ◽  
2017 ◽  
Vol 33 (2) ◽  
pp. 131 ◽  
Author(s):  
Mohammad Sayful Islam
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Porous Media ◽  
Hydraulic Properties ◽  
Preferential Flow ◽  
Finite Element Solution ◽  
Richards Equation ◽  
Element Solution ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic

Sensitivity analysis is one of the tools available for analyzing the effects of soil parameter on the variably unsaturated flows in porous media, that may easily be implemented into existing conventional Galerkin finite element solution of Richards’ equation based computational fluid dynamics codes. The sensitivity of the model is evaluated on the basis vertical infiltration problem with time dependent boundary condition, sharp gradient in the infiltration front, and discontinuous derivatives in the soil hydraulic properties. Simulation results demonstrate the complicated nature of unsaturated porous media during redistribution water flow.  The sample case presented highlight different aspects of the performance of the algorithm and the different factors that can affect their convergence and efficiency, including temporal discretization, convergence error norm, conductivity and moisture content characteristics, boundary conditions, and the extent of fully unsaturated zones in the soil. From the preliminary assessment performed herein, consideration of the number of degrees of freedom used when performing a sensitivity analysis is shown to demand enormous concern, if predicted sensitivities are to have significant physical interpretations. The proposed model is capable of simulating preferential flow situations using parameters which can be related to soil hydraulic properties.

Sensitivity analysis of MOHID-Land model. Calibration and validation of Ulla river watershed.

2020 ◽  
Author(s):  
Ana Oliveira ◽  
Tiago B. Ramos ◽  
Lucian Simionesei ◽  
Lígia Pinto ◽  
Ramiro Neves
Keyword(s):  
Sensitivity Analysis ◽  
Porous Media ◽  
Channel Flow ◽  
Hydrological Model ◽  
Dew Point ◽  
Water Dynamics ◽  
River Watershed ◽  
Calibration And Validation ◽  
Soil Hydraulic ◽  
The Impact

<p>Nowadays flood warning systems are extremely important since they can provide critical information that can protect property and save lives. These systems should alert about whether a flood should be expected, when it will occur and how severe it will be.</p><p>A warning system can be based on the analysis of historical events and a good monitoring system or it can be based on the capacity of predict the channel flow in key locations. In the second case, these type of systems, known as forecast systems, consider the meteorological predictions as driving forces for a hydrological model which estimates the channel flow for the next few hours and days, considering the processes that take place in a watershed. A hydrological forecast can only be reliable when a good calibration and validation of watershed processes is performed.</p><p>This study aims to calibrate and validate the channel flow in Ulla river watershed (Galicia, Spain) using MOHID-Land model considering a sensitivity analysis of some parameters and user’s options that can affect model results. MOHID-Land model is a physically based, fully distributed model that considers four compartments or mediums: atmosphere, porous media, soil surface and river network. Water dynamics is computed through the different mediums using mass and momentum conservations equations.</p><p>The model was firstly implemented in the studied domain with a resolution of 500 m. Data inputs included the digital Global Digital Elevation Model from NASA with a resolution of 30 m; the Corine Land Cover map from 2012 with a resolution of 100m; the soil hydraulic properties from the multilayered European Soil Hydraulic Database with a resolution of 250 m; hourly meteorological data (precipitation, solar radiation, wind velocity, air temperature, surface pressure and dew point temperature) from ERA5-Reanalysis with a resolution of 31 km; and daily total outflow for three reservoirs present in this watershed.</p><p>The sensitivity analysis was performed to test the impact of grid and elevation data source resolution, cross-sections geometry, soil parameters, vertical soil discretization, surface and channel Manning coefficients, the infiltration process and deactivation of different modules such as porous media and vegetation on streamflow. The results of these tests were compared with a reference simulation by the analysis of flow duration curves.</p><p>The hydrological model was calibrated and validated in 4 hydrometric stations not influenced by reservoirs and the river flows considering the reservoirs operation were compared with measured values in 2 hydrometric stations. Four statistical parameters (R2, RMSE, PBIAS and NSE) were used to evaluate model performance at a daily scale which was considered good.</p>

Three-dimensional organization and functional relationships of endocytotic compartments in pig intestinal epithelial cells

1992 ◽  
Vol 50 (1) ◽  
pp. 576-577
Author(s):  
Julian P. Heath ◽  
Buford L. Nichols ◽  
László G. Kömüves
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Three Dimensional ◽  
Intestinal Epithelial ◽  
Cell Surfaces ◽  
Basal Surface ◽  
Functional Relationships

The newborn pig intestine is adapted for the rapid and efficient absorption of nutrients from colostrum. In enterocytes, colostral proteins are taken up into an apical endocytotic complex of channels that transports them to target organelles or to the basal surface for release into the circulation. The apical endocytotic complex of tubules and vesicles clearly is a major intersection in the routes taken by vesicles trafficking to and from the Golgi, lysosomes, and the apical and basolateral cell surfaces.Jejunal tissues were taken from piglets suckled for up to 6 hours and prepared for electron microscopy and immunocytochemistry as previously described.

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