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Showing 1 to 20 of 21 for “"Richards equation"”.
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Adjoint approach to parameter identification with application to the Richards equation
… of quasilinear parabolic partial differential equations is considered. An approach based on utilizing adjoint versions of the direct problems to derive integral equations explicitly relating changes in inputs (coefficients) to changes in outputs (measured data) is presented. Using the integral …
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X-ray attenuation techniques to explore the dynamics of water in porous media
… in an unsaturated porous medium is described by Richards' equation. It is based on the assumption that the air in the pores is arbitrarily mobile and able to disappear from the pore space at any time. To solve Richards' equation a parameterization of the relationship between the water content and …
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Infiltration Models for Engineered Media in Living Roofs and Bioretention
… and (2) the application of the classic Richards equation with commonly-used hydraulic functions for modeling one-dimensional infiltration process in unsaturated engineered media. The hydraulic properties, including saturated hydraulic conductivity (Ks), water retention characteristic …
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Modeling transport of agricultural chemicals in a dual porosity system resulting from macropores
… Flow of water in both regions is governed by Richards' equation and chemical transport is based upon convective-dispersive mechanisms with linear kinetic sorption and first-order decay. The pressure-water content and the pressure-conductivity relationship for the unsaturated soil in each of …
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Approximate analytical solutions for modeling subsurface flow
Equations of subsurface flow of water, the Richards equation and the Boussinesq equation, have no known exact analytical solutions. Approximate analytical solutions to these equations have been developed under linearizing simplifications. In the first part of the dissertation two commonly used …
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Development of unsaturated flow functions for low impact development stormwater management systems filter media and flow routines for hydrological modeling of permeable pavement systems
… this dissertation, the appropriate equations for representing different flow components of LID systems are investigated. Special attention was given to modeling water routing through the filter media layers of LID systems. The water movement through a permeable pavement system was …
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Zur gekoppelten numerischen Modellierung von unterirdischem Hochwasser
… be mathematically described by the Navier-Stokes equations or simplifications of these equations. As a programme to model the movement of water on an inundated area, Ilmoflood is presented. For the subsurface, the Richards equation and the groundwater flow equation are appropriate. The Feflow …
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Simulação do fenômeno de infiltração em modelos chuva-vazão
… porous media, an extension of Green & Ampt's equation (Morel-Seytoux e Khanji,1974; Morel-Seytoux, 1978) was been used to estimate infiltrated water and excess rainfall volumes. Simulated values showed good agreement when compared with Richards' equation numerical solution. Green & Ampt's …
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Coupled transport in natural porous media
… systems, a set of partial differential equations and appropriate parameter functions for the study of coupled water, heat, gas and solute transport was formulated and a state of the art computer model for the numerical solution of the equation system was created. A new phase …
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Modeling and measurement of tile drain controls in intensively managed landscapes
… obtained by modifications of variably saturated Richards equation to capture the impacts of tile drain on soil moisture. The coupling between subsurface and overland flow is obtained by prescribing a boundary condition switching approach at the top surface of the computational domain. Model …
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Three-Dimensional Volume Averaged Soil-Moisture Transport Model: A Scalable Scheme for Representing Subgrid Topographic Control in Land-Atmosphere Interactions
… Transport (VAST) formulation is derived from the Richards equation to incorporate the lateral flow and subgrid heterogeneity due to topography. A conjunctive surface-subsurface flow model at a large scale, a 1-D Diffusion Wave (DW) surface flow model interacting with the 3-D VAST model, is …
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Effective Green and Ampt parameters for two layered soils
… with MIKE SHE simulation results based on Richards equation for different layer thicknesses, soil properties, and rainfall hyetographs. These results show that the proposed simple and quick procedures for estimating effective soil parameters show good agreement in terms of the volume of …
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A Model for Simulating Soil-Zone Processes at the Regional Scale
… percolation. In a series of test simulations, Richards' equation (RE) was compared with MODFLOW-SZF. Across a range of hydraulic conductivities and applied precipitation rates, MODFLOW-SZF achieved a good infiltration and interflow solution (0.014-0.052 RMSE) with only 6 grid cells and 0.11 …
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Effects of fractional time derivatives in predator-prey models
… analytical solution for the characteristic equation of the incommensurate system when the two fractional orders α and β are similar and both close to the critical value of the fractional order of the commensurate system.;In this case, we are able to map out the stable and unstable boundary …
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Multiphysics Simulation and Innovative Characterization of Freezing Soils
… the knowledge base. The new model couples heat equation for heat transfer, modified Richards’ equation for fluid transfer, and mechanical constitutive relationships. Auxiliary relationships, such as the similarity between drying and freezing processes and the Clapeyron equation for phase …
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Mechanics of biocell landfill settlements
… used to link settlement with gas pressure. The Richards equation was used to simulate the distribution of moisture. A computer program was written to numerically predict the settlements, gas pressure and volumetric moisture content in a biocell landfill using landfill geometry and waste …
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THE CHARACTERIZATION AND MODELLING/OF SOIL WATER PATHWAYS BENEATH A CONIFEROUS HILLSLOPE IN MID WALES
… all of the properties contained within the Darcy-Richards equation. The marked horizon development within the ferric podzol soil of the instrumented forest hillslope, in particular the presence of an indurated B horizon, deflects most percolation laterally within the 0/A and A/E horizons. This …
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Quantification of wildfire-induced perturbations to soil-water retention curves and their impact on rainfall runoff
… is commonly described using the Van Genuchten equation, in which key parameters are the residual water content, θr, saturated water content, θs, the pore-size distribution index, n, and the inverse of the air-entry pressure head, α. To date, the degree to which SWRCs are perturbed by wildfire …
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Preferential movement of solutes through soils
… Flow and solute transport are described by the Richards' equation and the convection-dispersion equation. Flow in the macropores is described by the Hagen-Poiseuille equation. An axisymmetric coordinate system is used to simulate the flow and solute transport from the macropore into the …
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Modelling steroidal hormone transport and evaluating best management practices in New Zealand dairy farming systems
… zone model implemented in MATLAB, coupling Richards’ equation with a Green-Ampt infiltration framework and advection, dispersion, and sorption processes to track estrogen movement through soil. The second approach employed a GIS-based ArcSWAT catchment model to simulate surface runoff, …
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